The thesis starts by showing that at the earliest stage of vision, biological systems implement a mechanism that is computationally equivalent to computing local geometric invariants at the two-dimensional curve level. The availability of this information establishes the foundation for computing components of a differential geometry language from sensory inputs. The mathematical framework of scale space that makes this computational approach possible, likewise, has its biological basis.

On the other hand, visual perception is a global phenomenon that occurs generally in a 3D space. To understand this process and design computational systems that have comparable performance to humans requires specification of how a 2D local computational mechanism can be used in this global 3D environment. This goal is achieved through two steps. First, a global surface representation formulation is extended from the 2D framework. It is shown how local geometric features that are sparse and perceptually meaningful can be naturally used to represent global 3D surfaces. Second, active motion by an observer is introduced as an additional dimension to the data set so that the observer becomes mobile and can react to observations or verify hypotheses actively. This also makes dynamical data such as optical flow available to the observer. These added abilities enable the observer to perform tasks such as surface recovery and 3D navigation. In addition, the modeling process of 3D objects is naturally constrained by the computational resources available to the observer so that the model is inherently incremental.

This thesis contributes in the following areas: (1) direct computation
of 2D differential geometric invariants from images using methods
comparable to the human vision system, (2) perception-based global
representations of 2D and 3D objects using geometric invariants,
(3) novel methods for optical flow computation and segmentation,
and (4) active methods for global surface recovery and navigation
using both stationary contours, apparent contours and textured surfaces.
}
BIBTEX
{
@phdthesis{ Yu:1999:phd,
author = "L-Y. Yu",
title = "Active 3D Surface Modeling using Perception-Based, Differential Geometric Primitives",
school = "University of Wisconsin",
address = "Madison, WI",
year = 1999}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1998 }
--------------------------------------------------------------
KEY { dyer.1998.iuw }
TITLE { Image-Based Visualization from Widely-Separated Views }
AUTHORS { C. R. Dyer }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1998, 101-105. }
ABSTRACT
{
This report describes image-based
visualization research in support of video surveillance
and monitoring systems.
Our primary goal is to develop
methods so a user can interactively visualize
a 3D environment from images captured
by a set of widely-separated cameras.
Results include view interpolation of dynamic scenes,
coarse-to-fine voxel coloring for efficient scene reconstruction,
and recovering scene structure and camera motion.
}
BIBTEX
{
@inproceedings{ Dyer:1998:iuw,
author = "Charles R. Dyer",
title = "Image-Based Visualization from Widely-Separated Views",
booktitle = "Proc. Image Understanding Workshop",
pages = "101--105",
year = 1998}
}
--------------------------------------------------------------
KEY { prock.1998.iuw }
TITLE { Towards Real-Time Voxel Coloring }
AUTHORS { A. C. Prock and C. R. Dyer }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1998, 315-321. }
ABSTRACT
{
Techniques for constructing three-dimensional scene models from
two-dimensional images are often slow and unsuitable for
interactive, real-time applications. In this paper we explore
three methods of enhancing the performance of the voxel coloring
reconstruction method. The first approach uses texture mapping
to leverage hardware acceleration. The second approach uses
spatial coherence and a coarse-to-fine strategy to focus
computation on the filled parts of scene space. Finally, the
multi-resolution method is extended over time to enhance
performance for dynamic scenes.
}
BIBTEX
{
@inproceedings{ Prock:1998:iuw,
author = "Andrew C. Prock and Charles R. Dyer",
title = "Towards Real-Time Voxel Coloring",
booktitle = "Proc. Image Understanding Workshop",
year = 1998,
pages = {315--321} }
}
--------------------------------------------------------------
KEY { manning.1998.iuw }
TITLE { Interpolating View and Scene Motion by Dynamic View Morphing }
AUTHORS { R. A. Manning and C. R. Dyer }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1998, 323-330 }
ABSTRACT
{
We present a novel technique for interpolating between two views of a
dynamic scene. Our approach extends the concept of view morphing
introduced in [Seitz and Dyer, 1996] and retains the relative
advantages of that method. The interpolation will portray one possible
physicallyvalid version of what transpired in the scene during the
intervening time between views. The scene is assumed to consist of a
small number of objects. Each object can undergo any motion during the
time between views as long as the total movement is equivalent to a
single, rigid translation. The dynamic view morphing technique can
work with widely-spaced reference views, sparse point correspondences,
and uncalibrated cameras. When the camerato-camera transformation can
be determined, the virtual objects can be portrayed moving along
straight-line, constant-velocity trajectories. Methods are developed
for determining the camera-to-camera transformation from information
available in the reference views. It is shown that each moving object
in a scene has a corresponding fundamental matrix and that the
camera-to-camera transformation can be determined from two distinct
fundamental matrices. Dynamic view morphing is developed for both
pinhole and orthographic cameras, and the use of three or more
reference views is discussed. Static view morphing is made more
versatile with respect to occlusion, and mosaicing is combined with
dynamic view morphing for the case when both reference views share the
same optical center. The resulting combination of techniques can be
used to fill-in missing gaps in movies, perform "view hand-offs"
between cameras at different locations, create movies from still
images, perform movie stabilization and compression, track objects
during periods of obstruction, and related tasks.
}
BIBTEX
{
@inproceedings{ Manning:1998:iuw,
author = "Russell A. Manning and Charles R. Dyer",
title = "Interpolating View and Scene Motion by Dynamic View Morphing",
booktitle = IUW,
year = 1998,
pages = {323--330} }
}
--------------------------------------------------------------
KEY { manning.1998.tr1387 }
TITLE { Dynamic View Morphing }
AUTHORS { R. A. Manning and C. R. Dyer }
PUBLISHEDIN
{
Computer Sciences Department Technical Report 1387,
University of Wisconsin - Madison, September 1998.
}
ABSTRACT
{
We present a novel technique for interpolating between two views of a
dynamic scene. Our approach extends the concept of view morphing and
retains the relative advantages of that method. The interpolation
will portray *one possible* physically-valid version of what
transpired in the scene during the intervening time between views.
The scene is assumed to consist of a small number of *objects*.
Each object can undergo any motion during the time between views as
long as its total movement is equivalent to a single, rigid
translation. The dynamic view morphing technique can work with
widely-spaced reference views, sparse point correspondences, and
uncalibrated cameras. When the *camera-to-camera transformation*
can be determined, the virtual objects can be portrayed moving along
straight-line, constant-velocity trajectories. Methods are developed
for determining the camera-to-camera transformation from information
available in the reference views. It is shown that each moving object
in a scene has a corresponding fundamental matrix and that the
camera-to-camera transformation can be determined from two distinct
fundamental matrices. Dynamic view morphing is developed for both
pinhole and orthographic cameras, and the use of three or more
reference views is discussed. Static view morphing is made more
versatile with respect to occlusion, and mosaicing is combined with
dynamic view morphing for the case when both reference views share the
same optical center. The resulting combination of techniques can be
used to fill-in missing gaps in movies, perform ``view hand-offs"
between cameras at different locations, create movies from still
images, perform movie stabilization and compression, track objects
during periods of obstruction, and related tasks.
}
NOTES
{
*Very long, thorough coverage of the topic. Contains much information not found in the
CVPR99 paper.*
}
BIBTEX
{
@techreport{ Manning:1998:tr,
author = "Russell A. Manning and Charles R. Dyer",
title = "Dynamic View Morphing",
institution = "Computer Sciences Department, University of Wisconsin-Madison",
number = 1387,
year = 1998 }
}
--------------------------------------------------------------
KEY { seitz.1998.iccv }
TITLE { Plenoptic Image Editing }
AUTHORS { S. M. Seitz and K. N. Kutulakos }
PUBLISHEDIN { Proc. 6th Int. Conf. Computer Vision, 1998, 17-24 }
ABSTRACT
{
This paper presents a new class of interactive image editing operations
designed to maintain physical consistency between multiple images of a
physical 3D object. The distinguishing feature of these operations is that
edits to any one image propagate automatically to all other images as if the
(unknown) 3D object had itself been modified. The approach is useful first
as a power-assist that enables a user to quickly modify many images by
editing just a few, and second as a means for constructing and editing
image-based scene representations by manipulating a set of photographs.
The approach works by extending operations like image painting,
scissoring, and morphing so that they alter an object's plenoptic function in
a physically-consistent way, thereby affecting object appearance from all
viewpoints simultaneously. A key element in realizing these operations is a
new volumetric decomposition technique for reconstructing an object's
plenoptic function from an incomplete set of camera viewpoints.
}
BIBTEX
{
@inproceedings{ Seitz:1998:iccv,
author = "Steven M. Seitz and Kyros N. Kutulakos",
title = "Plenoptic Image Editing",
booktitle = "Proc. 6th Int. Conf. Computer Vision",
pages = "17--24",
year = 1998 }
}
--------------------------------------------------------------
KEY { bestor.1998.thesis }
TITLE { Recovering Feature and Observer Position by Projected Error Refinement }
AUTHORS { G. S. Bestor }
PUBLISHEDIN
{
Ph.D. Dissertation, Computer Sciences Department Technical Report 1381,
University of Wisconsin - Madison, August 1998.
}
ABSTRACT
{
Recovering three-dimensional information from images is a principal goal of
computer vision. An approach called Structure From Motion (SFM) does so
without imposing strict requirements on the observer or scene. In
particular, SFM assumes camera motion is unknown and the scene is only
required to be static. This thesis describes a new SFM technique called
Projected Error Refinement that computes the positions of feature points
(i.e., structure) and the locations of the camera or observer (i.e., motion)
from a noisy image sequence. The technique addresses limitations of
existing SFM techniques that make them unsuitable except in controlled
environments; the approach presented in this thesis models perspective
projection, allows unconstrained camera motion, deals with outliers and
occlusion, and is scalable. This new technique is recursive and thus is
suitable for video image streams because new images can be added at any
time.

