OpenRaiser/Intern-Atlas huggingface dataset:
Compact image representation from multiscale edges
Authors: Sifen Zhong, Stéphane Mallat
Venue: ICCV
Year: 1990

The edges of an image can be detected at different scales from the local maxima of its wavelet transform. an algorithm is described that reconstructs images from their edges at dyadic scales. The wavelet maxima representation is a novel reorganization of the image information that makes it possible to develop algorithms uniquely based on edges for solving image processing and computer vision problems. The evolution of the wavelet maxima across scales gives a precise characterization of the edge type which can be used for pattern recognition. A coding algorithm is described that selects the most important image edges in order to obtain a compact representation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A system for automatic vectorization and interpretation of map-drawings
Authors: Sergey Ablameyko 0001, Vladimir Bereishik, Oleg Frantskevich, Maria Homenko, E. Melnik, Oleg Okun, Nadeshda Paramonova
Venue: ICCV
Year: 1993

The authors describe a system for automatic interpretation of map-drawings. To vectorize large-size 2-D line-drawing images, an effective pipeline-oriented scheme and special techniques have been developed on the basis of economic image representation. This allows processing large-size binary images on a personal computer and obtaining satisfactory time characteristics. This approach can be easily realized in a pipelined architecture using a simple transputer chain. The document object recognition techniques are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Discrete models for energy-minimizing segmentation
Authors: Andrew Ackah-Miezan, André Gagalowicz
Venue: ICCV
Year: 1993

The image segmentation problem may be considered as the search for a way to subdivide an image domain into regions which represent the projection of visible parts of objects in a real scene. The authors analyze the problem of image segmentation in the framework of the approximation theory as defined by D. Mumford and J. Shah (1988). They show that for real images the problem of the choice of the energy functional is dictated by the model of the world, and they propose a method to optimize it based on a deterministic algorithm processed at multiple levels of resolution. Problems encountered in dealing with real scenes lead to several modifications of the algorithm and the energy functional. Images are shown on which the algorithm was tested.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Fast and robust 3D recognition by alignment
Authors: Tao Daniel Alter, W. Eric L. Grimson
Venue: ICCV
Year: 1993

Alignment is a common approach for recognizing 3-D objects in 2-D images. Current implementations handle image uncertainty in ad hoc ways. These errors, however, can propagate and magnify through the alignment computations, such that the ad hoc approaches may not work. The authors give a technique for tightly bounding the propagated error, which can be used to make the recognition robust while still being efficient. Previous analyses of alignment have demonstrated a sensitivity to false positives. But these analyses applied only to point features, whereas alignment systems often rely on extended features for verifying the presence of a model in the image. A new formula is derived for the selectivity of a line feature. It is experimentally demonstrated using the technique for computing error bounds that the use of line segments significantly reduces the expected false positive rate. The extent of the improvement is that an alignment system that correctly handles propagated error is expected to remain reliable even in substantially cluttered scenes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Optical flow from 1D correlation: Application to a simple time-to-crash detector
Authors: Nicola Ancona, Tomaso A. Poggio
Venue: ICCV
Year: 1993

The authors show that a new technique exploiting 1-D correlation of 2-D or even 1-D patches between successive frames may be sufficient to compute a satisfactory estimation of the optical flow field. The algorithm is well-suited to VLSI implementation. The sparse measurements provided by the technique can be used to compute qualitative properties of the flow for a number of different visual tasks. In particular, a method is described to combine the 1-D correlation technique with a scheme for detecting expansion or rotation (T. Poggio et al., 1991) in a simple algorithm which also suggests interesting biological implications. The algorithm provides a rough estimate of time-to-crash. It was tested on real image sequences. Its performance is discussed and the results are compared to previous approaches.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Mathematical morphology: The Hamilton-Jacobi connection
Authors: Alan B. Arehart, Luc Vincent, Benjamin B. Kimia
Venue: ICCV
Year: 1993

