OpenRaiser/Intern-Atlas huggingface dataset:
Recognition of Human Body Motion Using Phase Space Constraints
Authors: Lee W. Campbell, Aaron F. Bobick
Venue: ICCV
Year: 1995

A new method for representing and recognizing human body movements is presented. The basic idea is to identify sets of constraints that are diagnostic of a movement: expressed using body-centered coordinates such as joint angles and in force only during a particular movement. Assuming the availability of Cartesian tracking data, we develop techniques for a representation of movements defined by space curves in subspaces of a "phase space." The phase space has axes of joint angles and torso location and attitude, and the axes of the subspaces are subsets of the axes of the phase space. Using this representation we develop a system for learning new movements from ground truth data by searching for constraints. We then use the learned representation for recognizing movements in unsegmented data. We train and test the system on nine fundamental steps from classical ballet performed by two dancers; the system accurately recognizes the movements in the unsegmented stream of motion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Geodesic Active Contours
Authors: Vicent Caselles, Ron Kimmel, Guillermo Sapiro
Venue: ICCV
Year: 1995

A novel scheme for the detection of object boundaries is presented. The technique is based on active contours deforming according to intrinsic geometric measures of the image. The evolving contours naturally split and merge, allowing the simultaneous detection of several objects and both interior and exterior boundaries. The proposed approach is based on the relation between active contours and the computation of geodesics or minimal distance curves. The minimal distance curve lays in a Riemannian space whose metric as defined by the image content. This geodesic approach for object segmentation allows to connect classical "snakes" based on energy minimization and geometric active contours based on the theory of curve evolution. Previous models of geometric active contours are improved as showed by a number of examples. Formal results concerning existence, uniqueness, stability, and correctness of the evolution are presented as well.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
On Multi-Feature Integration for Deformable Boundary Finding
Authors: Amit Chakraborty, Marcel Worring, James S. Duncan
Venue: ICCV
Year: 1995

Precise segmentation of underlying objects in an image is very important especially for biomedical image analysis. We present an integrated approach for boundary finding using region and curvature information along with the gradient. Unlike the previous methods, where smoothing is enforced by penalizing curvature, here the grey level curvature is used as an extra source of information. However, information fusion may not be useful unless used properly. To address that, we present results that highlight the pros and cons of using the various sources of information and indicate when one should get precedence over the others.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Face Detection by Fuzzy Pattern Matching
Authors: Qian Chen 0001, Haiyuan Wu, Masahiko Yachida
Venue: ICCV
Year: 1995

The paper describes an approach to detect faces whose size and position are unknown in an image with a complex background. The candidates of faces are detected by finding out "face like" regions in the input image using the fuzzy pattern matching method. The perceptually uniform color space is used in our research in order to obtain reliable results. The skin color that is used to detect face like regions, is represented by a model developed by us called skin color distribution function. The skin color regions are then extracted by estimating a measure that describes how well the color of a pixel looks like the skin color for each pixel in the input image. The faces which appear in images are modeled as several 2 dimensional patterns. The face like regions are extracted by a fuzzy pattern matching approach using these face models. The face candidates are then verified by estimating how well the extracted facial features fit a face model which describes the geometrical relations among facial features.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Model of Figure-Ground Segregation from Kinetic Occlusion
Authors: George T. Chou
Venue: ICCV
Year: 1995

The paper presents a model of image segmentation that can distinguish foreground from background purely on the basis of motion information. The main processing steps involved are: detection of motion boundaries, and analysis of figure ground relationship. The proposed model utilizes the observation that in kinetic occlusion, motion boundaries typically display mixture motion information, and foreground surfaces tend to move with motion boundaries. Through distributed probabilistic modeling, these constraints can be embedded into computations with efficient network representations. The resulting networks use spatiotemporal Gabor filters as front ends, and are suitable for parallel distributed processing. We demonstrate the application of the model in the decomposition of moving images into surfaces according to depth.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Motion from the Frontier of Curved Surfaces
Authors: Roberto Cipolla, Kalle Åström, Peter J. Giblin
Venue: ICCV
Year: 1995

