OpenRaiser/Intern-Atlas huggingface dataset:
Automatic Recognition of Human Facial Expressions
Authors: Katsuhiro Matsuno, Chil-Woo Lee, Satoshi Kimura, Saburo Tsuji
Venue: ICCV
Year: 1995

The paper presents a new idea for detecting an unknown human face in input imagery and recognizing his/her facial expression represented in the deformation of the two dimensional net, called potential net. The method deals with the facial information, faceness and expressions, as an overall pattern of the net activated by edges in a single input image of face, rather than from changes in the shape of the facial organs or their geometrical relationships. We build models of facial expressions from the deformation patterns in the potential net for face images in the training set of different expressions and then project them into emotion space. Expression of an unknown subject can be recognized from the projection of the net for the image into the emotion space. The potential net is further used to model the common human face. The mosaic method representing energy in the net is used as a template for finding candidates for the face area and the candidates are verified their faceness by projecting them into emotion space in order to select the finalist. Precise location of the face is determined by the histogram analysis of vertical and horizontal projections of edges.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Recursive Filter for Phase Velocity Assisted Shape-Based Tracking of Cardiac Non-Rigid Motion
Authors: John C. McEachen II, François G. Meyer, R. Todd Constable, Arye Nehorai, James S. Duncan
Venue: ICCV
Year: 1995

A framework for tracking pointwise periodic non-rigid motion of the heart's left ventricular (LV) wall is presented which incorporates information from two different magnetic resonance imaging (MRI) techniques. New developments in phase-contrast cine MR imaging have produced spatial maps of instantaneous velocity that heave proven accuracy within the myocardium, or wall, of the heart. This information is combined with shape-based matching techniques to provide improved estimates of trajectories, especially in regions where shape information is limited. These raw trajectories act as input to a recursive least squares (RLS) filter which applies the constraints of temporal periodicity and spatial smoothness for the final estimate. The results of the RLS filter are compared with the motion of actual implanted markers. Comparisons are also made between exclusively shape-based filtered and phase-contrast enhanced trajectory estimates using both phantom and actual canine heart MR images.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Topologically Adaptable Snakes
Authors: Tim McInerney, Demetri Terzopoulos
Venue: ICCV
Year: 1995

The paper presents a typologically adaptable snakes model for image segmentation and object representation. The model is embedded in the framework of domain subdivision using simplicial decomposition. This framework extends the geometric and topological adaptability of snakes while retaining all of the features of traditional snakes, such as user interaction, and overcoming many of the limitations of traditional snakes. By superposing a simplicial grid over the image domain and using this grid to iteratively reparameterize the deforming snakes model, the model is able to flow into complex shapes, even shapes with significant protrusions or branches, and to dynamically change topology as necessitated by the data. Snakes can be created and can split into multiple parts or seamlessly merge into other snakes. The model can also be easily converted to and from the traditional parametric snakes model representation. We apply a 2D model to various synthetic and real images in order to segment objects with complicated shapes and topologies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Unifying Framework for Structure and Motion Recovery from Image Sequences
Authors: Philip F. McLauchlan, David William Murray 0001
Venue: ICCV
Year: 1995

The paper proposes a statistical framework that enables 3D structure and motion to be computed optimally from an image sequence, on the assumption that feature measurement errors are independent and Gaussian distributed. The analysis and results demonstrate that computing both camera/scene motion and 3D structure is essential to computing either with any accuracy. Having computed optimal estimates of structure and motion over a small number of initial images, a recursive version of the algorithm (previously reported) recomputes sub optimal estimates given new image data. The algorithm is designed explicitly for real time implementation, and the complexity is proportional to the number of tracked features. 3D projective, affine and Euclidean models of structure and motion recovery have been implemented, incorporating both point and line features into the computation. The framework can handle any feature type and camera model that may be encapsulated as a projection equation from scene to image.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Rigidity Checking of 3D Point Correspondences under Perspective Projection
Authors: Daniel P. McReynolds, David G. Lowe
Venue: ICCV
Year: 1995

