OpenRaiser/Intern-Atlas huggingface dataset:
Interpolating cubic spline contours by minimizing second derivative discontinuity
Authors: Saeid Tehrani, Terry E. Weymouth, Brian G. Schunck
Venue: ICCV
Year: 1990

It is shown how a contour can be estimated from a few edge positions. The technique fits a cubic spline to edges using the position and orientations of edges (tangent slopes) and computes tangent magnitudes by a minimization based on the second derivatives. Cubic splines (piecewise third-order polynomials) are used because they are the lowest-order polynomials that can deal with inflection points. For assuring a smooth overall contour, the polynomial segments are joined such that the continuity of the first derivative is preserved and discontinuity in the second derivative is minimized. This technique can be used as an efficient means for entering and editing contours which are tied to the underlying data through the edge orientations. The time required for computing the edge orientations and the time for finding the curve parameters are linearly proportional to the number of edge fragments. The algorithm was applied to medical images, and the results are compared with the conic splines and the B-splines and the distance approximation to the cubic splines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Dynamic 3D models with local and global deformations: deformable superquadrics
Authors: Demetri Terzopoulos, Dimitris N. Metaxas
Venue: ICCV
Year: 1990

A physically-based approach is presented to fitting complex 3D shapes using a novel class of dynamic models. These models can deform both locally and globally. The authors formulate deformable superquadrics which incorporate the global shape parameters of a conventional superellipsoid with the local degrees of freedom of a spline. The local/global representational power of a deformable superquadric simultaneously satisfies the conflicting requirements of shape reconstruction and shape recognition. The model's six global deformational degrees of freedom capture gross shape features from visual data and provide salient part descriptors for efficient indexing into a database of stored models. Model fitting experiments involving 2D monocular image data and 3D range data are reported.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Analysis of facial images using physical and anatomical models
Authors: Demetri Terzopoulos, Keith Waters
Venue: ICCV
Year: 1990

A novel approach is presented to the analysis of dynamic facial images. The approach exploits a realistic model of the human face. The face model, which may be simulated and rendered at interactive rates on a graphics workstation, incorporates a physically-based approximation to facial tissue and a set of anatomically-motivated facial muscle actuators. The authors consider the estimation of dynamic facial muscle contractions from video sequences of expressive human faces. They develop an estimation technique that uses deformable contour models to track the nonrigid motions of facial features in images. The technique computes robust muscle actuator controls, enabling the face model to resynthesize transient expressions accurately.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Geometrical learning from multiple stereo views through monocular based feature grouping
Authors: Eric Thirion, Long Quan
Venue: ICCV
Year: 1990

A geometrical learning system is described which constructs automatically the geometric model of indoor environments from multiple stereo views. The produced model includes not only 3-D segments initially provided by a stereo vision system, but also 3-D feature groups. Feature grouping helps to predict the position of a given view with respect to the current model and allows one to correct noisy features by the geometric constraints of feature groups. This 3-D feature grouping is based on a monocular process working on the 2-D segments associated with one source image of a stereo view. Experimental results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Dynamic stereo with self-calibration
Authors: Arun P. Tirumalai, Brian G. Schunck, Ramesh C. Jain
Venue: ICCV
Year: 1990

Dynamic stereo is useful for constructing a complete map of the environment as only a portion of the actual environment is visible from each viewpoint. In addition, there is usually an overlap between the portions of the environment visible from two successive viewpoints. It is then feasible to utilize a prediction-verification approach to combine the individual depth estimates of features visible from both viewpoints to obtain a more accurate estimate. A fundamental requirement for such an approach to be used is accurate knowledge of the camera motion between the two viewpoints. A robust least median of squares (LMS)-based algorithm to recover this motion which provides a self-calibration mechanism is presented. The recovered motion is utilized for recursive disparity prediction and refinement using a robustified Kalman filter formulation. Results are presented for a laboratory stereo sequence.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Occlusion detection in early vision
Authors: Peng-Seng Toh, Andrew K. Forrest
Venue: ICCV
Year: 1990