The frontier of a curved surface is the envelope of contour generators showing the boundary, at least locally, of the visible region swept out under viewer motion. In general, the outlines of curved surfaces (apparent contours) from different viewpoints are generated by different contour generators on the surface and hence do not provide a constraint on viewer motion. We show that frontier points, however, have projections which correspond to a real point on the surface and can be used to constrain viewer motion by the epipolar constraint. We show how to recover viewer motion from frontier points for both continuous and discrete motion, calibrated and uncalibrated cameras. We present preliminary results of an iterative scheme to recover the epipolar line structure from real image sequences using only the outlines of curved surfaces. A statistical evaluation as also performed to estimate the stability of the solution.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Surface Geometry from Cusps of Apparent Contours
Authors: Roberto Cipolla, Gordon J. Fletcher, Peter J. Giblin
Venue: ICCV
Year: 1995

It is known that the deformations of the apparent contours of a surface under perspective projection and viewer motion enable the recovery of the geometry of the surface, for example by utilising the epipolar parametrization. These methods break down with apparent contours that are singular i.e. with cusps. In this paper, we study this situation in detail and show how, nevertheless, the surface geometry (including the Gauss curvature and mean curvature of the surface) can be recovered by following the cusps. Indeed the formulae are much simpler in this case, and require lower spatio-temporal derivatives than in the general case of nonsingular apparent contours. We give a simulated example, and also show that following cusps does not by itself provide us with information on ego-motion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Improving Laser Triangulation Sensors Using Polarization
Authors: James Clark 0001, Emanuele Trucco, H.-F. Cheung
Venue: ICCV
Year: 1995

We report a novel application of polarization based vision addressing the robustness of laser triangulation range sensors. Such sensors are based on the accurate detection of a pattern of laser light projected onto a scene, usually a point or line. Typical problems arise with highly specularly reflective surfaces, which can generate visible reflections of the light in various parts of the image. This can confuse the detection algorithms and lead to wrong range measurements. This paper demonstrates experimentally the feasibility of polarization based vision for disambiguating multiple specular inter reflections of the laser light. We concentrate on metal components as they have high interest for inspection in manufacturing, and show positive results with situations of various complexities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Learning-Based Hand Sign Recognition Using SHOSLIF-M
Authors: Yuntao Cui, Daniel L. Swets, Juyang Weng
Venue: ICCV
Year: 1995

We present a self-organizing framework called the SHOSLIF-M for learning and recognizing spatiotemporal events (or patterns) from intensity image sequences. The proposed framework consists of a multiclass, multivariate discriminant analysis to automatically select the most discriminating features (MDF), a space partition tree to achieve a logarithmic retrieval time complexity for a database of n items, and a general interpolation scheme to do view inference and generalization in the MDF space based on a small number of training samples. The system is tested to recognize 28 different hand signs. The experimental results show that the learned system can achieve a 96% recognition rate for test sequences that have not been used in the training phase.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Adaptive Shape Evolution Using Blending
Authors: Douglas DeCarlo, Dimitris N. Metaxas
Venue: ICCV
Year: 1995

We propose a shape representation scheme which allows two shapes to be combined into a single model. The desired regions of the two shapes are selected, and then merged together forming a blended shape. For reconstruction, blending is incorporated into a deformable model framework. The model automatically adapts to the data, blending when necessary. Hierarchical blending allows multiple blends of a shape to occur forming an evolution from the initial shape of a sphere to the final shape. Blending also allows the insertion of a hole between arbitrary locations. The models used are globally defined, making the recovered shape a natural symbolic description. We present reconstruction experiments involving shapes of various topologies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Real-Time X-Ray Inspection of 3D Defects in Circuit Board Patterns
Authors: Hideaki Doi, Yoko Suzuki, Yasuhiko Hara, Tadashi Iida, Yasuhiro Fujishita, Koichi Karasaki
Venue: ICCV
Year: 1995

The paper reports defect detection techniques using X-rays in order to find three dimensional defects such as funnels in printed circuit board (PCB) patterns. X-ray images of fine PCB patterns, however, show patterns on more than one layer, having degrees of distortion that vary over an image, are subject to intensity variation due to fluctuations in the intensity of the X-ray source, and so on. To overcome these problems, we examined distortion caused by perspective transforms on the sphere surface of an X-ray detector and developed a defect detection algorithm based on feature extraction. Fluctuation of X-ray strength and heavy shading of the acquired image are compensated by signal processing. Evaluation of the system confirmed that the system could detect defects deeper than 20 /spl mu/m and with surface areas greater than 70/spl times/35 /spl mu/m/sup 2/ in fine PCB patterns and that the inspection time for a 600/spl times/800 mm/sup 2/ PCB was only 20 minutes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
COSMOS-A Representation Scheme for Free-Form Surfaces
Authors: Chitra Dorai, Anil K. Jain 0001
Venue: ICCV
Year: 1995