An algorithm is described which rapidly verifies the potential rigidity of three dimensional point correspondences from a pair of three dimensional views under perspective projection. The output of the algorithm is a simple yes or no answer to the question "Could these corresponding points from two views be the projection of a rigid configuration?" Potential applications include 3D object recognition from a single previous view and correspondence matching for stereo or motion over widely separated views. Rigidity checking verifies point correspondences by using 3D recovery equations as a matching condition. The proposed algorithm improves upon other methods that fall under this approach because it works with as few as six corresponding points under full perspective projection, handles correspondences from widely separated views, makes full use of the disparity of the correspondences, and is integrated with a linear algorithm for 3D recovery due to Kontsevich (1991). Results are given for experiments with synthetic and real image data. A complete implementation of this algorithm is being made publicly available.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Determining Facial Expressions in Real-Time
Authors: Yael Moses, David Reynard, Andrew Blake 0001
Venue: ICCV
Year: 1995

We suggest an approach to describing and tracking the deformation of facial features. We concentrate on the mouth since its shape is important in detecting emotion. However, we believe that our system could be extended to deal with other facial features. In our system, the mouth is described by a valley contour which is based between the lips. This contour is shown to exist independently of illumination, viewpoint, identity, and expression. We present a real time mouth tracking system that follows this valley. It is shown to be robust to changes in identity, illumination and viewpoint. A simple classification algorithm was found to be sufficient to discriminate between 5 different mouth shapes, with a 100% recognition rate.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Automatic Generation of GRBF Networks for Visual Learning
Authors: Shayan Mukherjee, Shree K. Nayar
Venue: ICCV
Year: 1995

Learning can often be viewed as the problem of mapping from an input space to an output space. Examples of these mappings are used to construct a continuous function that approximates given data and generalizes for intermediate instances. Generalized Radial Basis Function (GRBF) networks are used to formulate this approximating function. A novel method is introduced to construct an optimal GRBF network for a given mapping and error bound using the integral wavelet transform. Simple one-dimensional examples are used to demonstrate how the optimal network is superior to one constructed using standard ad hoc optimization techniques. The paper concludes with an application of optimal GRBF networks to object recognition and pose estimation. The results of this application are favorable.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Real-Time Focus Range Sensor
Authors: Shree K. Nayar, Masahiro Watanabe, Minori Noguchi
Venue: ICCV
Year: 1995

Structures of dynamic scenes can only be recovered using a real-time range sensor. Depth-from-defocus offers a direct solution to fast and dense range estimation. It is computationally efficient as it circumvents the correspondence problem faced by stereo and feature tracking in structure-from-motion. However, accurate depth estimation requires theoretical and practical solutions to a variety of problems including the recovery of textureless surfaces, precise blur estimation, and magnification variations caused by defocusing. Both textured and textureless surfaces are recovered using an illumination pattern that is projected via the same optical path used to acquire images. The illumination pattern is optimized to ensure maximum accuracy and spatial resolution in the computed depth. The relative blurring in two images is computed using a narrow-band linear operator that is designed by considering all the optical, sensing and computational elements of the depth-from-defocus system. Defocus-invariant magnification is achieved by the use of an additional aperture in the imaging optics. A prototype focus range sensor has been developed that produces up to 512/spl times/480 depth estimates at 30 Hz with an accuracy better than 0.3%. Several experimental results are included to demonstrate the performance of the sensor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Deformable Velcro(tm) Surfaces
Authors: Walter M. Neuenschwander, Pascal Fua, Gábor Székely, Olaf Kübler
Venue: ICCV
Year: 1995

We present a new approach to segmentation of 3-D shapes that initializes and then optimizes a 3-D surface model given only the data and a very small number of 3-D seed points and corresponding surface normals. This is a valuable capability for medical, robotic and cartographic applications where such seed points can be naturally supplied. In effect, the surface model is clamped onto the object boundary in manner reminiscent of a Velcro being closed. We develop the method's mathematic framework and show preliminary results using volumetric medical data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Detecting Kinetic Occlusion
Authors: Sourabh A. Niyogi
Venue: ICCV
Year: 1995

Visual motion boundaries provide a powerful cue for the perceptual organization of scenes. Motion boundaries are present when surfaces in motion occlude one another. Conventional approaches to motion analysis have relied on assumptions of data conservation and smoothness, which has made analysis of motion boundaries difficult. We show that a common source of motion boundary, kinetic occlusion, can be detected using spatiotemporal junction analysis. Junction analysis is accomplished by utilizing distributed representations of motion used in models of human visual motion sensing. By detecting changes in the direction of motion in these representations, spatiotemporal junctions are detected in a manner which differentiates accretion from deletion. We demonstrate successful occlusion detection on spatiotemporal imagery containing occluding surfaces in motion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Theory of Specular Surface Geometry
Authors: Michael Oren, Shree K. Nayar
Venue: ICCV
Year: 1995