Projected Error Refinement views SFM as a geometric inverse projection problem, with the goal of determining the positions of the cameras and feature points such that the projectors defined by each image optimally intersect (projectors are the lines of projection specifying the direction of each feature point from the camera's optical center). This is expressed as a global optimization problem with the objective function minimizing the mean-squared angular projection error between the solution and the observed images. Occlusion is dealt with naturally in this approach because only visible feature points define projectors that are considered during optimization - occluded features are ignored. The technique models true perspective projection and is scalable to an arbitrary number of feature points and images. Projected Error Refinement is non-linear and uses an efficient parallel iterative refinement algorithm that takes an initial estimate of the structure and motion parameters and alternately refines the cameras' poses and the positions of the feature points in parallel. The solution can be refined to an arbitrary precision or refinement can be terminated prematurely due to limited processing time. The solution converges rapidly towards the global minimum even when started from a poor initial estimate. Experimental results are given for both 2D and 3D perspective projection using real and synthetic images sequences. } BIBTEX { @phdthesis{ Bestor:1998:phd, author = "Gareth Bestor", title = "Recovering Feature and Observer Position by Projected Error Refinement", school = "University of Wisconsin", address = "Madison, WI", year = 1998} } -------------------------------------------------------------- KEY { yu.1998.icip } TITLE { Direct Computation of Differential Invariants of Image Contours from Shading } AUTHORS { L-Y. Yu and C. R. Dyer } PUBLISHEDIN { Proc. 5th Int. Conf. Image Processing, 1998. } ABSTRACT { In this paper we present a framework combining differential geometry and scale-space to show that local geometric invariants of image contours such as tangent, curvatureand derivative of curvature can be computed directly and stably from the raw image itself.

To solve the problem of noise amplification by differential operations, scale-parameterized local kernels are used to replace differential operations by integral operations,which can be carried out accurately when we adopt a continuous image model. We also show that tangent estimationalong contours can be made quite accurately using only eight tangent estimators (a \pi/4 quantization) when contour location is known, and high precision and efficiency in computation can be achieved for each of the invariantsregardless of the differential order involved. } BIBTEX { @inproceedings{ Yu:1998:icip, author = "L-Y. Yu and Charles R. Dyer", title = "Direct Computation of Differential Invariants of Image Contours from Shading", booktitle = "Proc. 5th Int. Conf. Image Processing", year = 1998} } -------------------------------------------------------------- ############################################################## ############################################################## ############################################################## YEAR { 1997 } -------------------------------------------------------------- KEY { seitz.1997.rochester } TITLE { Plenoptic Image Editing } AUTHORS { S. M. Seitz and K. N. Kutulakos } PUBLISHEDIN { Computer Science Department Technical Report 647, University of Rochester, Rochester, NY, January 1997. } ABSTRACT { This paper presents a new class of interactive image editing operations designed to maintain consistency between multiple images of a physical 3D object. The distinguishing feature of these operations is that edits to any one image propagate automatically to all other images as if the (unknown) 3D object had itself been modified. The approach is useful first as a power-assist that enables a user to quickly modify many images by editing just a few, and second as a means for constructing and editing image-based scene representations by manipulating a set of photographs. The approach works by extending operations like image painting, scissoring, and morphing so that they alter an object's plenoptic function in a physically-consistent way, thereby affecting object appearance from all viewpoints simultaneously. A key element in realizing these operations is a new volumetric decomposition technique for reconstructing an object's plenoptic function from an incomplete setof camera viewpoints. } ##LOCATION { ftp://ftp.cs.rochester.edu/pub/papers/robotics/97.tr647.Plenoptic_image_editing.ps.gz } BIBTEX { @techreport{ Seitz:1997:rochester, author = "S. M. Seitz and K. N. Kutulakos", title = "Plenoptic Image Editing", institution = "Computer Sciences Department, University of Rochester", number = "647", month = "January", year = 1997} } -------------------------------------------------------------- KEY { seitz.1997.thesis } TITLE { Image-Based Transformation of Viewpoint and Scene Appearance } AUTHORS { S. M. Seitz } PUBLISHEDIN { Ph.D. Dissertation, Computer Sciences Department Technical Report 1354, University of Wisconsin - Madison, October 1997. } ABSTRACT { This thesis addresses the problem of synthesizing images of real scenes under three-dimensional transformations in viewpoint and appearance. Solving this problem enables interactive viewing of remote scenes on a computer, in which a user can move a virtual camera through the environment and virtually paint or sculpt objects in the scene. It is demonstrated that a variety of three-dimensional scene transformations can be rendered on a video display device by applying simple transformations to a set of basis images of the scene. The virtue of these transformations is that they operate directly on images and recover only the scene information that is required in order to accomplish the desired effect. Consequently, they are applicable in situations where accurate three-dimensional models are difficult or impossible to obtain.

A central topic is the problem of *view synthesis*, i.e.,
rendering images of a real scene from different camera viewpoints by
processing a set of basis images. Towards this end, two algorithms
are described that warp and resample pixels in a set of basis images
to produce new images that are physically-valid, i.e., they correspond
to what a real camera would see from the specified viewpoints.
Techniques for synthesizing other types of transformations, e.g.,
non-rigid shape and color transformations, are also discussed. The
techniques are found to perform well on a wide variety of real and
synthetic images.

A basic question is uniqueness, i.e., for which views is the
appearance of the scene uniquely determined from the information
present in the basis views. An important contribution is a uniqueness
result for the no-occlusion case, which proves that all views on the
line segment between the two camera centers are uniquely determined
from two uncalibrated views of a scene. Importantly, neither dense
pixel correspondence nor camera information is needed. From this
result, a *view morphing* algorithm is derived that produces
high quality viewpoint and shape transformations from two uncalibrated
images.

