OpenRaiser/Intern-Atlas huggingface dataset:
Computing optical flow from an overconstrained system of linear algebraic equations
Authors: Marco Campani, Alessandro Verri
Venue: ICCV
Year: 1990

A method is presented for the recovery of optical flow. The key idea is that the local spatial structure of optical flow, with the exception of surface boundaries, is usually rather coherent and can thus be appropriately approximated by a linear vector field. According to the proposed method, the optical flow components and their first order spatial derivatives are computed at the central points of rather large and overlapping patches which cover the image plane as the solution to a highly overconstrained system of linear algebraic equations. The equations, which are solved through the use of standard least mean square techniques, are derived from the assumptions that the changing image brightness is stationary everywhere over time and that optical flow is, locally, a linear vector field. The method has been tested on many sequences of synthetic and real images and the obtained optical flow has been used to estimate three-dimensional motion parameters with very good results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
An efficient method for multiple-circle detection
Authors: Xing Cao, Farzin Deravi
Venue: ICCV
Year: 1990

A novel approach for circle detection based on the Hough transform is presented. It avoids the use of trigonometric functions in the transform equations. Instead of using traditional circle parameterization, which involves gradient direction information, this method uses three edge points to accumulate evidence for circle centers. The method can be extended to the detection of multiple circles where the gradient direction information is only used as a guide to select candidate edge points. A set of rules is proposed for the selection of triple edge points to define circle parameters which can guarantee that the points selected will not be on different circles. The responses for different circles produced in the parameter space using the proposed method are shown to be more compact around the true centers of the circles, thus, removing the need for postprocessing in the parameter space. The application of this method not only reduces the processing time, but also avoids the detection inaccuracy caused by the edge gradient direction errors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Reconstructing 3D lines from a sequence of 2D projections: representation and estimation
Authors: Yuh-Lin Chang, Jake K. Aggarwal
Venue: ICCV
Year: 1990

The reconstruction of a 3-D line from a sequence of its 2-D projections is addressed. The authors first consider the problem of 3-D line representation and then the recursive estimation algorithm. They point out the problems with all previous 3-D line representation models, and suggest a novel approach based on simple geometrical observations. They then derive the corresponding recursive estimation algorithm for the novel representation, based on simple linear algebra. The representation model and the recursive algorithm are implemented on an IBM RT PC and simulation results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Uncertainty in interpretation of range imagery
Authors: David M. Chelberg
Venue: ICCV
Year: 1990

A description is given of a method for automatically deriving a Bayesian probability network from CAD based 3D models. This network may be used to match 3D objects to features derived from range images in the presence of uncertainty. The network describes how evidence for subparts of an object should be combined to calculate the evidence for an object. A prototype model based range interpretation system using this method is also presented. Sample results for an object are presented. For this prototype system, sources of evidence include maximum likelihood estimate fits of circular cylinders, planes, and spheres, as well as boundary data (i.e. edges).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Pose determination from line-to-plane correspondences: existence condition and closed-form solutions
Authors: Homer H. Chen
Venue: ICCV
Year: 1990

Consideration is given to a specific pose determination problem in which the sensory features are lines and the matched reference features are planes. The lines discussed are different from edge lines of an object in that they are not the intersection of boundary faces of the object. The author describes a polynomial method that, unlike previous methods, does not require prior knowledge about the location of the object. Closed-form solutions for orthogonal, coplanar, and parallel feature configurations of critical importance in real applications are derived. Basic findings concerning the necessary and sufficient conditions under which the pose determination problem can be solved are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Epicardial motion and deformation estimation from coronary artery bifurcation points
Authors: Chang Wen Chen, Thomas S. Huang
Venue: ICCV
Year: 1990

A special problem in nonrigid motion analysis, the problem of estimating the motion and deformation of the human heart, is addressed. The research has been conducted on the left ventricle 3-D data of the bifurcation points, obtained within the period of one cardiac cycle. The process of the motion analysis is divided into three phases: global motion estimation, global motion compensation, and local deformation estimation. The global motion of the left ventricle is determined using the estimated principal axes over successive time instants. Upon compensation for the global motion, the local deformation is analyzed utilizing the correspondence of individual bifurcation points over the period of the cardiac cycle via tensor analysis. Finally, in order to better understand the complex nature of the left ventricle movement, several scientific visualization techniques are exploited to view the dynamic deformation of the left ventricle surface.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Uniqueness, the minimum norm constraint, and analog networks for optical flow along contours
Authors: Atul K. Chhabra, Timothy A. Grogan
Venue: ICCV
Year: 1990