The authors show that occlusion can be detected by early visual processes derived directly from the image data. Two methods are demonstrated. The first method is based on detecting binocular rivalry during binocular fixation. The feasibility of this technique also supports the hypothesis that stereo fusion and rivalry coexist in human vision. Stereo fusion gives rise to smooth disparity whereas rivalry signals depth discontinuity. The second method uses focal information that results from a change in depth of field. This method does not involve changes of viewpoint and hence avoids the correspondence problem. These two methods together with cues from motion, as has been suggested elsewhere, form robust occlusion detection in early visual processing.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Shape and motion without depth
Authors: Carlo Tomasi, Takeo Kanade
Venue: ICCV
Year: 1990

Inferring the depth and shape of remote objects and the camera motion from a sequence of images is possible in principle, but is an ill-conditioned problem when the objects are distant with respect to their size. This problem is overcome by inferring shape and motion without computing depth as an intermediate step. On a single epipolar plane, an image sequence can be represented by the F*P matrix of the image coordinates of P points tracked through F frames. It is shown that under orthographic projection this matrix is of rank three. Using this result, the authors develop a shape-and-motion algorithm based on singular value decomposition. The algorithm gives accurate results, without relying on any smoothness assumption for either shape or motion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Image interpretation using multi-relational grammars
Authors: Staffan Truvé
Venue: ICCV
Year: 1990

An approach to computational vision that is based on multiple levels of interpretation is presented. The step between each level is seen as taking place in three stages-parsing (in which features and groups of features in an image are given labels), interpreting (in which several interpretations are built, assuring that each feature is given at most one explanation in terms of a higher-level label), and pruning (in which some interpretations are discarded because of global constraints). The parsing and pruning steps are guided by multirelational grammars, a generalization of ordinary attribute grammars and of graph grammars. A bottom-up parsing algorithm for this class of grammars is presented, and their usefulness in image interpretation is illustrated by examples using both synthetic and real-world data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
An approach to color constancy using multiple images
Authors: Masato Tsukada, Yuichi Ohta
Venue: ICCV
Year: 1990

A novel computational algorithm is proposed for color constancy suitable to robot vision. A robot, or a computer, can exactly memorize image information observed in the past. Then it is natural to use more than one image to achieve color constancy. In the algorithm, it is possible to recover the illumination color and the reflectance color only based on the RGB values of two objects identified on two images. It requires no specific assumption on the scene. Experiments show the validity of the proposed algorithm.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Shape from contour: straight homogeneous generalized cones
Authors: Fatih Ulupinar, Ramakant Nevatia
Venue: ICCV
Year: 1990

The authors analyze the properties of straight homogeneous generalized cones (SHGCs) and derive the types of symmetries, that the limb boundaries and cross sections of these objects produce on the image plane. The constraints on the 3-D shape of the objects are formulated based on the symmetries and from the geometry of the projection models. Finally the methods that recover the 3-D shape from the image of their contours are discussed and recovered surfaces are shown for sample objects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Appearance-model-based representation and matching of 3-D objects
Authors: Jacques G. Verly, Richard L. Delanoy
Venue: ICCV
Year: 1990

A model-based technique is presented for recognizing 3-D objects using a novel object representation and a novel generic matching engine. Each object to be recognized is defined by an appearance model (AM) describing the expected appearances of the object over a range of aspects in a specific type of imagery. The AMs for all the objects to be recognized are organized in an AM hierarchy (AMH) defining object classes. This AMH, together with an image event extracted from the input imagery and primitives obtained by decomposing the event, constitute the input to the matching engine. This engine determines which object in the AMH most likely corresponds to the event and its primitives. The approach described is at the heart of an automatic target recognition system built by the authors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Feed-forward recovery of motion and structure from a sequence of 2D-lines matches
Authors: Thierry Viéville, Olivier D. Faugeras
Venue: ICCV
Year: 1990

A description is given of the development and implementation of a line segments based module of recovery of self-motion and 3-D structure. Given a monocular sequence of time-varying images and 2-D-lines matches in this sequence, the goal is to recover the camera motion and the 3-D-lines structure. A feedforward approach which combines prediction and correction is presented, and the equations are given and discussed in the case of small rigid motions. Algorithms, based on the minimization of the Mahalanobis distance between two estimates, are given and their implementations carefully discussed. The efficiency of the proposed approach is illustrated through experimental tests carried out considering noisy synthetic data and a real indoor scene.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Surface reconstruction using deformable models with interior and boundary constraints
Authors: Yuan-Fang Wang, Jih-Fang Wang
Venue: ICCV
Year: 1990