The authors complement the standard algebraic view of mathematical morphology with a geometric, differential view. Three observations underlie this approach. (1) Certain structuring elements (convex) are scalable in that a sequence of repeated operations is equivalent to a single operation, but with a larger structuring element of the same shape. (2) To determine the outcome of the operation, it is sufficient to consider how the boundary is modified. (3) The modifications of the boundary are such that each point can be moved along the normal by a certain amount, which is dependent on the structuring element. Taken together, these observations, when the size of the structuring element shrinks to zero, assert that mathematical morphology operations with a convex structuring element are captured by a differential deformation of the boundary along the normal, governed by a Hamilton-Jacobi partial differential equation (PDE). A second theme is to show that mathematical morphology operations can be numerically implemented in a highly accurate fashion as the solution of these PDEs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Visual echo analysis
Authors: Esfandiar Bandari, James J. Little
Venue: ICCV
Year: 1993

The term visual echoes is introduced as a common framework for the analysis of multi-frame optical flow, binocular and trinocular stereo, stationary texture and boundary symmetries. The authors examined cepstral filtering, a powerful nonlinear adaptive technique for the retrieval of echoes, as a common methodology to address these visual routines. They consider the application of cepstral analysis to computational vision, review improvements to traditional methods, and provide a comparison with other routines presently used. A general multievidential correlation approach is introduced which lends itself to several computational techniques. CepsCorr, it is called, is a simple general technique that can accept different matching routines as its measurement kernel. The evidence provided by each iteration of cepsCorr can then be combined to provide a more accurate estimate of motion or binocular disparity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Localization using combinations of model views
Authors: Ronen Basri, Ehud Rivlin
Venue: ICCV
Year: 1993

A method for localization, the act of recognizing the environment, is presented. The method is based on representing the scene as a set of 2-D views and predicting the appearances of novel views by linear combinations of the model views. The method accurately approximates the appearance of scenes under weak perspective projection. Analysis of this projection as well as experimental results demonstrate that in many cases this approximation is sufficient to accurately describe the scene. When weak perspective approximation is invalid, either a larger number of models can be acquired or an iterative solution to account for the perspective distortions can be used. The method has several advantages over other approaches. It uses relatively rich representations; the representations are 2-D rather than 3-D; and localization can be done from only a single 2-D view.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Multiple knowledge sources and evidential reasoning for shape recognition
Authors: Bernard Besserer, Stéphane Estable, B. Ulmer
Venue: ICCV
Year: 1993

A shape recognition approach is presented. Uncertainty handling, combining, and propagation form the heart of the method. Multiple knowledge sources extract information from the segmented image and increase knowledge about undefined shapes. Knowledge sources have to be tuned to discriminate shape classes, and a critical number of independent knowledge sources guarantees the classification. Information provided by the knowledge sources is stored in the Shafer form of probability mass assignment. Dempster's rule is used to update belief in classes. A brief theoretical overview is given. Combined with a heuristic, this method achieves interesting results as well as a short execution time. An example derived from an application in the PROMETHEUS project, consisting of traffic sign recognition on a motorway, illustrates this method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Looking for trouble: Using causal semantics to direct focus of attention
Authors: Lawrence Birnbaum, Matthew Brand, Paul R. Cooper
Venue: ICCV
Year: 1993

Vision should provide an explanation of the scene in terms of a causal semantics. The authors propose a characterization of what constitutes visual understanding. The cornerstone of the proposal is that visual understanding is fundamentally a matter of developing a causal explanation of the scene, i.e., of determining the causal significance of the elements in a scene, and the causal relationships among those elements. Simple, naive physical knowledge is used as the basis of a vertically integrated vision system that explains arbitrarily complex stacked block structures. The semantics provides a basis for controlling the application of visual attention, and forms a framework for the explanation that is generated. It is shown that the program sequentially explores scenes of complex blocks structures, identifies functional substructures such as arches and cantilevers, and develops an explanation of why the whole construction stands and the role of each block in its stability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A framework for the robust estimation of optical flow
Authors: Michael J. Black, P. Anandan 0001
Venue: ICCV
Year: 1993

The authors consider the problem of robustly estimating optical flow from a pair of images using a new framework based on robust estimation which addresses violations of the brightness constancy and spatial smoothness assumptions. They also show the relationship between the robust estimation framework and line-process approaches for coping with spatial discontinuities. In doing so, the notion of a line process is generalized to that of an outlier process that can account for violations in both the brightness and smoothness assumptions. A graduated non-convexity algorithm is presented for recovering optical flow and motion discontinuities. The performance of the robust formulation is demonstrated on both synthetic data and natural images.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A design for a visual motion transducer
Authors: Andrew Blake 0001, Gabriel Hamid, Lionel Tarassenko
Venue: ICCV
Year: 1993