E. Hildreth's (1984) method of computing optical flow along contours cannot resolve the aperture problem for a rigidly translating straight line contour. The authors propose an additional constraint, which they call the minimum norm constraint, as a means of resolving the ambiguity for such a contour. The minimum norm constraint tends to drive the velocity estimate towards the direction normal to the contour everywhere along the contour, i.e., it counters the effect of the smoothness constraint. This is in accord with recent psychophysical studies of K. Nakayama and G. Silverman (1988) which have revealed the presence of such a tendency in the human visual system. The authors propose an analog network for computing contour based optical flow in real-time. They illustrate the minimum norm constraint through experiments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The integration of region and edge-based segmentation
Authors: Chen-Chau Chu, Jake K. Aggarwal
Venue: ICCV
Year: 1990

An algorithm is presented that integrates segmentation maps using both region and edge segmentation maps as input. The result of integration is a region map in which each region is large and compact. The operation is efficient and independent of image sources as well as segmentation techniques. The proposed algorithm allows multiple input maps and applies user-selected weights on various information sources. The scope of integration is parametrically controlled for the desired spatial resolution. A maximum likelihood estimator provides initial solutions of edge positions and strengths from multiple inputs. An iterative procedure is then used to smooth the resultant edge patterns. The edge map is converted to a region map using closed edge contours if desired. Finally, regions are merged to ensure that every region has the required properties. Experimental results are demonstrated using various segmentation techniques and real data from laser radar and thermal sensors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The dynamic analysis of apparent contours
Authors: Roberto Cipolla, Andrew Blake 0001
Venue: ICCV
Year: 1990

The authors develop previous theories of the analysis of deformation of apparent contours under viewer motion. Earlier results showing how surface curvature can be inferred from acceleration of image features are generalized for arbitrary viewer motion and perspective projection. It is shown that relative image acceleration, based on parallax measurements, is robust to uncertainties in robot motion. The theory has been implemented and extensively tested in a real-time (15 frames per second) tracking system based on deformable contours (snakes). It is shown that focusing attention by means of snakes allows rapid, robust computation of surface curvature, including discrimination of extremal and occluding contours.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Extended structure and motion analysis from monocular image sequences
Authors: Ning Cui, Juyang Weng, Paul R. Cohen
Venue: ICCV
Year: 1990

The issue of optimal motion and structure estimation from monocular image sequences with a rigidity scene is addressed. The method has the following characteristics: the dimension of the search space in the nonlinear optimization is drastically reduced by exploiting the relationship between structure and motion parameters; the degree of reliability of the observations and estimates is effectively taken into account; the proposed formulation allows arbitrary interframe motion; and the information about the structure of the scene, acquired from previous images, is systematically integrated into the new estimations. It is shown that any scale factor associated with two consecutive images in a monocular sequence is determined by the scale factor of the first two images. The simulations and experiments with long image sequences of real world scenes indicate that the optimization method developed greatly reduces the computational complexity and substantially improves the motion and structure estimation over that produced by linear algorithms.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Multiresolution image acquisition and surface reconstruction
Authors: Subhodev Das, Narendra Ahuja
Venue: ICCV
Year: 1990

Consideration is given to the problem of surface reconstruction from stereo images for large scenes having large depth ranges where it is necessary to aim cameras in different directions and to fixate at different objects. The authors concentrate on the selection of new fixation points from among the nonfixated, low resolution scene parts, and subsequent processing for surface reconstruction. The coarse stereo estimates in the vicinity of the new fixation point are refined as the images of the new fixation point gradually deblur during the process of refixation and are subsequently used to analyze the fixated parts of the scene.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Qualitative 3-D shape reconstruction using distributed aspect graph matching
Authors: Sven J. Dickinson, Alex Pentland, Azriel Rosenfeld
Venue: ICCV
Year: 1990