A technique is introduced for 3-D surface reconstruction and graphic animation using elastic, deformable models. The basic structure used is an imaginary elastic grid, which is made of membranous, thin-plate type material. This elastic grid is bent, twisted, compressed, and stretched into any desirable 3-D shape, or from one flexible state to another. The desired shape can be specified by the shape constraints derived automatically from images of a real 3-D object, or by an analytic surface function. Shape reconstruction is guided by a set of imaginary springs that enforce the consistency in the position, orientation, and/or curvature measurements of the elastic grid and the desired shape. The dynamics of a reconstruction process is regulated by the Hamilton principle or the principle of the least action. Implementation results using simple analytic shapes and images of real free-form objects are presented. The authors believe that their model is widely applicable in many surface reconstruction and graphic animation processes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Cooperative integration of multiple stereo algorithms
Authors: Masaki Watanabe, Yuichi Ohta
Venue: ICCV
Year: 1990

A novel scheme is proposed to integrate multiple stereo algorithms in a cooperative framework. Each algorithm is implemented in a separate module and executed in parallel. The stereo correspondence obtained in each algorithm is stored in the module. Confidence of each stereo correspondence is evaluated based on the ambiguity in the search process and it is attached to the correspondence result. During the execution, each module communicates with other modules and offers subsets of its results to another by its request. The cooperation among the modules makes it possible not only to improve the performance of each algorithm but also to make the integrated system highly adaptive to various scenes. A system integrating three stereo matching algorithms which use different kinds of image features has been developed on a parallel computer to demonstrate the feasibility of the scheme.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Direct computation of qualitative 3D shape and motion invariants
Authors: Daphna Weinshall
Venue: ICCV
Year: 1990

The author shows that the sign of the normal curvature in a given direction at a given point in the image can be computed from a simple difference of slopes of line-segments in one image. Using this result, local surface patches can be classified as convex, concave, parabolic (cylindrical), hyperbolic (saddle point) or planar. At the same time the translational component of the optical flow is obtained, from which the focus of expansion can be computed. In addition, the axes of principal curvature and the axes of zero curvature are obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
From uncertainty to visual exploration
Authors: Peter Whaite, Frank P. Ferrie
Venue: ICCV
Year: 1990

The question posed is what can be inferred from ambiguity in processes of visual interpretation? Much emphasis is naturally placed on the form of constraints used to minimize ambiguity, particularly as they pertain to such issues as perceptual acceptability. The authors feel that it is perhaps more instructive to consider what can be learned from situations where different interpretations of data are possible, i.e., the ambiguity of perception. This immediately raises a number of issues regarding the characterization of ambiguity, communicating it to other visual processes, and using ambiguity to further refine visual interpretation. The context in which the authors discuss these problems is the interpretation of scene geometry in the form of volumetric models. They describe a representation for ambiguity in terms of an ellipsoid of confidence in which there is a finite probability that the true parameters of the model can be found.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A framework for adaptive scale space tracking solutions to problems in computational vision
Authors: Gary Whitten
Venue: ICCV
Year: 1990

A unified framework is developed for efficiently solving a wide range of computational vision problems by performing adaptive scale space tracking (where a solution at a coarse resolution is tracked to solutions at ever increasing resolution). This approach is motivated by physical smoothness models, deformable sheets, based on thin elastic membranes and plates. The inherent smoothness properties of the deformable sheets act against externally applied, problem specific forces derived from images. The authors also developed the necessary relations for quantitative control of scale based parameters so that the scale space tracking process can be completely automated. Finally, they present solutions to different problems in computational vision using the framework applied to real images.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Perceptual organization of occluding contours
Authors: Lance R. Williams
Venue: ICCV
Year: 1990

The mechanics of occlusion of one surface by another are described by a set of integer linear constraints. These constraints insure that the output of a contour grouping process is physically valid and consistent with the image evidence. Among the many feasible solutions, the most compelling is the solution which best explains the presence and form of image structure. The problem of computing a complete and consistent surface boundary representation is reduced to solving an integer linear program.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A fast algorithm for active contours
Authors: Donna J. Williams, Mubarak Shah
Venue: ICCV
Year: 1990