We address the problem of representing and recognizing arbitrarily curved 3D rigid objects when: the objects may vary in shape and complexity, and no restrictive assumptions are made about the types of surfaces on the object. We propose a new and general surface representation scheme for recognizing objects with free form (sculpted) surfaces from range data. In this scheme, an object is described concisely in terms of maximal surface patches of constant shape index. These maximal patches are mapped onto the unit sphere via their orientations, and aggregated via shape spectral functions. Properties such as surface area, curvedness and connectivity that capture local and global information are also built into the representation. The scheme yields not only a meaningful and rich surface description useful for the recoverability of the object, but also a set of powerful indexing primitives for object matching. We demonstrate the generality and the effectiveness of our scheme using real range images of complex objects. We also present results on the categorization of object views based on a novel shape spectral matching technique.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Indexing Visual Representations through the Complexity Map
Authors: Benoit Dubuc, Steven W. Zucker
Venue: ICCV
Year: 1995

In differential geometry curves are characterized as mappings from an interval to the plane. In topology curves are characterized as a Hausdorff space with certain countability properties. Neither of these definitions captures the role that curves play in vision, however, in which curves can denote simple objects (such as a straight line), or complicated objects (such as a jumble of string). The difference between these situations is in part a measure of their complexity, and in part a measure of their dimensionality. Note that the map defining such curves is unknown, as is the proper way to represent them. We propose a formal complexity theory of curves appropriate for computational vision in general, and for problems like separating straight lines from jumbles in particular. The theory is applied to the problem of perceptual grouping.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Transfer of Fixation for an Active Stereo Platform via Affine Structure Recovery
Authors: Stuart M. Fairley, Ian D. Reid 0001, David William Murray 0001
Venue: ICCV
Year: 1995

This paper describes an algorithm for stereo tracking using 3D affine transfer of a body-centred fixation point. Transfer is based on corners detected in the image and matched over time and in stereo. The paper presents a method of basing the transfer on all the available data, providing immunity to noise and poor conditioning. The paper also shows an implementation at video rates on a four axis active camera platform. Graceful degradation in the presence of insufficient data and fixed latency tracking in parallel with the structure calculation provide robust performance. Recovered trajectories are shown in an approximately Euclidean frame while structure transfer is demonstrated by the evolution of the target's convex hull.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Global Rigidity Constraints in Image Displacement Fields
Authors: Cornelia Fermüller, Yiannis Aloimonos
Venue: ICCV
Year: 1995

Image displacement fields-optical flow fields, stereo disparity fields, normal flow fields-due to rigid motion possess a global geometric structure which is independent of the scene in view. Motion vectors of certain lengths and directions are constrained to lie on the imaging surface at particular loci whose location and form depends solely on the 3D motion parameters. If optical flow fields or stereo disparity fields are considered, then equal vectors are shown to lie on conic sections. Similarly, for normal motion fields, equal vectors lie within regions whose boundaries also constitute conics. By studying various properties of these curves and regions and their relationships, a characterization of the structure of rigid motion fields is given. The goal of this paper is to introduce a concept underlying the global structure of image displacement fields. This concept gives rise to various constraints that could form the basis of algorithms for the recovery of visual information from multiple views.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Color Constancy under Varying Illumination
Authors: Graham D. Finlayson, Brian V. Funt, Kobus Barnard
Venue: ICCV
Year: 1995

Illumination is rarely constant in intensity or color throughout a scene. Multiple light sources with different spectra-sun and sky, direct and interreflected light-are the norm. Nonetheless, almost all color constancy algorithms assume that the spectrum of the incident illumination remains constant across the scene. We assume the converse, that illumination does vary, in developing a new algorithm for color constancy. Rather than creating difficulties, varying illumination is in fact a very powerful constraint. Indeed tests of our algorithm using real images of an office scene show excellent results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Bayesian Decision Theory, the Maximum Local Mass Estimate, and Color Constancy
Authors: William T. Freeman, David H. Brainard
Venue: ICCV
Year: 1995