An approach is presented to 3-D primitive reconstruction that is independent of the selection of volumetric primitives used to model objects. The approach first takes an arbitrary set of 3-D volumetric primitives and generates a hierarchical aspect representation based on the projected surfaces of the primitives; conditional probabilities capture the ambiguity of mappings between levels of the hierarchy. The integration of object-centered and viewer-centered representations provides the indexing power of 3-D volumetric primitives, while supporting a 2-D matching paradigm for primitive reconstruction. Formulation of the problem based on grouping the image regions according to aspect is presented. No domain dependent heuristics are used; the authors exploit only the probabilities inherent in the aspect hierarchy. For a given selection of primitives, the success of the heuristic depends on the likelihood of the various aspects; best results are achieved when certain aspects are more likely, and fewer primitives project to a given aspect.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Calculating surface reflectance using a single-bounce model of mutual reflection
Authors: Mark S. Drew, Brian V. Funt
Venue: ICCV
Year: 1990

Light reflected from one surface onto a second surface changes both the intensity and spectral power distribution of light leaving the second surface. Similarly, light from the second surface illuminates the first. This mutual reflection effect can be exploited by examining pixels where interreflection is and is not present. From these measurements several intrinsic properties can be determined: the reflectance of each surface, the spectral power distribution of the incident illumination, and some constraints on the physical configuration of the two surfaces. The authors use finite dimensional linear models for the ambient illumination and for surface spectral reflectance, with m basis functions for illumination and n for surfaces. Examining p sensor values (e.g. RGB values) they find that if p satisfies the condition p>or=(2n+m)/3 they can solve for finite dimensional model descriptors of both surfaces and of the ambient illumination, as well as for a form-factor stemming from the surface configuration. With n=m=3, p can also be 3. A single-bounce model of mutual reflection accounts for the most important contribution to light intensity in an interreflecting geometry.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Robustness of correspondence-based structure from motion
Authors: Rabindranath Dutta, Mark A. Snyder
Venue: ICCV
Year: 1990

An examination is made of the robustness of correspondence-based approaches to structure from motion. It is proven in an algorithm-independent way, that small absolute errors in image displacements cause absolute errors in rotational motion parameters significant enough to lead to large relative errors in the determination of environmental depth. Even if the exact motion parameters are known a priori small errors in image displacements still lead to large errors in depth for environmental points whose distance from the camera is greater than a few multiples of the total translation in depth of the camera. In order to clarify the many robustness issues that are raised, a depth determination algorithm is developed and applied to dynamic image sequences of natural outdoor scenes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Determining back-facing curved model surfaces by analysis at the boundary
Authors: Robert B. Fisher
Venue: ICCV
Year: 1990

An examination is made of the problem of predicting when a model surface patch on a three-dimensional object is totally back-facing, and hence need not be searched for during object recognition. Examining every point on the surface patch is inelegant and impractical, yet difficulties arise with curved surface patches. The authors conclude that visibility can be determined from an analysis of the surface orientation at the patch boundary for a wide class of model surface patch types (i.e. those having constant principal curvature signs), under orthographic projection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Multiple widths yield reliable finite differences
Authors: Margaret M. Fleck
Venue: ICCV
Year: 1990

Many edge finders extract the signs of finite differences of image intensity values. Camera noise renders many of these signs unreliable. Previous algorithms for reducing noise are difficult to analyze, fail to detect faint or closely packed features, or handle restricted classes of features. The author proposes taking finite differences with a range of separations between data points, and choosing the narrowest response with statistically reliable sign. Fine detail is then detected by narrow operators. Faint features are filled in by wide operators, which can more reliably distinguish low-amplitude boundaries from noise. It is shown, both theoretically and empirically, that this method out-performs traditional Gaussian smoothing. Measurements of noise in a real camera system are also presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
BONSAI: 3D object recognition using constrained search
Authors: Patrick J. Flynn, Anil K. Jain 0001
Venue: ICCV
Year: 1990

A description is presented of BONSAI, a model-based 3-D object recognition system, which identifies and localizes 3-D objects in range images of one or more parts which have been designed on a CAD system. Recognition is performed via constrained search of the interpretation tree, using unary and binary constraints (derived automatically from the CAD models) to prune the search space. Experiments with over 200 images of 20 different parts demonstrate that the constrained search approach to 3-D object recognition has comparable accuracy to other existing systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Invariance-a new framework for vision
Authors: David A. Forsyth, Joseph L. Mundy, Andrew Zisserman, Christopher M. Brown
Venue: ICCV
Year: 1990