To treat the general case of many views, a novel *voxel coloring*
framework is introduced that facilitates the analysis of ambiguities in
correspondence and scene reconstruction. Using this framework, a new type
of scene invariant, called *color invariant*, is derived, which provides
intrinsic scene information useful for correspondence and view synthesis.
Based on this result, an efficient voxel-based algorithm is introduced to
compute reconstructions and dense correspondence from a set of basis views.
This algorithm has several advantages, most notably its ability to easily
handle occlusion and views that are arbitrarily far apart, and its
usefulness for *panoramic* visualization of scenes. These factors
also make the voxel coloring approach attractive as a means for obtaining
high-quality three-dimensional reconstructions from photographs.
}
BIBTEX
{
@phdthesis{ Seitz:1997:phd,
author = "Steven M. Seitz",
title = "Image-Based Transformation of Viewpoint and Scene Appearance",
school = "University of Wisconsin",
address = "Madison, WI",
year = 1997}
}
--------------------------------------------------------------
KEY { seitz.1997.cvpr }
TITLE { Photorealistic Scene Reconstruction by Voxel Coloring }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1997, 1067-1073. }
ABSTRACT
{
A novel scene reconstruction technique is presented, different from
previous approaches in its ability to copewith large changes in
visibility and its modeling of intrinsic scene color and texture
information. The method avoids image correspondence problems by
working in adiscretized scene space whose voxels are traversed in a
fixed visibility ordering. This strategy takes full account of
occlusions and allows the input cameras to be far apartand widely
distributed about the environment. The algorithm identifies a special
set of invariant voxels which together form a spatial and photometric
reconstruction of the scene, fully consistent with the input
images. The approach is evaluated with images from both inward- and
outward-facing cameras.
}
BIBTEX
{
@inproceedings{seitz:cvpr97,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Photorealistic Scene Reconstruction by Voxel Coloring",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
pages = {1067-1073},
year = 1997}
}
--------------------------------------------------------------
KEY { seitz.1997.iuw.b }
TITLE { Photorealistic Scene Reconstruction by Voxel Coloring }
AUTHORS { S. M. Seitz }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1997, 935-942. }
ABSTRACT
{
A novel scene reconstruction technique is presented, different from
previous approaches in its ability to cope with large changes in
visibility and its modeling of intrinsic scene color and texture
information. The method avoids image correspondence problems by
working in a discretized scene space whose voxels are traversed in a
fixed visibility ordering. This strategy takes full account of
occlusions and allows the input cameras to be far apart and widely
distributed about the environment. The algorithm identifies a special
set of invariant voxels which together form a spatial and photometric
reconstruction of the scene, fully consistent with the input images.
}
BIBTEX
{
@inproceedings{seitz:iuw97b,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Photorealistic Scene Reconstruction by Voxel Coloring",
booktitle = "Proc. Image Understanding Workshop",
year = 1997,
pages = {935-942} }
}
--------------------------------------------------------------
KEY { dyer.1997.iuw }
TITLE { Image-Based Scene Rendering and Manipulation Research at the University of Wisconsin }
AUTHORS { C. R. Dyer }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1997, 63-67. }
ABSTRACT
{
This report summarizes the research effort at the University of
Wisconsin in support of the VSAM Program. Our primary goal is to
develop technologies so a user can interactively visualize and
virtually modify a 3D environment from a set of images. Current
approaches are described for image-based scene rendering, scene
manipulation, and appearance modeling.
}
BIBTEX
{
@inproceedings{ Dyer:1997:iuw,
author = "Charles R. Dyer",
title = "Image-Based Scene Rendering and Manipulation Research at the University of Wisconsin",
booktitle = "Proc. Image Understanding Workshop",
pages = "63--67",
year = 1997}
}
--------------------------------------------------------------
KEY { seitz.1997.imagina }
TITLE { Bringing Photographs to Life with View Morphing }
AUTHORS { S. M. Seitz }
PUBLISHEDIN { Proc. Imagina 97, 1997, 153-158. }
ABSTRACT
{
Photographs and paintings are limited in the amount of information they
can convey due to their inherent lack of motion and depth. Using image
morphing methods, it is now possible to add 2D motion to photographs
by moving and blending image pixels in creative ways. We have taken this
concept a step further by adding the ability to convey three-dimensional
motions, such as scene rotations and viewpoint changes, by manipulating one
or more photographs of a scene. The effect transforms a photograph or
painting into an interactive visualization of the underlying object or scene
in which the world may be rotated in 3D. Several potential
applications of this technology are discussed, in areas such
as virtual reality, image databases, and special effects.
}
BIBTEX
{
@inproceedings{seitz:ima97,
author = "Steven M. Seitz",
title = "Bringing Photographs to Life with View Morphing",
booktitle = "Proc. Imagina 97 Conf.",
address = "Monaco",
year = 1997,
pages = {153-158} }
}
--------------------------------------------------------------
KEY { seitz.1997.iuw.a }
TITLE { View Morphing: Uniquely Predicting Scene Appearance from Basis Images }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. Image Understanding Workshop, 1997, 881-887. }
ABSTRACT
{
This paper analyzes the conditions when a discrete set of images
implicitly describes scene appearance for a continuous range of
viewpoints. It is shown that two basis views of a static scene
uniquely determine the set of all views on the line between their
optical centers when a visibility constraint is satisfied. Additional
basis views extend the range of predictable views to 2D or 3D regions
of viewpoints. A simple scanline algorithm called *view
morphing* is presented for generating these views from a set of
basis images. The technique is applicable to both calibrated and
uncalibrated images.
}
BIBTEX
{
@inproceedings{ Seitz:1997:iuw,
author = "Steven M. Seitz and Charles R. Dyer",
title = "View {M}orphing: Uniquely Predicting Scene Appearance from Basis Images",
booktitle = IUW,
pages = {881--887},
year = 1997}
}
--------------------------------------------------------------
KEY { seitz.1997.ijcv }
TITLE { View-Invariant Analysis of Cyclic Motion }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Int. J. Computer Vision, **25(3)**, 1997, 231-251. }
ABSTRACT
{
This paper presents a general framework for image-based analysis of 3D
repeatingmotions that addresses two limitations in the state of the art.
First, the assumption that a motion be perfectly even from one cycle to
the next is relaxed. Real repeating motions tend not to be perfectly even,
i.e., the length of a cycle varies through time because of physically important
changes in the scene. A generalization of {\em period} is defined for
repeating motions that makes this temporal variation explicit. This
representation, called the period trace, is compact and purely temporal,
describing the evolution of an object or scene without reference to spatial
quantities such as position or velocity. Second, the requirement that the
observer be stationary is removed. Observer motion complicates image analysis
because an object that undergoes a 3D repeating motion will generally not
produce a repeating sequence of images. Using principles of affine
invariance, we derive necessary and sufficient conditions for an image
sequence to be the projection of a 3D repeating motion, accounting for
changes in viewpoint and other camera parameters.
Unlike previous work in visual invariance, however, our approach is
applicable to objects and scenes whose motion is highly non-rigid.
Experiments on real image sequences demonstrate how the approach may be
used to detect several types of purely temporal motion features, relating to
motion trends and irregularities.
Applications to athletic and medical motion analysis are discussed.
}
BIBTEX
{
@article{seitz:ijcv97,
author = "Steven M. Seitz and Charles R. Dyer",
title = "View-Invariant Analysis of Cyclic Motion",
journal = "Int. J. of Computer Vision",
volume = 25,
number = 3,
year = 1997,
pages = {231--251} }
}
--------------------------------------------------------------
KEY { seitz.1997.mbr }
TITLE { Cyclic Motion Analysis using the Period Trace }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Motion-Based Recognition, M. Shah and R. Jain, eds., Kluwer, Boston, 1997, 61-85. }
ABSTRACT
{
A new technique is presented for computing 3D scene structure from point
and line features in monocular image sequences. Unlike previous methods,
the technique guarantees the completeness of the recovered scene, ensuring
that every scene feature that is detected in each image is reconstructed.
The approach relies on the presence of four or more reference features
whose correspondences are known in all the images. Under an orthographic
or affine camera model, the parallax of the reference features provides
constraints that simplify the recovery of the rest of the visible scene.
An efficient recursive algorithm is described that uses a unified framework
for point and line features. The algorithm integrates the tasks of feature
correspondence and structure recovery, ensuring that all reconstructible
features are tracked. In addition, the algorithm is immune to outliers and
feature-drift, two weaknesses of existing structure-from-motion techniques.
Experimental results are presented for real images.
}
BIBTEX
{
@incollection{seitz:mbr97,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Cyclic Motion Analysis Using the Period Trace",
booktitle = "Motion-Based Recognition (M. Shah and R. Jain, Eds.)",
publisher = "Kluwer Academic Publishers",
address = "Boston, MA",
pages = {61-85},
year = 1997}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1996 }
--------------------------------------------------------------
KEY { seitz.1996.sigg }
TITLE { View Morphing }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. SIGGRAPH 96, 1996, 21-30. }
ABSTRACT
{
Image morphing techniques can generate compelling 2D transitions
between images. However, differences in object pose or viewpoint
often cause unnatural distortions in image morphs that are difficult
to correct manually. Using basic principles of projective geometry,
this paper introduces a simple extension to image morphing that
correctly handles 3D projective camera and scene transformations. The
technique, called * view morphing*, works by prewarping two
images prior to computing a morph and then postwarping the
interpolated images. Because no knowledge of 3D shape is required,
the technique may be applied to photographs and drawings, as well as
rendered scenes. The ability to synthesize changes both in viewpoint
and image structure affords a wide variety of interesting 3D effects
via simple image transformations.
}
BIBTEX
{
@inproceedings{ Seitz:1996:siggraph,
author = "Steven M. Seitz and Charles R. Dyer",
title = "View Morphing",
booktitle = SIGGRAPH96,
pages = {21--30},
year = 1996}
}
--------------------------------------------------------------
KEY { seitz.1996.icpr }
TITLE { Toward Image-Based Scene Representation Using View Morphing }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. 13th Int. Conf. Pattern Recognition, Vol. I, Track A: Computer Vision, 1996, 84-89. }
ABSTRACT
{
The question of which views may be inferred from a set of basis images
is addressed. Under certain conditions, a discrete set of images
implicitly describes scene appearance for a continuous range of viewpoints.
In particular, it is demonstrated that two basis views of a static scene
determine the set of all views on the line between their optical centers.
Additional basis views further extend the range of predictable views to a
two- or three-dimensional region of viewspace. These results are shown to
apply under perspective projection subject to a generic visibility
constraint called monotonicity. In addition, a simple scanline algorithm is
presented for actually generating these views from a set of basis images.
The technique, called * view morphing* may be applied to both calibrated
and uncalibrated images. At a minimum, two basis views and their
fundamental matrix are needed. Experimental results are presented on
real images. This work provides a theoretical foundation for image-based
representations of 3D scenes by demonstrating that perspective view
synthesis is a theoretically well-posed problem.
}
BIBTEX
{
@inproceedings{ Seitz:1996:icpr,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Toward Image-Based Scene Representation Using View Morphing",
booktitle = "Proc. 13th Int. Conf. on Pattern Recognition, Vol. I",
pages = {84--89},
year = 1996}
}
--------------------------------------------------------------
KEY { yu.1996.fest }
TITLE { Shape Recovery from Stationary Surface Contours by Controlled Observer Motion }
AUTHORS { L. Yu and C. R. Dyer }
PUBLISHEDIN { Advances in Image Understanding: A Festschrift for Azriel Rosenfeld, IEEE Computer Society Press, Los Alamitos, Ca., 1996, 177-193. }
ABSTRACT
{
The projected deformation of stationary contours and markings on
object surfaces is analyzed in this paper. It is shown that given a
marked point on a stationary contour, an active observer can move
deterministically to the osculating plane for that point by observing
and controlling the deformation of the projected contour. Reaching the
osculating plane enables the observer to recover the object surface
shape along the contour as well as the Frenet frame of the
contour. Complete local surface recovery requires either two
intersecting surface contours and the knowledge of one principle
direction, or more than two intersecting contours. To reach the
osculating plane, two strategies involving both pure translation and a
combination of translation and rotation are analyzed. Once the Frenet
frame for the marked point on the contour is recovered, the same
information for all points on the contour can be recovered by staying
on osculating planes while moving along the contour. It is also shown
that occluding contours and stationary contours deform in a
qualitatively different way and the problem of discriminating between
these two types of contours can be resolved before the recovery of
local surface shape.
}
BIBTEX
{
@inbook{ Yu:1996:chapter,
author = "Liangyin Yu and Charles R. Dyer",
title = "Shape Recovery from Stationary Surface Contours by Controlled Observer Motion",
booktitle = "Advances in Image Understanding: A Festschrift for Azriel Rosenfeld (K. Bowyer and N. Ahuja, Eds.)",
publisher = "IEEE Computer Society Press",
pages = {177--193},
year = 1996}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1995 }
--------------------------------------------------------------
KEY { seitz.1995.rvs }
TITLE { Physically-Valid View Synthesis by Image Interpolation }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. Workshop on Representation of Visual Scenes, 1995, 18-25. }
ABSTRACT
{
Image warping is a popular tool for smoothly transforming one image to
another. ``Morphing'' techniques based on geometric image
interpolation create compelling visual effects, but the validity of
such transformations has not been established. In particular, does 2D
interpolation of two views of the same scene produce a sequence of
physically valid in-between views of that scene? In this paper, we
describe a simple image rectification procedure which guarantees that
interpolation does in fact produce valid views, under generic
assumptions about visibility and the projection process. Towards this
end, it is first shown that two basis views are sufficient to predict
the appearance of the scene within a specific range of new viewpoints.
Second, it is demonstrated that interpolation of the rectified basis
images produces exactly this range of views. Finally, it is shown
that generating this range of views is a theoretically well-posed
problem, requiring neither knowledge of camera positions nor 3D scene
reconstruction. A scanline algorithm for view interpolation is
presented that requires only four user-provided feature
correspondences to produce valid orthographic views. The quality of
the resulting images is demonstrated with interpolations of real
imagery.
}
BIBTEX
{
@inproceedings{ Seitz:1995:wrvs,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Physically-Valid View Synthesis by Image Interpolation",
booktitle = "Proc. IEEE Workshop on Representations of Visual Scenes",
pages = {18--25},
year = 1995}
}
--------------------------------------------------------------
KEY { seitz.1995.iccv }
TITLE { Complete Scene Structure from Four Point Correspondences }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. 5th Int. Conf. Computer Vision, 1995, 330-337. }
ABSTRACT
{
A new technique is presented for computing 3D scene structure from
point and line features in monocular image sequences. Unlike previous
methods, the technique guarantees the completeness of the recovered
scene, ensuring that every scene feature that is detected in each
image is reconstructed. The approach relies on the presence of four or
more reference features whose correspondences are known in all the
images. Under an orthographic or affine camera model, the parallax of
the reference features provides constraints that simplify the recovery
of the rest of the visible scene. An efficient recursive algorithm is
described that uses a unified framework for point and line
features. The algorithm integrates the tasks of feature correspondence
and structure recovery, ensuring that all reconstructible features are
tracked. In addition, the algorithm is immune to outliers and
feature-drift, two weaknesses of existing structure-from-motion
techniques. Experimental results are presented for real images.
}
BIBTEX
{
@inproceedings{seitz:iccv95,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Complete Scene Structure from Four Point Correspondences",
booktitle = "Proc. Fifth Int. Conf. on Computer Vision",
pages = {330-337},
year = 1995}
}
--------------------------------------------------------------
KEY { lai.1995.pami }
TITLE { Deformable Contours: Modeling and Extraction }
AUTHORS { K. F. Lai and R. T. Chin }
PUBLISHEDIN { IEEE Trans. Pattern Analysis and Machine Intell. **17**, 1995, 1084-1090. }
ABSTRACT
{
This paper considers the problem of modeling and extracting arbitrary deformable
contours from noisy images. We propose a global contour model based on a stable
and regenerative shape matrix, which is invariant and unique under rigid
motions. Combined with Markov random field to model local deformations, this
yields prior distribution that exerts influence over a global model while
allowing for deformations. We then cast the problem of extraction into posterior
estimation and show its equivalence to energy minimization of a generalized
active contour model. We discuss pertinent issues in shape training, energy
minimization, line search strategies, minimax regularization and initialization
by generalized Hough transform. Finally, we present experimental results and
compare its performance to rigid template matching.
}
BIBTEX
{
@article{ Lai:1995:pami,
author = "K. F. Lai and R. T. Chin",
title = "Deformable Contours: Modeling and Extraction",
journal = "IEEE Trans. Pattern Analysis and Machine Intelligence",
volume = "17",
year = "1995",
pages = "1084--1090"}
}
--------------------------------------------------------------
KEY { hibbard.1995.thesis }
TITLE { Visualizing Scientific Computations: A System based on Lattice-Structured Data and Display Models }
AUTHORS { W. L. Hibbard }
PUBLISHEDIN
{
Ph.D. Dissertation, Computer Sciences Department Technical Report 1226,
University of Wisconsin - Madison, May 1995.
}
ABSTRACT
{
In this thesis we develop a system that makes scientific
computations visible and enables physical scientists to perform visual
experiments with their computations. Our approach is unique in the way
it integrates visualization with a scientific programming language. Data
objects of any user-defined data type can be displayed, and can be
displayed in any way that satisfies broad analytic conditions, without
requiring graphics expertise from the user. Furthermore, the system is
highly interactive.