A theoretical framework is introduced for the perception of specular surface geometry. When an observer moves in three-dimensional space, real scene features, such as surface markings, remain stationary with respect to the surfaces they belong to. In contrast, a virtual feature, which is the specular reflection of a real feature, travels on the surface. Based on the notion of caustics, a novel feature classification algorithm is developed that distinguishes real and virtual features from their image trajectories that result from observer motion. Next, using support functions of curves, a closed-form relation is derived between the image trajectory of a virtual feature and the geometry of the specular surface it travels on. It is shown that in the 2D case where camera motion and the surface profile are coplanar, the profile is uniquely recovered by tracking just two unknown virtual features. Finally, these results are generalized to the case of arbitrary 3D surface profiles that are travelled by virtual features when camera motion is not confined to a plane. An algorithm is developed that uniquely recovers 3D surface profiles using a single virtual feature tracked from the occluding boundary of the object. All theoretical derivations and proposed algorithms are substantiated by experiments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Matching of 3D Curves Using Semi-Differential Invariants
Authors: Tomás Pajdla, Luc Van Gool
Venue: ICCV
Year: 1995

A method for matching 3-D curves under Euclidean motions is presented. Our approach uses a semi-differential invariant description requiring only first derivatives and one reference point, thus avoiding the computation of high order derivatives. A novel curve similarity measure building on the notion of /spl epsiv/-reciprocal correspondence is proposed. It is shown that by combining /spl epsiv/-reciprocal correspondence with the robust least median of squares motion estimation, the registration of partially occluded curves can be accomplished. An experiment with real curves extracted from 3-D surfaces demonstrates that curve matching can be successfully performed even on data from a simple and cheap 3-D sensor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Structure and Semi-Fluid Motion Analysis of Stereoscopic Satellite Images for Cloud Tracking
Authors: Kannappan Palaniappan, Chandra Kambhamettu, Frederick Hasler, Dmitry B. Goldgof
Venue: ICCV
Year: 1995

Time-varying multispectral observations of clouds from meteorological satellites are used to estimate cloud-top heights (structure) and cloud winds (semi-fluid motion). Stereo image pairs over several time steps were acquired by two geostationary satellites with synchronized scanning instruments. Cloud-top height estimation from these image pairs is performed using an improved automatic stereo analysis algorithm on a massively parallel Maspar computer with 16 K processors. A new category of motion behavior known as semi-fluid motion is described for modeling cloud motions and an automatic algorithm for extracting semi-fluid motion is developed to track cloud winds. The time sequential dense estimates of cloud-top height depth maps in conjunction with intensity data are used to estimate local semi-fluid motion parameters for cloud tracking. Both stereo disparities and motion correspondences are estimated to sub-pixel accuracy. The Interactive Image SpreadSheet (IISS) is a new versatile visualization tool that was enhanced to analyze and visualize the results of the stereo analysis and semi-fluid motion estimation algorithms. Experimental results using time-varying data of the visible channel from two satellites in geosynchronous orbit is presented for the Hurricane Frederic.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Results Using Random Field Models for the Segmentation of Color Images of Natural Scenes
Authors: Dileep Kumar Panjwani, Glenn Healey
Venue: ICCV
Year: 1995

We present results using a Markov random field color texture model for the unsupervised segmentation of images of outdoor scenes. The color random field model describes textured regions in terms of spatial interaction within color bands and between different color bands. The model is used by a segmentation algorithm based on agglomerative hierarchical clustering. At the heart of the clustering is a step wise optimal merging process that at each iteration maximizes a global performance functional. The test for stopping the clustering is based on changes in the likelihood of the image. We provide experimental results that demonstrate the performance of the segmentation algorithm on color images of natural scenes. Most of the processing during segmentation is local making the algorithm amenable to high performance parallel implementation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Volumetric Deformable Models with Parameter Functions: A New Approach to the 3D Motion Analysis of the LV from MRI-SPAMM
Authors: Jinah Park, Dimitris N. Metaxas, Leon Axel
Venue: ICCV
Year: 1995