It is shown that curved planar objects have shape descriptors that are unaffected by the position, orientation and intrinsic parameters of the camera. These shape descriptors can be used to index quickly and efficiently into a large model base of curved planar objects, because their value is independent of pose and unaffected by perspective. Thus, recognition can proceed independent of calculating pose. Object curves are represented using conics, attached with a fitting technique that commutes with projection. This means that the pose of an object can be determined by backprojecting known conics. The authors show examples of recognition and pose determination using real image data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Steerable filters for early vision, image analysis, and wavelet decomposition
Authors: William T. Freeman, Edward H. Adelson
Venue: ICCV
Year: 1990

An efficient architecture is presented to synthesize filters of arbitrary orientations from linear combinations of basis filters, allowing one to adaptively 'steer' a filter to any orientation, and to determine analytically the filter output as a function of orientation. The authors show how to design and steer filters, and present examples of their use in several tasks: the analysis of orientation and phase, angularly adaptive filtering, edge detection, and shape-from-shading. It is also possible to build a self-similar steerable pyramid representation which may be considered to be a steerable wavelet transform. The same concepts can be generalized to the design of 3-D steerable filters, which should be useful in the analysis of image sequences and volumetric data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Collaboration between computer graphics and computer vision
Authors: André Gagalowicz
Venue: ICCV
Year: 1990

The scope concerns both applications related to computer vision such as vision for the robots of the next century and computer graphics such as audio-visuals or simulators of physical phenomena. It is a large field of new applications where refined 3-D recognition and interpretation (not yet generally solved today) will be required. The problem that the author solves more precisely is to understand and recognize a 3-D scene observed by two cameras in a stereo position, using a given model of the scene.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Similarity extraction and modeling
Authors: Luc Van Gool, Johan Wagemans, Johan Vandeneede, André Oosterlinck
Venue: ICCV
Year: 1990

Human subjects easily perceive and extensively use shape regularities such as symmetry or periodicity when they are confronted with tile task of object description and recognition. A computer vision algorithm is presented that emulates such behavior in that it similarly makes use of shape redundancies for the concise description and meaningful segmentation of planar object contours. The contours are analyzed in so-called arc length space. This parameter space facilitates the detection of regularities under a broad range of viewing conditions. Several of the irregularities which have traditionally been treated in isolation, are given a unified substrate for their detection and use in building compact models. Regularity consistency checks are made and, if necessary, altered versions are inferred.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A computational model for face location
Authors: Venu Govindaraju, Sargur N. Srihari, David B. Sher
Venue: ICCV
Year: 1990

The authors adopted a model-based approach, where the shape of the object is defined in terms of several mini-templates. The mini-templates are abstract descriptions of simple geometric features like arcs and corners. Relationships between mini-templates are not rigid. Rather, they are represented by springs that allow deformation of a template in terms of its size and orientation. Cost functionals are determined empirically. The authors expect their system to generate candidate regions in a given photograph associated with a rank of its goodness.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
On the sensitivity of geometric hashing
Authors: W. Eric L. Grimson, Daniel P. Huttenlocher
Venue: ICCV
Year: 1990

A formal model is presented for analyzing how the method performs in the presence of sensory uncertainty. The method performs well for simple images or for exact data. However, the performance degrades rapidly for cluttered scenes or in the presence of even moderate sensor error (3-5 pixels).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Robust curve detection by temporal geodesics
Authors: Dan Gutfinger, R. Nishimura, H. Doi, Jack Sklansky
Venue: ICCV
Year: 1990

The formation of temporal geodesics (i.e., fast routes) in a velocity field seems to offer a means of detecting curves by parallel hardware in a wide range of images with little prior design information. This hypothesis was tested by devising and constructing a dotted-curve detector based on it, and applying the detector to several synthetic dotted images covering a wide range of dotted curves and dotted partially coherent noise. The results are encouraging. The dotted-curve detector searches for fast routes in a velocity field determined locally by the approximate collinearity or cocircularity of clusters of dots, and globally by the tortuousness of the route and the uniformity of the spacing of dots along the route. The routes are found by a parallel adaptive classification of the dots into curve dots and noise dots, followed by a parallel merging and splitting of graphs spanning temporal close dots or subgraphs at successively higher levels of abstraction.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>