In order to achieve generality in our architecture, we first analyze the nature of scientific data and displays, and the visualization mappings between them. Scientific data and displays are usually approximations to mathematical objects (i.e., variables, vectors and functions) and this provides a natural way to define a mathematical lattice structure on data models and display models. Lattice-structured models provide a basis for integrating certain forms of scientific metadata into the computational and display semantics of data, and also provide a rigorous interpretation of certain expressiveness conditions on the visualization mapping from data to displays. Visualization mappings satisfying these expressiveness conditions are lattice isomorphisms. Applied to the data types of a scientific programming language, this implies that visualization mappings from data aggregates to display aggregates can always be decomposed into mappings of data primitives to display primitives.

These results provide very flexible data and display models, and
provide the basis for flexible and easy-to-use visualization of data objects
occurring in scientific computations.
}
BIBTEX
{
@phdthesis{ Hibbard:1995:phd,
author = "W. L. Hibbard",
title = "Visualizing Scientific Computations: A System based on Lattice-Structured Data and Display Models",
school = "University of Wisconsin",
address = "Madison, WI",
year = 1995}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1994 }
--------------------------------------------------------------
KEY { kutulakos.1994.ijcv }
TITLE { Recovering Shape by Purposive Viewpoint Adjustment }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Int. J. Computer Vision **12**, 1994, 113-136 }
ABSTRACT
{
We present an approach for recovering surface shape from the occluding
contour using an active (i.e., moving) observer. It is based on a
relation between the geometries of a surface in a scene and its
occluding contour: If the viewing direction of the observer is along a
principal direction for a surface point whose projection is on the
contour, surface shape (i.e., curvature) at the surface point can be
recovered from the contour. Unlike previous approaches for recovering
shape from the occluding contour, we use an observer that
*purposefully* changes viewpoint in order to achieve a
well-defined geometric relationship with respect to a 3D shape prior
to its recognition. We show that there is a simple and efficient
viewing strategy that allows the observer to align the viewing
direction with one of the two principal directions for a point on the
surface. This strategy depends on only curvature measurements on the
occluding contour and therefore demonstrates that recovering
quantitative shape information from the contour does not require
knowledge of the velocities or accelerations of the observer.
Experimental results demonstrate that our method can be easily
implemented and can provide reliable shape information from the
occluding contour.
}
BIBTEX
{
@article{kutu:ijcv94,
author = "Kiriakos N. Kutulakos and Charles R. Dyer",
title = "Recovering shape by purposive viewpoint adjustment",
journal = "Int. J. of Computer Vision",
volume = 12,
number = 2,
pages = {113-136},
year = 1994}
}
--------------------------------------------------------------
KEY { kutulakos.1994.ai }
TITLE { Global Surface Reconstruction by Purposive Control of Observer Motion }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Artificial Intelligence **78**, No. 1-2, 1995, 147-177. }
ABSTRACT
{
What viewpoint-control strategies are important for performing global
visual exploration tasks such as searching for specific surface
markings, building a global model of an arbitrary object, or
recognizing an object? In this paper we consider the task of
purposefully controlling the motion of an active, monocular observer
in order to recover a global description of a smooth,
arbitrarily-shaped object. We formulate global surface reconstruction
as the task of controlling the motion of the observer so that the
visible rim slides over the maximal, connected, reconstructible
surface regions intersecting the visible rim at the initial
viewpoint. We show that these regions are bounded by a subset of the
visual event curves defined on the surface.

By studying the epipolar parameterization, we develop two basic
strategies that allow reconstruction of a surface region around any
point in a reconstructible surface region. These strategies control
viewpoint to achieve and maintain a well-defined geometric
relationship with the object's surface, rely only on information
extracted directly from images (e.g., tangents to the occluding
contour), and are simple enough to be performed in real time. We
then show how global surface reconstruction can be provably achieved
by (1) appropriately integrating these strategies to iteratively
``grow'' the reconstructed regions, and (2) obeying four simple
rules.
}
BIBTEX
{
@article{kutu:ai95,
author = "Kiriakos N. Kutulakos and Charles R. Dyer",
title = "Global surface reconstruction by purposive control of observer motion",
journal = "Artificial Intelligence",
pages = {147-177},
volume = 78,
year = 1995}
}
--------------------------------------------------------------
KEY { kutulakos.1994.cvpr.a}
TITLE { Occluding Contour Detection using Affine Invariants and Purposive Viewpoint Control }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1994, 323-330. }
ABSTRACT
{
We present an approach for identifying the occluding contour and
determining its sidedness using an active (i.e., moving) observer. It
is based on the *non-stationarity property* of the visible rim:
When the observer's viewpoint is changed, the visible rim is a
collection of curves that ``slide,'' rigidly or non-rigidly, over the
surface. We show that the observer can deterministically choose three
views on the tangent plane of selected surface points to distinguish
such curves from stationary surface curves (i.e., surface
markings). Our approach demonstrates that the occluding contour can be
identified *directly*, i.e., without first computing surface
shape (distance and curvature).
}
BIBTEX
{
@inproceedings{kutu:cvpr94a,
author = "Kiriakos N. Kutulakos and Charles R. Dyer",
title = "Occluding Contour Detection Using Affine Invariants and Purposive Viewpoint Control",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
year = 1994,
pages = {323-330}}
}
--------------------------------------------------------------
KEY { kutulakos.1994.cvpr.b }
TITLE { Global Surface Reconstruction by Purposive Control of Observer Motion }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1994, 331-338 }
ABSTRACT
{
What real-time, qualitative viewpoint-control behaviors are important
for performing global visual exploration tasks such as searching for
specific surface markings, buildinga global model of an arbitrary
object, or recognizing an object? In this paper we consider the task
of purposefully controlling the motion of an active, monocular
observer in order to recover a global description of a smooth,
arbitrarily-shaped object using the occluding contour. By studying the
epipolar parameterization, we develop two basic behaviors that allow
reconstruction of a patch around any point in a reconstructible
surface region. These behaviors rely only on information extracted
directly from images (e.g., tangents to the occluding contour), and
are simpleenough to be executed in real time. We then show how global
surface reconstruction can be provably achieved by(1) integrating
these behaviors to iteratively "grow" the reconstructed regions, and
(2) obeying four simple rules.
}
BIBTEX
{
@inproceedings{kutu:cvpr94b,
author = "Kiriakos N. Kutulakos and Charles R. Dyer",
title = "Global Surface Reconstruction by Purposive Control of Observer Motion",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
year = 1994,
pages = {331-338}}
}
--------------------------------------------------------------
KEY { kutulakos.1994.cbvw }
TITLE { Building Global Object Models by Purposive Viewpoint Control }
AUTHORS { K. N. Kutulakos, W. B. Seales, and C. R. Dyer }
PUBLISHEDIN { Proc. 2nd CAD-Based Vision Workshop, 1994, 169-182. }
ABSTRACT
{
We present an approach for recovering a global surface model of an
object from the deformation of the occluding contour using an active
(i.e., mobile) observer able to control its motion. In particular, we
consider two problems: (1) How can the observer's viewpoint be
controlled in order to generate a dense sequence of images that allows
incremental reconstruction of an unknown surface, and (2) how can we
construct a global surface model from the generated image sequence?
Solving these two problems is crucial for automatically constructing
models of objects whose surface is non-convex and self-occludes. We
achieve the first goal by *purposefully* and *qualitatively*
controlling the observer's instantaneous direction of motion in order
to control the motion of the visible rim over the surface. We achieve
the second goal by using a calibrated trinocular camera rig and a
mechanism for controlling the relative position and orientation of the
viewed surface with respect to the trinocular rig.
}
BIBTEX
{
@inproceedings{ Kutulakos:1994:cbvw,
author = "Kiriakos N. Kutulakos and W. Brent Seales and Charles R. Dyer",
title = "Building Global Object Models by Purposive Viewpoint Control",
booktitle = "Proc. 2nd CAD-Based Vision Workshop",
year = 1994,
pages = {169--182} }
}
--------------------------------------------------------------
KEY { kutulakos.1994.thesis }
TITLE { Exploring Three-Dimensional Objects by Controlling the Point of Observation }
AUTHORS { K. N. Kutulakos }
PUBLISHEDIN
{
Ph.D. Dissertation, Computer Sciences Department Technical Report 1251,
University of Wisconsin - Madison, October 1994.
}
ABSTRACT
{
In this thesis we study how controlled movements of a camera can be
used to infer properties of a curved object's three-dimensional shape.
The unknown geometry of an environment's objects, the effects of
self-occlusion, the depth ambiguities caused by the projection
process, and the presence of noise in image measurements are a few of
the complications that make object-dependent movements of the camera
advantageous in certain shape recovery tasks. Such movements can
simplify local shape computations such as curvature estimation, allow
use of weaker camera calibration assumptions, and enable the
extraction of global shape information for objects with complex
surface geometry. The utility of object-dependent camera movements is
studied in the context of three tasks, each involving the extraction
of progressively richer information about an object's unknown shape:
(1) detecting the occluding contour, (2) estimating surface curvature
for points projecting to the contour, and (3) building a
three-dimensional model for an object's entire surface. Our main
result is the development of three distinct active vision strategies
that solve these three tasks by controlling the motion of a camera.