We present a new method for analyzing the 3D motion of the heart's left ventricle (LV) from tagged magnetic resonance imaging (MRI) data. Our technique is based on the development of a new class of volumetric physics-based deformable models whose parameters are functions and can capture the local shape variation of an object. These parameters require no complex post-processing in order to be used by a physician. These volumetric models allow the accurate estimation of the shape and motion of the inner and outer walls of the LV as well as within the walls. We also present a new technique for calculating forces exerted by tagged MRI data to material points of the deformable model. Furthermore, by plotting the variations over time of the extracted LV model parameters from normal heart data we are able to quantitatively analyze and compare the epicardial and endocardial motion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Shape Extraction for Curves Using Geometry-Driven Diffusion and Functional Optimization
Authors: Eric J. Pauwels, Peter Fiddelaers, Luc Van Gool
Venue: ICCV
Year: 1995

In this paper we show how both geometry-driven diffusion and optimization of the Mumford-Shah functional can be used to develop a type of curve-evolution that is able to preserve salient features of closed curves (such as corners and straight line segments), while simultaneously suppressing noise and irrelevant details. The idea is to characterize the curve by means of its angle-function (i.e. the angle between the tangent and a fixed axis) and to apply the appropriate dynamics to this one-dimensional representation. We show how constrained evolution equations can be used to keep the corresponding curve closed at all times.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The Nonparametric Approach for Camera Calibration
Authors: MaoLin Qiu, Song De Ma
Venue: ICCV
Year: 1995

Discusses a nonparametric approach for calibrating a CCD camera, a constrained topological mapping (CTM) approach to analyze the systematic imaging errors of an image system and compare it with parametric approaches which are based on optimization and have been discussed by many other authors. This nonparametric approach has several distinct features. In this approach, some distortion surfaces are derived directly from the training samples. Because no analytical form of these surfaces is assumed, when we modeled the distortions by a nonparametric model, the systematic imaging errors instead of mere lens distortions are considered. This gives an new approach to analyze the imaging errors of a particular imaging system. Experimental results are given in detail, which indicate that both in image projection and in 3D reconstruction, the accuracy is much improved when the nonparametric approach is employed for calibrating a camera.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A Snake for Model-Based Segmentation
Authors: Petia Radeva, Joan Serrat 0002, Enric Martí
Venue: ICCV
Year: 1995

Despite the promising results of numerous applications, the hitherto proposed snake techniques share some common problems: snake attraction by spurious edge points, snake degeneration (shrinking and flattening), convergence and stability of the deformation process, snake initialization and local determination of the parameters of elasticity. We argue here that these problems can be solved only when all the snake aspects are considered. The snakes proposed here implement a new potential field and external force in order to provide a deformation convergence, attraction by both near and far edges as well as snake behaviour selective according to the edge orientation. Furthermore, we conclude that in the case of model-based segmentation, the internal force should include structural information about the expected snake shape. Experiments using this kind of snakes for segmenting bones in complex hand radiographs show a significant improvement.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Weakly-Calibrated Stereo Perception for Rover Navigation
Authors: Luc Robert, Michel Buffa, Martial Hebert
Venue: ICCV
Year: 1995

Presents a vision system for autonomous navigation based on stereo perception without 3D reconstruction. This approach uses weakly calibrated stereo images, i.e. images for which only the epipolar geometry is known. The vision system first rectifies the images, matches selected points between the two images, and then computes the relative elevation of the points relative to a reference plane as well as the images of their projections on this plane. We have integrated this vision module into a complete navigation system. In this system, the relative elevation is used as a shape indicator in order to compute appropriate steering directions everytime a new stereo pair is processed. We have conducted initial experiments in unstructured, outdoor environments with an wheeled rover.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Perceptual Organization in an Interactive Sketch Editing Application
Authors: Eric Saund, Thomas P. Moran
Venue: ICCV
Year: 1995

The paper shows how techniques from computational vision can be deployed to support interactive sketch editing. While conventional computer supported drawing tools give users access to visible marks or image objects at a single level of abstraction, a human user's visual system rapidly constructs complex groupings and associations among image elements according to his or her immediate purposes. We have been exploring perceptually supported sketch editors in which computer vision algorithms run continuously, behind the scenes, to afford users efficient access to emergent visual objects in a drawing. We employ a flexible image interpretation architecture based on token grouping in a multiscale blackboard data structure. This organization supports multiple perceptual interpretations of line drawing data, domain specific knowledge bases for interpreting visual structures, and natural gesture based selection of visual objects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>