A design that builds on well-known schemes using gratings is outlined. The key development here is the use of commutation as a means of modulating the grating output signal. This enables backwards and forwards motion to be distinguished. Results from an analog implementation of the visual motion transducer are presented. The current transducer measures translational motion across the grating. The design is also shown to be capable of extension to direct measurement of the divergence and curl of the flow field.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Grasping visual symmetry
Authors: Andrew Blake 0001, Michael J. Taylor 0001, Adrian Cox
Venue: ICCV
Year: 1993

The authors discuss establishing a relationship between symmetry and two-fingered grasping of planar contours. Visual representations are chosen to meet the requirements of specified tasks such as object recognition or stereoscopic matching. When vision is regarded as a haptic sense, a new operational description is called for in support of dextrous manipulation. In the context of two-fingered grasp, an appropriate description can be constructed in terms of local reflectional and rotational symmetry. Related to symmetry-based representatons that have been used in pattern and object recognition, its structure is determined not heuristically, but precisely, by the nature of the grasping task. Its value is demonstrated by its incorporation into the control of a robot that can manipulate objects under visual guidance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Texture discrimination by local generalized symmetry
Authors: Yoram Bonneh, Daniel Reisfeld, Yehezkel Yeshurun
Venue: ICCV
Year: 1993

Texture consists of local variance of gray level or edge intensity values. The authors have recently presented a generalized symmetry operator that captures local spatial relations of image patterns. They show that activity differences in the continuous intensity map produced by the local generalized symmetry operator can be efficiently used to detect texture boundaries. Using almost all available quantitative results of human performance in artificial texture discrimination, the authors show that the algorithm favorably compares with other computational approaches. Stressing the necessity of benchmarks for computer vision algorithms, the authors also discuss an exhaustive set of textures that could be used as experimental stimuli for both humans and machines. The performance of the algorithm is demonstrated on some of these artificial textures as well as on natural images.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Projectively invariant decomposition and recognition of planar shapes
Authors: Stefan Carlsson
Venue: ICCV
Year: 1993

An algorithm is presented for computing a decomposition of planar shapes into convex subparts represented by ellipses. The method is invariant to projective transformations of the shape, and thus the ellipses can be used for matching and definition of invariants in the same way as points and lines. The method works for arbitrary planar shapes admitting at least four distinct tangents and is based on finding ellipses with four points of contact to the given shape. The cross ratio computed from the four points on the ellipse can then be used as a projectively invariant index. For a given shape, each pair of ellipses can be used to compute two independent projective invariants. The set of invariants computed for each ellipse pair can be used as indexes to a hash table from which a model hypothesis can be generated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Vision-based construction of CAD models from range images
Authors: Xin Chen, Francis Schmitt 0001
Venue: ICCV
Year: 1993

The authors propose an edge-based method for the automatic construction of CAD models from range images of a prototype object. First, surface discontinuities of C/sup 0/ and C/sup 1/ types and the curves of surface curvature extrema are extracted from the range images. Then, a piecewise G/sup 1/-continuous surface description with triangular Gregory-Be/spl acute/zier patches is constructed to embed these extracted surface characteristics. The construction of this description is adaptive in the sense that an initially rough approximation is progressively refined at the locations where the approximation accuracy does not meet the requirements.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Robust vergence with concurrent detection of occlusion and specular highlights
Authors: Wee-Soon Ching, Peng-Seng Toh, Kap-Luk Chan, Meng Hwa Er
Venue: ICCV
Year: 1993

The authors describe an exploratory vergence method which has the ability to detect occlusion and specular highlights using information that is inherent in the vergence process. They propose an active exploratory vergence method based on concurrent cross-correlation of multi-scale stereo images. This method is capable of detecting occlusion and specular highlights concurrently during the vergence process. It not only improves computational efficiency but also leads to the exploration of a better viewing direction and position that overcome the problem created by occlusion and specular highlights. An efficient parallel implementation of the multi-scale cross-correlation algorithm is also described. The robustness of the proposed method against occlusion and specular highlights is demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Building and using flexible models incorporating grey-level information
Authors: Timothy F. Cootes, Christopher J. Taylor 0001, Andreas Lanitis, David H. Cooper, Jim Graham
Venue: ICCV
Year: 1993