Occluding contour detection and surface curvature estimation are achieved by exploiting the concept of a special viewpoint: For any image there exist special camera positions from which the object's view trivializes these tasks. We show that these positions can be deterministically reached, and that they enable shape recovery even when few or no markings and discontinuities exist on the object's surface, and when differential camera motion measurements cannot be accurately obtained.

A basic issue in building three-dimensional global object models is how to control the camera's motion so that previously-unreconstructed regions of the object become reconstructed. A fundamental difficulty is that the set of reconstructed points can change unpredictably (e.g., due to self-occlusions) when ad hoc motion strategies are used. We show how global model-building can be achieved for generic objects of arbitrary shape by controlling the camera's motion on automatically-selected surface tangent and normal planes so that the boundary of the already-reconstructed regions is guaranteed to "slide" over the object's entire surface.

Our work emphasizes the need for (1) controlling camera motion
through efficient processing of the image stream, and (2) designing
provably-correct strategies, i.e., strategies whose success can be
accurately characterized in terms of the geometry of the viewed
object. For each task, efficiency is achieved by extracting from
each image only the information necessary to move the camera
differentially, assuming a dense sequence of images, and using 2D
rather than 3D information to control camera motion. Provable
correctness is achieved by controlling camera motion based on the
occluding contour's dynamic shape and maintaining specific
task-dependent geometric constraints that relate the camera's motion
to the differential geometry of the object.
}
BIBTEX
{
@phdthesis{ Kutulakos:1994:phd,
author = "K. N. Kutulakos",
title = "Exploring Three-Dimensional Objects by Controlling the Point of Observation",
school = "University of Wisconsin",
address = "Madison, WI",
year = 1994}
}
--------------------------------------------------------------
KEY { kutulakos.1994.icra }
TITLE { Provable Strategies for Vision-Guided Exploration in Three Dimensions }
AUTHORS { K. N. Kutulakos, C. R. Dyer, and V. J. Lumelsky }
PUBLISHEDIN { Proc. 1994 IEEE Int. Conf. Robotics and Automation, 1994, 1365-1372. }
ABSTRACT
{
An approach is presented for exploring an unknown, arbitrary surface
in three-dimensional (3D) space by a mobile robot. The main
contributions are (1) an analysis of the capabilities a robot must
possess and the trade-offs involved in the design of an exploration
strategy, and (2) two provably-correct exploration strategies that
exploit these trade-offs and use visual sensors (e.g., cameras and
range sensors) to plan the robot's motion. No such analysis existed
previously for the case of a robot moving freely in 3D space. The
approach exploits the notion of the *occlusion boundary*, i.e.,
the points separating the visible from the occluded parts of an
object. The occlusion boundary is a collection of curves that
``slide'' over the surface when the robot's position is continuously
controlled, inducing the visibility of surface points over which they
slide. The paths generated by our strategies force the occlusion
boundary to slide over the entire surface. The strategies provide a
basis for integrating motion planning and visual sensing under a
common computational framework.
}
BIBTEX
{
@inproceedings{ Kutulakos:1994:icra,
author = "K. N. Kutulakos and Charles R. Dyer and V. J. Lumelsky",
title = "Provable Strategies for Vision-Guided Exploration in Three Dimensions",
booktitle = "Proc. 1994 IEEE Int. Conf. Robotics and Automation",
pages = "1365-1372",
year = 1994}
}
--------------------------------------------------------------
KEY { lai.1994.cvpr }
TITLE { Deformable Contours: Modeling and Extraction }
AUTHORS { K. F. Lai and R. T. Chin }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1994, 601-608. }
ABSTRACT
{
This paper considers the problem of modeling and extracting arbitrary
deformable contours from noisy images. We propose a global contour
model based on a stable and regenerative shape matrix, which is
invariant and unique under rigid motions. Combined with Markov random
field to model local deformations, this yields prior distribution that
exerts influence over a global model while allowing for
deformations. We then cast the problem of extraction into posterior
estimation and show its equivalence to energy minimization of a
generalized active contour model. We discuss pertinent issues in shape
training, energy minimization, line search strategies, minimax
regularization and initialization by generalized Hough
transform. Finally, we present experimental results and compare its
performance to rigid template matching.
}
BIBTEX
{
@inproceedings{ Lai:1994:cvpr,
author = "K. F. Lai and R. T. Chin",
title = "Deformable Contours: Modeling and Extraction",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
pages = "601--608",
year = 1994}
}
--------------------------------------------------------------
KEY { seitz.1994.nram }
TITLE { Detecting Irregularities in Cyclic Motion }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. Workshop on Motion of Non-Rigid and Articulated Objects, 1994, 178-185. }
ABSTRACT
{
Real cyclic motions tend not to be perfectly even, i.e., the period varies
slightly from one cycle to the next, because of physically important changes
in the scene. A generalization of period is defined for cyclic motions
that makes periodic variation explicit. This representation, called the
period trace, is compact and purely temporal, describing the evolution
of an object or scene without reference to spatial quantities such as
position or velocity. By delimiting cycles and identifying correspondences
across cycles, the period trace provides a means of temporally registering
a cyclic motion. In addition, several purely temporal motion features are
derived, relating to the nature and location of irregularities. Results
are presented using real image sequences and applications to athletic and
medical motion analysis are discussed.
}
BIBTEX
{
@inproceedings{seitz:mnao94,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Detecting Irregularities in Cyclic Motion",
booktitle = "Proc. Workshop on Motion of Non-Rigid and Articulated Objects",
pages = {178-185},
year = 1994}
}
--------------------------------------------------------------
KEY { seitz.1994.cvpr }
TITLE { Affine Invariant Detection of Periodic Motion }
AUTHORS { S. M. Seitz and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1994, 970-975. }
ABSTRACT
{
Current approaches for detecting periodic motion assume a stationary camera
and place limits on an object's motion. These approaches rely on the
assumption that a periodic motion projects to a set of periodic image
curves, an assumption that is invalid in general.
Using affine-invariance, we
derive necessary and sufficient conditions for an image sequence to be
the projection of a periodic motion. No restrictions are placed on
either the motion of the camera or the object.
Our algorithm is shown to be provably-correct for
noise-free data and is extended to be robust with respect to
occlusions and noise. The extended algorithm is evaluated with real and
synthetic image sequences.
}
BIBTEX
{
@inproceedings{seitz:cvpr94,
author = "Steven M. Seitz and Charles R. Dyer",
title = "Affine Invariant Detection of Periodic Motion",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
pages = {970-975},
year = 1994}
}
--------------------------------------------------------------
KEY { lai.1994.icarcv }
TITLE { On Classifying Deformable Contours Using the Generalized Active Contour Model }
AUTHORS { K. F. Lai and R. T. Chin }
PUBLISHEDIN { Proc. Int. Conf. Automation, Robotics and Computer Vision, Singapore, 1994. }
ABSTRACT
{
Recently, we proposed the generalized active contour model (g-snake) to model
and extract deformable contours from noisy images. This paper demonstrates the
usefulness of g-snake in classifying among several candidate deformable
contours. The g-snake is suitable for this task because its shape
representation is unique, affine invariant and possesses
metric properties. We derive the
optimal classification test and show that this requires marginalization of the
distribution. However, as the summation is peaked around the posterior estimate
in most practical applications, only small regions need to be considered.
Finally, we performed extensive experimentations and report significant
improvement over matched template in handwritten numeral recognition.
}
BIBTEX
{
@inproceedings{ Lai:1994:icarcv,
author = "K. F. Lai and R. T. Chin",
title = "On Classifying Deformable Contours Using the Generalized Active Contour Model",
booktitle = "Proc. Int. Conf. Automation, Robotics and Computer Vision",
year = 1994}
}
--------------------------------------------------------------
KEY { lai.1994.thesis }
TITLE { Deformable Contours: Modeling, Extraction, Detection and Classification }
AUTHORS { K. F. Lai }
PUBLISHEDIN
{
Ph.D. Dissertation, Electrical and Computer Engineering Department, August 1994.
}
ABSTRACT
{
This thesis presents an integrated approach in modeling, extracting,
detecting and classifying deformable contours directly from noisy
images. We begin by conducting a case study on regularization,
formulation and initialization of the active contour models
(snakes). Using minimax principle, we derive a regularization
criterion whereby the values can be automatically and implicitly
determined along the contour. Furthermore, we formulate a set of
energy functionals which yield snakes that contain Hough transform as
a special case. Subsequently, we consider the problem of modeling and
extracting arbitrary deformable contours from noisy images. We
combine a stable, invariant and unique contour model with Markov
random field to yield prior distribution that exerts influence over
an arbitrary global model while allowing for deformation. Under the
Bayesian framework, contour extraction turns into posterior
estimation, which is in turn equivalent to energy minimization in a
generalized active contour model. Finally, we integrate these lower
level visual tasks with pattern recognition processes of detection and
classification. Based on the Nearman-Pearson lemma, we derive the
optimal detection and classification tests. As the summation is
peaked in most practical applications, only small regions need to be
considered in marginalizing the distribution. The validity of our
formulation have been confirmed by extensive and rigorous
experimentations.
}
BIBTEX
{
@phdthesis{ Lai:1999:phd,
author = "K. F. Lai",
title = "Deformable Contours: Modeling, Extraction, Detection and Classification",
school = "University of Wisconsin",
address = "Madison, WI",
year = 1994}
}
--------------------------------------------------------------
KEY { hibbard.1994.computer }
TITLE { Interactive Visualization of Earth and Space Science Computations }
AUTHORS { W. L. Hibbard, B. E. Paul, A. L. Battaiola, D. A. Santek, M-F. Voidrot-Martinez, and C. R. Dyer }
PUBLISHEDIN { Computer** 27**, No. 7, July 1994, 65-72. }
ABSTRACT
{
We describe techniques that enable Earth and space scientists
to interactively visualize and experiment with their computations.
Numerical simulations of the Earth's atmosphere and oceans generate
large and complex data sets, which we visualize in a highly interactive
virtual Earth environment. We use data compression and distributed
computing to maximize the size of simulations that can be explored,
and a user interface tuned to the needs of environmental modelers.
For the broader class of computations used by scientists we have
developed more general techniques, integrating visualization with an
environment for developing and executing algorithms. The key is
providing a flexible data model that lets users define data types
appropriate for their algorithms, and also providing a display model
that lets users visualize those data types without placing a substantial
burden of graphics knowledge on them.
}
BIBTEX
{
@article{ Hibbard:1994:computer,
author = "W. L. Hibbard and B. E. Paul and A. L. Battaiola and D. A. Santek and M-F. Voidrot-Martinez and C. R. Dyer",