Vision algorithms are often developed in a Bayesian framework. Two estimators are commonly used: maximum a posteriori (MAP), and minimum mean squared error (MMSE). We argue that neither is appropriate for perception problems. The MAP estimator makes insufficient use of structure in the posterior probability. The squared error penalty of the MMSE estimator does not reflect typical penalties. We describe a new estimator, which we call maximum local mass (MLM) [10, 26, 65], which integrates the local probability density. The MLM method is sensitive to local structure of the posterior probability, which MAP is not. The new method uses an optimality criterion that is appropriate for perception tasks: it finds the most probable approximately correct answer. For the case of low observation noise, we provide an efficient approximation. We apply this new estimator to color constancy. An unknown illuminant falls on surfaces of unknown colors. We seek to estimate both the illuminant spectrum and the surface spectra from photosensor responses which depend on the product of the unknown spectra. In simulations, we show that the MLM method performs better than the MAP estimator, and better than two standard color constancy algorithms. The MLM method may prove useful in other vision problems as well.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Polymorphic Grouping for Image Segmentation
Authors: Claudia Fuchs, Wolfgang Förstner
Venue: ICCV
Year: 1995

The paper describes a new approach to image segmentation. It accepts the inherent deficiencies occuring when extracting low-level features and when dealing with the complexity of real scenes. Image segmentation therefore is understood as deriving a rich symbolic description useful for tasks such as stereo or object recognition in outdoor scenes. The approach is based on a polymorphic scheme for simultaneously extracting points, lines and segments in a topologically consistent manner, together with their mutual relations derived from the feature adjacency graph (FAG) thereby performing several grouping steps which gradually use more and more specific domain knowledge to achieve an optimal image description. The heart of the approach is (1) a detailed analysis of the FAG and (2) a robust estimation for validating the found geometric hypotheses. The analysis of the FAG, derived from the exoskeleton of the features, allows to detect inconsistencies of the extracted features with the ideal image model, a cell-complex. The FAG is used for finding hypotheses about incidence relations and geometric hypotheses, such as collinearity or parallelity, also between non-neighbored points and lines. The M-type robust estimation is used for simultaneously eliminating wrong hypotheses on geometric relationships. It uses a new argument for the weighting function.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Combining Color and Geometry for the Active, Visual Recognition of Shadows
Authors: Gareth Funka-Lea, Ruzena Bajcsy
Venue: ICCV
Year: 1995

Shadows are a frequent occurrence, but they cannot be infallibly recognized until a scene's geometry and lighting are known. We present a number of cues which together strongly suggest the identification of a shadow and which can be examined with low cost. The techniques are: a color image segmentation method that recovers single material surfaces as single image regions irregardless of the surface partially in shadow, a method to recover the penumbra and umbra of shadow; a method for determining whether some object could be obstructing a light source. The last cue requires the examination of well understood shadows in the scene. Our observer is equipped with an extendable probe for casting its own shadows. Actively obtained shadows allow the observer to experimentally determine the location of the light sources in the scene. The system has been tested both indoors and out.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Surface Orientation and Curvature from Differential Texture Distortion
Authors: Jonas Gårding
Venue: ICCV
Year: 1995

A unified differential geometric framework for estimation of local surface shape and orientation from projective texture distortion is proposed, based on a differential version of the texture stationarity assumption introduced by Malik and Rosenholtz. This framework allows the information content of the gradient of any texture descriptor defined in a local coordinate frame to be characterized in a very compact form. The analysis encompasses both full affine texture descriptors and the classical "texture gradients". For estimation of local surface orientation and curvature from uncertain observations of affine texture distortion, the proposed framework allows the dimensionality of the search space to be reduced from five to one.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Optical Flow and Deformable Objects
Authors: Andrea Giachetti 0001, Vincent Torre
Venue: ICCV
Year: 1995

When a plane undergoes a deformation that can be represented by a planar linear vector field, the projected vector field on the image plane of an optical device is at most quadratic. This 2D motion field has one singular point, with eigenvalues identical to those of the singular point describing the deformation. As a consequence, the nature of the singular point of the deformation is a projective invariant. When the plane moves and experiences a linear deformation at the same time, the associated 2D motion field is still quadratic with at most 3 singular points. In the case of a normal rototranslation, i.e. when the angular velocity is normal to the plane, and of a linear deformation, the 2D motion field has at most one singular point and substantial information on the rigid motion and on the deformation can be recovered from it. Experiments with simulated deformations and real deformable objects show that the proposed analysis can provide accurate results and information on more general 3D deformations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>