The authors describe a technique for building compact models of the shape and appearance of flexible objects seen in 2-D images. The models are derived from the statistics of sets of labeled images of example objects. Each model consists of a flexible shape template, describing how important points of the object can vary, and a statistical model of the expected grey levels in regions around each model point. Such models have proved useful in a wide variety of applications. A description is given on how the models can be used in local image search, and examples of their application are included.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Dynamic calibration of an active stereo head
Authors: James L. Crowley, Philippe Bobet, Cordelia Schmid
Venue: ICCV
Year: 1993

The authors present a method for using objects in a scene to define the reference frame for 3-D reconstruction. They first present a simple technique to calibrate an orthographic projection from four non-coplanar reference points. It is then shown that the observation of two additional known scene points can provide the complete perspective projection. When used with a known object, this technique permits a calibration of the full projective transformation matrix. For an arbitrary non-coplanar set of four points, this calibration provides an affine basis for the reconstruction of local scene structure. When the four points define three orthogonal vectors, the basis is orthogonal, with a metric defined by the lengths of the three vectors. This technique is demonstrated for the case of a cube. Results are presented in which five and a half points on the cube are sufficient to compute the projective transformation for an orthogonal basis by direct observation without matrix inversion. Experiments are outlined for reducing the imprecision due to pixel quantization and noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A spherical representation for the recognition of curved objects
Authors: Herve Delingette, Martial Hebert, Katsushi Ikeuchi
Venue: ICCV
Year: 1993

The authors introduce a surface representation for recognizing curved objects. The approach begins by representing an object by a discrete mesh of points built from range data or from a geometric model of the object. The mesh is computed from the data by deforming a standard shaped mesh, for example, an ellipsoid, until it fits the surface of the object. Local regularity constraints that the mesh must satisfy are defined. A canonical mapping is then defined between the mesh describing the object and a standard spherical mesh. A surface curvature index which is pose-invariant is stored at every node of the mesh. This object representation is used for recognition by comparing the spherical model of a reference object with the model extracted from a new observed scene. It is shown that the similarity between reference model and observed data can be evaluated, and it is also demonstrated that the pose of the reference object in the observed scene can be easily computed using this representation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Quantitative analysis of the viewpoint consistency constraint in model-based vision
Authors: Li Du, Geoffrey D. Sullivan, Keith D. Baker
Venue: ICCV
Year: 1993

The authors present a quantitative analysis of the viewpoint consistency constraint (VCC), which is the fundamental principle behind model-based methods for recognizing 3-D objects from 2-D data. It defines a measure of viewpoint consistency error (VCE), based on a formal model of image feature errors. Existing methods for establishing feature correspondences using the VCC are discussed. The poor performance of incremental methods is demonstrated and attributed to the failure to ensure that global consistency improves during search. A more reliable method, viewpoint consistency ascent, which uses the VCE explicitly as a heuristic for a state-space search, is presented. The two algorithms are compared in an experimental study. The approach to quantitative analysis of alternative algorithms is illustrated, which may be applied to model based object recognition more generally.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Egomotion analysis based on the Frenet-Serret motion model
Authors: Zoran Duric, Azriel Rosenfeld, Larry S. Davis
Venue: ICCV
Year: 1993

A new model, Frenet-Serret motion, is proposed for the motion of an observer in a stationary environment. This model relates the motion parameters of the observer to the curvature and torsion of the path along which the observer moves. Screw-motion equations for Frenet-Serret motion are derived and employed for geometrical analysis of the motion. Normal flow is used to derive constraints on the rotational and translational velocity of the observer and to compute egomotion by intersecting these constraints in the manner proposed by Z. Duric/spl acute/ and Y. Aloimonos (1989). The accuracy of egomotion estimation is analyzed for different combinations of observer motion and feature distance. The authors explain the advantages of controlling feature distance to analyze egomotion and derive the constraints on depth which make either rotation or translation dominant in the perceived normal flow field. The results of experiments on real image sequences are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>