title = "Interactive Visualization of Earth and Space Science Computations",
journal = "Computer",
volume = "27",
number = "7",
month = "July",
year = "1994",
pages = "65--72"}
}
--------------------------------------------------------------
KEY { hibbard.1994.vis }
TITLE { A Lattice Model for Data Display }
AUTHORS { W. L. Hibbard, C. R. Dyer, and B. E. Paul }
PUBLISHEDIN { Proc. Visualization '94, 1994, 310-317. }
ABSTRACT
{
In order to develop a foundation for visualization, we develop
lattice models for data objects and displays that focus on the fact that
data objects are approximations to mathematical objects and real
displays are approximations to ideal displays. These lattice models
give us a way to quantize the information content of data and displays
and to define conditions on the visualization mappings from data to
displays. Mappings satisfy these conditions if and only if they are
lattice isomorphisms. We show how to apply this result to scientific
data and display models, and discuss how it might be applied to
recursively defined data types appropriate for complex information
processing.
}
BIBTEX
{
@inproceedings{ Hibbard:1994:vis,
author = "W. L. Hibbard and Charles R. Dyer and B. E. Paul",
title = "A Lattice Model for Data Display",
booktitle = "Proc. Visualization '94",
pages = "310--317",
year = 1994}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1993 }
--------------------------------------------------------------
KEY { kutulakos.1993.cvpr }
TITLE { Toward Global Surface Reconstruction by Purposive Viewpoint Adjustment }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1993, 726-727. }
ABSTRACT
{
We consider the following problem: How should an observer change viewpoint
in order to generate a dense image sequence of an arbitrary smooth surface
so that it can be incrementally reconstructed using the occluding contour
and the epipolar parameterization? We present a collection of qualitative
behaviors that, when integrated appropriately, purposefully control
viewpoint based on the appearance of the surface in order to provably solve
this problem.
}
BIBTEX
{
@inproceedings{ Kutulakos:1993:cvpr,
author = "K. N. Kutulakos and C. R. Dyer",
title = "Toward Global Surface Reconstruction by Purposive Viewpoint Adjustment",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
year = 1993,
pages = {726--727} }
}
--------------------------------------------------------------
KEY { kutulakos.1993.icra }
TITLE { Vision-Guided Exploration: A Step toward General Motion Planning in Three Dimensions }
AUTHORS { K. N. Kutulakos, V. J. Lumelsky, and C. R. Dyer }
PUBLISHEDIN { Proc. 1993 IEEE Int. Conf. on Robotics and Automation, 1993, 289-296. }
ABSTRACT
{
We present an approach for solving the path planning problem for a mobile
robot operating in an unknown, three dimensional environment containing
obstacles of arbitrary shape. The main contributions of this paper are (1)
an analysis of the type of sensing information that is necessary and
sufficient for solving the path planning problem in such environments, and
(2) the development of a framework for designing a provably-correct
algorithm to solve this problem. Working from first principles, without any
assumptions about the environment of the robot or its sensing capabilities,
our analysis shows that the ability to explore the obstacle surfaces (i.e.,
to make all their points visible) is intrinsically linked with the ability
to plan the motion of the robot. We argue that current approaches to the
path planning problem with incomplete information simply do not extend to
the general three-dimensional case, and that qualitatively different
algorithms are needed.
}
BIBTEX
{
@inproceedings{ Kutulakos:1993:icra,
author = "K. N. Kutulakos and V. J. Lumelsky and Charles R. Dyer",
title = "Vision-Guided Exploration: A Step toward General Motion Planning in Three Dimensions",
booktitle = "Proc. 1993 IEEE Int. Conf. on Robotics and Automation",
pages = "289--296",
year = 1993}
}
--------------------------------------------------------------
KEY { allmen.1993.cvgip }
TITLE { Computing Spatiotemporal Relations for Dynamic Perceptual Organization }
AUTHORS { M. Allmen and C. R. Dyer }
PUBLISHEDIN { Computer Vision, Graphics and Image Processing: Image Understanding** 58**, 1993, 338-351 }
ABSTRACT
{
To date, the overwhelming use of motion in computational vision has
been to recover the three-dimensional structure of the scene. We
propose that there are other, more powerful, uses for motion. Toward
this end, we define dynamic perceptual organization as an extension of
the traditional (static) perceptual organization approach. Just as
static perceptual organization groups coherent features in an image,
dynamic perceptual organization groups coherent motions through an
image sequence. Using dynamic perceptual organization, we propose a
new paradigm for motion understanding and show why it can be done
independently of the recovery of scene structure and scene motion.
The paradigm starts with a spatiotemporal cube of image data and
organizes the paths of points so that interactions between the paths
and perceptual motions such as common, relative and cyclic are made
explicit. The results of this can then be used for high-level motion
recognition tasks.
}
BIBTEX
{
@article{ Allmen:1993:cvgip,
author = "M. Allmen and C. R. Dyer",
title = "Computing Spatiotemporal Relations for Dynamic Perceptual Organization",
journal = "Computer Vision, Graphics and Image Processing: Image Understanding",
volume = "58",
year = "1993",
pages = "338--351"}
}
--------------------------------------------------------------
KEY { waldon.1993.wqv }
TITLE { Dynamic Shading, Motion Parallax and Qualitative Shape }
AUTHORS { S. Waldon and C. R. Dyer }
PUBLISHEDIN { Proc. IEEE Workshop on Qualitative Vision, 1993, 61-70. }
ABSTRACT
{
We address the problem of qualitative shape
recovery from moving surfaces. Our analysis is unique in that we
consider specular interreflections and explore the effects of both
motion parallax and changes in shading. To study this situation we
define an image flow field called the reflection flow field,
which describes the motion of reflection points and the motion of the
surface. From a kinematic analysis, we show that the reflection flow
is qualitatively different from the motion parallax because it is
discontinuous at or near parabolic curves. We also show that when the
gradient of the reflected image is strong, gradient-based flow
measurement techniques approximate the reflection flow field and not
the motion parallax. We conclude from these analyses that reliable
qualitative shape information is generally available only at
discontinuities in the image flow field.
}
BIBTEX
{
@inproceedings{ Waldon:1993:wqv,
author = "S. Waldon and Charles R. Dyer",
title = "Dynamic Shading, Motion Parallax and Qualitative Shape",
booktitle = "Proc. IEEE Workshop on Qualitative Vision",
pages = "61--70",
year = 1993}
}
--------------------------------------------------------------
KEY { eggert.1993.pami }
TITLE { The Scale Space Aspect Graph }
AUTHORS { D. W. Eggert, K. W. Bowyer, C. R. Dyer, H. I. Christensen, and D. B. Goldgof }
PUBLISHEDIN { IEEE Trans. Pattern Analysis and Machine Intelligence** 15**, 1993, 1114-1130. }
ABSTRACT
{
Currently the aspect graph is computed from the theoretical standpoint
of perfect resolution in object shape, the viewpoint and the projected image.
This means that the aspect graph may include details that an observer could
never see in practice. Introducing the notion of scale into the aspect graph
framework provides a mechanism for selecting a level of detail that is
"large enough" to merit explicit representation. This effectively allows
control over the number of nodes retained in the aspect graph. This paper
introduces the concept of the scale space aspect graph, defines three
different interpretations of the scale dimension, and presents a detailed
example for a simple class of objects, with scale defined in terms of the
spatial extent of features in the image.
}
BIBTEX
{
@article{ Eggert:1993:pami,
author = "D. W. Eggert and K. W. Bowyer and C. R. Dyer and H. I. Christensen and D. B. Goldgof",
title = "The Scale Space Aspect Graph",
journal = "IEEE Trans. Pattern Analysis and Machine Intelligence",
volume = "15",
year = "1993",
pages = "1114--1130"}
}
--------------------------------------------------------------
KEY { lai.1993.accv }
TITLE { On Regularization, Formulation and Initialization of Active Contour Models (Snakes) }
AUTHORS { K. F. Lai and R. T. Chin }
PUBLISHEDIN { Proc. 1st Asian Conf. on Computer Vision, 1993, 542-545. }
ABSTRACT
{
In snake formulation, large regularization enhances the robustness against noise
and incomplete data, while small values increase the accuracy in capturing
boundary variations. We present a local minimax criterion which automatically
determines the optimal regularization at every locations along the boundary with
no added computation cost. We also modify existing energy formulations to repair
deficiencies in internal energy and improve performance in external energy. This
yields snakes that contain Hough transform as a special case. We can therefore
initialize the snake efficiently and reliably using Hough transform.
}
BIBTEX
{
@inproceedings{ Lai:1993:accv,
author = "K. F. Lai and Charles R. Dyer",
title = "On Regularization, Formulation and Initialization of Active Contour Models (Snakes)",
booktitle = "Proc. 1st Asian Conf. on Computer Vision",
pages = "542--545",
year = 1993}
}
--------------------------------------------------------------
KEY { kutulakos.1993.spie }
TITLE { Building Global Object Models by Purposive Viewpoint Control }
AUTHORS { K. N. Kutulakos, W. B. Seales, and C. R. Dyer }
PUBLISHEDIN { Proc. SPIE: Sensor Fusion VI, 1993, 368-383. }
ABSTRACT
{
We present an approach for recovering a global surface model of an
object from the deformation of the occluding contour using an active
(i.e., mobile) observer able to control its motion. In particular, we
consider two problems: (1) How can the observer's viewpoint be
controlled in order to generate a dense sequence of images that allows
incremental reconstruction of an unknown surface, and (2) how can we
construct a global surface model from the generated image sequence? We
achieve the first goal by purposefully and qualitatively controlling
the observer's instantaneous direction of motion in order to control
the motion of the visible rim over the surface. We achieve the second
goal by using a stationary calibrated trinocular camera rig and a
mechanism for controlling the relative position and orientation of the
viewed surface with respect to the trinocular rig. Unlike previous
shape-from-motion approaches which derive quantitative shape
information from an arbitrarily generated sequence of images, we
develop a collection of simple and efficient viewing strategies that
allow the observer to achieve the global reconstruction goal by
maintaining specific geometric relationships with the viewed
surface. These relationships depend only on tangent computations on
the occluding contour. To demonstrate the feasibility and
effectiveness of our approach we apply the developed algorithms to
synthetic and real scenes.
}
BIBTEX
{
@inproceedings{ Kutulakos:1993:spie,
author = "K. N. Kutulakos and W. B. Seales and Charles R. Dyer",
title = "Building Global Object Models by Purposive Viewpoint Control",
booktitle = "Proc. SPIE: Sensor Fusion VI",
pages = "368--383",
year = 1993}
}
--------------------------------------------------------------
KEY { kutulakos.1993.tr1141 }
TITLE { Global Surface Reconstruction by Purposive Control of Observer Motion }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN
{
Computer Sciences Department Technical Report 1141,
University of Wisconsin - Madison, April 1993.
}
ABSTRACT
{
What real-time, qualitative viewpoint-control behaviors are important
for performing global visual exploration tasks such as searching for
specific surface markings, building a global model of an arbitrary
object, or recognizing an object? In this paper we consider the task
of purposefully controlling the motion of an active, monocular
observer in order to recover a global description of a smooth,
arbitrarily-shaped object.