A method of controlling snakes that combines speed, flexibility, and simplicity is presented. It is compared to the original variational calculus method of M. Kass et al. (1987) and the dynamic programming method developed by A.A. Amini et al. (1988) and found to be comparable in final results, while being faster than dynamic programming and more stable and flexible for including hard constraints than the variational calculus approach. The introduction of the concept of curvature highlights the problem of how to approximate curvature when a curve is represented by a set of discrete points. The advantages and disadvantages of a number of different approximations of curvature are pointed out.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A photometric invariant and shape constraints at parabolic points
Authors: Lawrence B. Wolff
Venue: ICCV
Year: 1990

Using rigorous methods the authors have shown that the invariant direction of isophotes at parabolic points is the projection of the principal direction of zero curvature onto the image plane. They have gone beyond considering the limited case of pure orthographic projection and have shown under what conditions this photometric invariance property breaks down and is best approximated in perspective images, and for a nondistant light source. In addition to giving experimental evidence supporting their claim about how isophotes are parallel to the direction of zero curvature at parabolic points, the authors suggest possible applications of this geometric cue to determination of orientation and curvature at parabolic points. The best advantage taken from this geometric cue is when constraint information can be obtained, knowing absolutely nothing about the reflectance map. The true power of a physical invariant is the information it gives under the most generic conditions possible, in this case any type of smooth reflectance map.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Bayesian decision theoretic approach for adaptive goal-directed sensing
Authors: Hsiang-Lung Wu, Alec Cameron
Venue: ICCV
Year: 1990

A general mathematical framework is described for applying Bayesian decision theory to selecting optimal sensing actions for achieving a given sensory goal. The information utilized in the selection process for achieving the goal includes all sensory data acquired prior to the currently considered action. This enables the selection of intelligent sensing strategies to be both adaptive and goal-directed. The authors first show how Bayesian decision theory can facilitate the selection of plans for collecting information relevant to a given task. The approach taken is quite general. It is directly applicable to multi-sensor systems. It could be used in selecting sensory actions to acquire multiple types of information at once. The use of the approach is demonstrated with an example from the domain of robot vision.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Direct estimation of deformable motion parameters from range image sequence
Authors: Masanobu Yamamoto, Pierre Boulanger, J.-Angelo Beraldin, Marc Rioux, Jacques Domey
Venue: ICCV
Year: 1990

A method is described for estimating range flow (space displacement vector field) on a nonrigid object as well as a rigid object from a sequence of range images. The method can directly estimate the deformable motion parameters by solving a system of linear equations which are obtained by substituting a linear transformation of a nonrigid object expressed by a Jacobian matrix into motion constraints based on an extension of the conventional scheme used in intensity image sequences, and the range flow is obtained from the motion parameters and linear transformation. The algorithm is supported by experiments of motion estimation of a sheet of paper, a piece of cloth, the movement of human skin, and the motion of a rubber balloon being inflated using real range image sequences acquired by a video rate range finder. Furthermore, it is shown that by adding the intensity image sequence to the range information, one can prevent the equation system from falling in an ill-posed condition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Tracking and grouping 3D line segments
Authors: Zhengyou Zhang, Olivier D. Faugeras
Venue: ICCV
Year: 1990

The authors address the motion tracking problem that arises in the context of a mobile vehicle navigating in an unknown environment where other mobile bodies such as human beings or robots may also be moving. A stereo rig mounted on the mobile vehicle provides a sequence of 3-D maps of the environment. The current stereo system is trinocular and the 3-D tokens used at the moment are line segments corresponding to significant intensity discontinuities in the images. Although the framework to solve the motion tracking problem developed in this work arises in this specific context, the authors believe it should be applicable in other contexts; in particular they could use other 3-D primitives, for example, points, combinations of points and lines, curves.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Qualitative route scene description using autonomous landmark detection
Authors: Jiang Yu Zheng, Matthew J. Barth, Saburo Tsuji
Venue: ICCV
Year: 1990

This paper introduces an approach to build a qualitative description of scenes along a route, which is used in route recognition by a mobile robot. The description consists of a series of landmarks autonomously selected by the robot from a panoramic view, which has been generated as a visual memory of scenes along routes. The basic idea to bridge the quantitative panoramic view to qualitative landmarks is to examine the 'distinctiveness' of patterns in the image and select landmarks from unique patterns that are remarkably by which to navigate.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>