We formulate global surface reconstruction as the qualitative task of controlling the motion of the observer so that the visible rim slides over the maximal, connected, reconstructible surface regions intersecting the visible rim at the initial viewpoint. We show that these regions are bounded by a subset of the visual event curves defined on the surface.

By studying the epipolar parameterization, we develop four basic
behaviors that allow reconstruction of a surface patch around any
point in a reconstructible surface region. These behaviors control
viewpoint to achieve and maintain a well-defined geometric
relationship with the object's surface, rely only on information
extracted directly from images (e.g., tangents to the occluding
contour), and are simple enough to be executed in real time. We then
show how global surface reconstruction can be provably achieved by (1)
appropriately integrating these behaviors to iteratively "grow" the
reconstructed regions, and (2) obeying four simple rules.
}
NOTES { *A longer version.* }
BIBTEX
{
@techreport{ Kutulakos:1993:tr,
author = "K. N. Kutulakos and Charles R. Dyer",
title = "Global Surface Reconstruction by Purposive Control of Observer Motion",
institution = "Computer Sciences Department, University of Wisconsin-Madison",
number = "1141",
month = "April",
year = 1993}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1992 }
--------------------------------------------------------------
KEY { kutulakos.1992.cvpr }
TITLE { Recovering Shape by Purposive Viewpoint Adjustment }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1992, 16-22. }
ABSTRACT
{
We present an approach for recovering surface shape from the occluding
contour using an active (i.e., moving) observer. It is based on a
relation between the geometries of a surface in a scene and its
occluding contour: If the viewing direction of the observer is along a
principal direction for a surface point whose projection is on the
contour, surface shape (i.e., curvature) at the surface point can be
recovered from the contour. Unlike previous approaches for recovering
shape from the occluding contour, we use an observer that purposefully
changes viewpoint in order to achieve a well-defined geometric
relationship with respect to a 3D shape prior to its recognition. We
show that there is a simple and efficient viewing strategy that allows
the observer to align the viewing direction with one of the two
principal directions for a point on the surface. Experimental results
demonstrate that our method can be easily implemented and can provide
reliable shape information.
}
BIBTEX {
@inproceedings{ Kutulakos:1992:cvpr,
author = "K. N. Kutulakos and Charles R. Dyer",
title = "Recovering Shape by Purposive Viewpoint Adjustment",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
pages = "16--22",
year = 1992}
}
--------------------------------------------------------------
KEY { kutulakos.1992.tr1124 }
TITLE { Object Exploration By Purposive, Dynamic Viewpoint Adjustment }
AUTHORS { K. N. Kutulakos, C. R. Dyer, V. J. Lumelsky }
PUBLISHEDIN
{
Computer Sciences Department Technical Report 1124,
University of Wisconsin - Madison, November 1992.
}
ABSTRACT
{
We present a viewing strategy for exploring the surface of an unknown
object (i.e., making all of its points visible) by purposefully
controlling the motion of an active observer. It is based on a simple
relation between (1) the instantaneous direction of motion of the
observer, (2) the visibility of points projecting to the occluding
contour, and (3) the surface normal at those points: If the dot product of
the surface normal at such points and the observer's velocity is positive,
the visibility of the points is guaranteed under an infinitesimal
viewpoint change. We show that this leads to an object exploration
strategy in which the observer *purposefully* controls its motion
based on the occluding contour in order to impose structure on the set of
surface points explored, make its representation simple and qualitative,
and provably solve the exploration problem for smooth generic surfaces of
arbitrary shape. Unlike previous approaches where exploration is cast as a
discrete process (i.e., asking where to look next?) and where the
successful exploration of arbitrary objects is not guaranteed, our
approach demonstrates that dynamic viewpoint control through directed
observer motion leads to a qualitative exploration strategy that is
provably-correct, depends only on the dynamic appearance of the
occluding contour, and does not require the recovery of detailed
three-dimensional shape descriptions from every position of the observer.
}
BIBTEX
{
@techreport{ Kutulakos:1992:tr,
author = "K. N. Kutulakos and Charles R. Dyer",
title = "Object Exploration By Purposive, Dynamic Viewpoint Adjustment",
institution = "Computer Sciences Department, University of Wisconsin-Madison",
number = "1124",
month = "November",
year = 1992}
}
--------------------------------------------------------------
KEY { eggert.1992.cvpr }
TITLE { The Scale Space Aspect Graph }
AUTHORS { D. W. Eggert, K. W. Bowyer, C. R. Dyer, H. I. Christensen, and D. B. Goldgof }
PUBLISHEDIN { Proc. Computer Vision and Pattern Recognition Conf., 1992, 335-340. }
ABSTRACT
{
Currently the aspect graph is computed from the theoretical standpoint
of perfect resolution in the viewpoint, the projected image and the
object shape. This means that the aspect graph may include details
that an observer could never see in practice. Introducing the notion
of scale into the aspect graph framework provides a mechanism for
selecting a level of detail that is "large enough" to merit explicit
representation. This effectively allows control over the number of
nodes retained in the aspect graph. This paper introduces the concept
of the scale space aspect graph, defines an interpretation of the
scale dimension in terms of the spatial extent of features in the
image and presents a detailed example for a simple class of objects.
}
BIBTEX
{
@inproceedings{ Eggert:1992:cvpr,
author = "D. W. Eggert and K. W. Bowyer and Charles R. Dyer and H. I. Christensen and D. B. Goldgof",
title = "The Scale Space Aspect Graph",
booktitle = "Proc. Computer Vision and Pattern Recognition Conf.",
pages = "335--340",
year = 1992}
}
--------------------------------------------------------------
KEY { seales.1992.cvgip }
TITLE { Viewpoint from Occluding Contour }
AUTHORS { W. B. Seales and C. R. Dyer }
PUBLISHEDIN { Computer Vision, Graphics and Image Processing: Image Understanding** 55**, 1992, 198-211. }
ABSTRACT
{
In this paper we present the geometry and the algorithms for organizing a
viewer-centered representation of the occluding contour of polyhedra.
The contour is computed from a polyhedral boundary model as it would appear
under orthographic projection into the image plane from every viewpoint
on the view sphere.
Using this representation, we show how to derive constraints on regions in
viewpoint space from the relationship between detected image features and
our precomputed contour model.
Such constraints are based on both qualitative (viewpoint extent) and
quantitative (angle measurements and relative geometry) information that has
been precomputed about how the contour appears in the image plane as a set
of projected curves and T-junctions from self-occlusion.
The results we show from an experimental system demonstrate that features
of the occluding contour can be computed in a model-based framework,
and their geometry constrains the viewpoints from which a model will project
to a set of occluding contour features in an image.
}
BIBTEX
{
@article{ Seales:1992:cvgip,
author = "W. B. Seales and C. R. Dyer",
title = "Viewpoint from Occluding Contour",
journal = "Computer Vision, Graphics and Image Processing: Image Understanding",
volume = "55",
year = "1992",
pages = "198--211"}
}
--------------------------------------------------------------
KEY { seales.1992.ecai }
TITLE { An Occlusion-Based Representation of Shape for Viewpoint Recovery }
AUTHORS { W. B. Seales and C. R. Dyer }
PUBLISHEDIN { Proc. 10th European Conf. on Artificial Intelligence, 1992, 816-820. }
ABSTRACT
{
In this paper we present the geometry and the algorithms for
organizing and using a viewer-centered representation of the occluding
contour of polyhedra. The representation is computed from a
polyhedral model under orthographic projection for all viewing
directions. Using this representation, we derive constraints on
viewpoint correspondences between image features and model contours.
Our results show that the occluding contour, computed in a model-based
framework, can be used to strongly constrain the viewpoints where a 3D
model matches the occluding contour features of the image.
}
BIBTEX
{
@inproceedings{ Seales:1992:ecai,
author = "W. B. Seales and Charles R. Dyer",
title = "An Occlusion-Based Representation of Shape for Viewpoint Recovery",
booktitle = "Proc. 10th European Conf. on Artificial Intelligence",
pages = "816--820",
year = 1992}
}
--------------------------------------------------------------
KEY { hibbard.1992.vis }
TITLE { Display of Scientific Data Structures for Algorithm Visualization }
AUTHORS { W. Hibbard, C. R. Dyer, and B. Paul }
PUBLISHEDIN { Proc. Visualization '92, 1992, 139-146. }
ABSTRACT
{
We present a technique for defining graphical depictions for all
the data types defined in an algorithm. The ability to display arbitrary
combinations of an algorithm's data objects in a common frame of
reference, coupled with interactive control of algorithm execution,
provides a powerful way to understand algorithm behavior. Type
definitions are constrained so that all primitive values occurring in data
objects are assigned scalar types. A graphical display, including user
interaction with the display, is modeled by a special data type.
Mappings from the scalar types into the display model type provide a
simple user interface for controlling how all data types are depicted,
without the need for type-specific graphics logic.
}
BIBTEX
{
@inproceedings{ Hibbard:1992:vis,
author = "W. Hibbard and Charles R. Dyer and B. Paul",
title = "Display of Scientific Data Structures for Algorithm Visualization",
booktitle = "Proc. Visualization '92",
pages = "139--146",
year = 1992}
}
--------------------------------------------------------------
KEY { allmen.1992.tr1130 }
TITLE { Computing Spatiotemporal Relations for Dynamic Perceptual Organization }
AUTHORS { M. Allmen and C. R. Dyer }
PUBLISHEDIN
{
Computer Sciences Department Technical Report 1130,
University of Wisconsin - Madison, December 1992.
}
ABSTRACT
{
To date, the overwhelming use of motion in computational vision has
been to recover the three-dimensional structure of the scene. We
propose that there are other, more powerful, uses for motion. Toward
this end, we define dynamic perceptual organization as an extension of
the traditional (static) perceptual organization approach. Just as
static perceptual organization groups coherent features in an image,
dynamic perceptual organization groups coherent motions through an
image sequence. Using dynamic perceptual organization, we propose a
new paradigm for motion understanding and show why it can be done
independently of the recovery of scene structure and scene motion. The
paradigm starts with a spatiotemporal cube of image data and organizes
the paths of points so that interactions between the paths and
perceptual motions such as common, relative and cyclic are made
explicit. The results of this can then be used for high-level motion
recognition tasks.
}
BIBTEX
{
@techreport{ Allmen:1992:tr,
author = "M. Allmen and Charles R. Dyer",
title = "Computing Spatiotemporal Relations for Dynamic Perceptual Organization",
institution = "Computer Sciences Department, University of Wisconsin-Madison",
number = "1130",
month = "December",
year = 1992}
}
--------------------------------------------------------------
##############################################################
##############################################################
##############################################################
YEAR { 1991 }
--------------------------------------------------------------
KEY { kutulakos.1991.tr1035 }
TITLE { Recovering Shape by Purposive Viewpoint Adjustment }
AUTHORS { K. N. Kutulakos and C. R. Dyer }
PUBLISHEDIN
{
Computer Sciences Department Technical Report 1035,
University of Wisconsin - Madison, August 1991.
}
ABSTRACT
{
We present an approach for recovering surface shape from the occluding
contour using an active (i.e., moving) observer. It is based on a
relation between the geometries of a surface in a scene and its
occluding contour: If the viewing direction of the observer is along a
principal direction for a surface point whose projection is on the
contour, surface shape (i.e., curvature) at the surface point can be
recovered from the contour. Unlike previous approaches for recovering
shape from the occluding contour, we use an observer that purposefully
changes viewpoint in order to achieve a well-defined geometric
relationship with respect to a 3D shape prior to its recognition. We
show that there is a simple and efficient viewing strategy that allows
the observer to align their viewing direction with one of the two
principal directions for a point on the surface. This strategy depends
on only curvature measurements on the occluding contour and therefore
demonstrates that recovering quantitative shape information from the
contour does not require knowledge of the velocities or accelerations
of the observer. Experimental results demonstrate that our method can
be easily implemented and can provide reliable shape information from
the occluding contour.
}
BIBTEX
{
@techreport{ Kutulakos:1991:tr,
author = "K. N. Kutulakos and Charles R. Dyer",
title = "Recovering Shape by Purposive Viewpoint Adjustment",
institution = "Computer Sciences Department, University of Wisconsin-Madison",
number = "1035",
month = "August",
year = 1991}
}
--------------------------------------------------------------
KEY { allmen.1991.thesis }
TITLE { Image Sequence Description using Spatiotemporal Flow Curves: Toward Motion-Based Recognition }
AUTHORS { M. C. Allmen }
PUBLISHEDIN
{
Ph.D. Dissertation, Computer Sciences Department Technical Report 1040,
University of Wisconsin - Madison, August 1991.
}
ABSTRACT
{
Recovering a hierarchical motion description of a long image sequence
is one way to recognize objects and their motions. Intermediate-level
and high-level motion analysis, i.e., recognizing a coordinated
sequence of events such as walking and throwing, has been formulated
previously as a process that follows high-level object
recognition. This thesis develops an alternative approach to
intermediate-level and high-level motion analysis. It does not depend
on complex object descriptions and can therefore be computed prior to
object recognition. Toward this end, a new computational framework for
low and intermediate-level processing of long sequences of images is
presented.

Our new computational framework uses spatiotemporal (ST) surface flow and ST flow curves. As contours move, their projections into the image also move. Over time, these projections sweep out ST surfaces. Thus, these surfaces are direct representations of object motion. ST surface flow is defined as the natural extension of optical flow to ST surfaces. For every point on an ST surface, the instantaneous velocity of that point on the surface is recovered. It is observed that arc length of a rigid contour does not change if that contour is moved in the direction of motion on the ST surface. Motivated by this observation, a function measuring arc length change is defined. The direction of motion of a contour undergoing motion parallel to the image plane is shown to be perpendicular to the gradient of this function.

ST surface flow is then used to recover ST flow curves. ST flow curves are defined such that the tangent at a point on the curve equals the ST surface flow at that point. ST flow curves are then grouped so that each cluster represents a temporally-coherent structure, i.e., structures that result from an object or surface in the scene undergoing motion. Using these clusters of ST flow curves, separate moving objects in the scene can be hypothesized and occlusion and disocclusion between them can be identified.

The problem of detecting cyclic motion, while recognized by the psychology community, has received very little attention in the computer vision community. In order to show the representational power of ST flow curves, cyclic motion is detected using ST flow curves without prior recovery of complex object descriptions. } BIBTEX { @phdthesis{ Allmen:1991:phd, author = "M. C. Allmen", title = "Image Sequence Description using Spatiotemporal Flow Curves: Toward Motion-Based Recognition", school = "University of Wisconsin", address = "Madison, WI", year = 1991} } -------------------------------------------------------------- KEY { seales.1991.thesis } TITLE { Appearance Models of Three-Dimensional Shape for Machine Vision and Graphics } AUTHORS { W. B. Seales } PUBLISHEDIN { Ph.D. Dissertation, Computer Sciences Department Technical Report 1042, University of Wisconsin - Madison, August 1991. } ABSTRACT { A fundamental problem common to both computer graphics and model-based computer vision is how to efficiently model the appearance of a shape. Appearance is obtained procedurally by applying a projective transformation to a three-dimensional object-centered shape representation. This thesis presents a viewer-centered representation that is based on the visual event, a viewpoint where a specific change in the structure of the projected model occurs. We present and analyze the basis of this viewer-centered representation and the algorithms for its construction. Variations of this visual-event-based representation are applied to two specific problems: hidden line/surface display, and the solution for model pose given an image contour.

The problem of how to efficiently display a polyhedral scene over a path of viewpoints is cast as a problem of computing visual events along that path. A visual event is a viewpoint that causes a change in the structure of the image structure graph, a model's projected line drawing. The information stored with a visual event is sufficient to update a representation of the image structure graph. Thus the visible lines of a scene can be displayed as viewpoint changes by first precomputing and storing visual events, and then using those events at display time to interactively update the image structure graph. Display rates comparable to wire-frame display are achieved for large polyhedral models.

The rim appearance representation is a new, viewer-centered, exact representation of the occluding contour of polyhedra. We present an algorithm based on the geometry of polyhedral self-occlusion and on visual events for computing a representation of the exact appearance of occluding contour edges. The rim appearance representation, organized as a multi-level model of the occluding contour, is used to constrain the viewpoints of a three-dimensional model that can produce a set of detected occluding-contour features. Implementation results demonstrate that precomputed occluding-contour information efficiently and tightly constrains the pose of a model while consistently accounting for detected occluding-contour features. } BIBTEX { @phdthesis{ Seales:1991:phd, author = "W. B. Seales", title = "Appearance Models of Three-Dimensional Shape for Machine Vision and Graphics", school = "University of Wisconsin", address = "Madison, WI", year = 1991} } -------------------------------------------------------------- ############################################################## ############################################################## ############################################################## THREAD { manning.2000.tr1417, manning.2001.iccv } -------------------------------------------------------------- THREAD { seitz.1999.ijcv, seitz.1997.cvpr, seitz.1997.iuw.b } -------------------------------------------------------------- THREAD { manning.1999.cvpr, manning.1998.iuw, manning.1998.tr1387 } -------------------------------------------------------------- THREAD { kutulakos.1993.spie, kutulakos.1994.cbvw } -------------------------------------------------------------- THREAD { seitz.1998.iccv, seitz.1997.rochester } -------------------------------------------------------------- THREAD { lai.1994.cvpr, lai.1995.pami } -------------------------------------------------------------- THREAD { kutulakos.1994.ijcv, kutulakos.1992.cvpr, kutulakos.1991.tr1035 } -------------------------------------------------------------- THREAD { kutulakos.1994.ai, kutulakos.1994.cvpr.b, kutulakos.1993.tr1141 } -------------------------------------------------------------- THREAD { allmen.1993.cvgip, allmen.1992.tr1130 } -------------------------------------------------------------- THREAD { eggert.1993.pami, eggert.1992.cvpr }