OpenRaiser/Intern-Atlas huggingface dataset:
The scale space aspect graph
Authors: David W. Eggert, Kevin W. Bowyer, Charles R. Dyer, Henrik I. Christensen, Dmitry B. Goldgof
Venue: CVPR
Year: 1992

Currently the aspect graph is computed from the theoretical standpoint of perfect resolution in object shape, the viewpoint and the projected image. This means that the aspect graph may include details that an observer could never see in practice. Introducing the notion of scale into the aspect graph framework provides a mechanism for selecting a level of detail that is "large enough" to merit explicit representation. This effectively allows control over the number of nodes retained in the aspect graph. This paper introduces the concept of the scale space aspect graph, defines three different interpretations of the scale dimension, and presents a detailed example for a simple class of objects, with scale defined in terms of the spatial extent of features in the image.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Constructing perceptual categories
Authors: Jacob Feldman
Venue: CVPR
Year: 1992

It is shown how a parameterization of the structure of the observed object (interpretable as the space of dimensions of generative operations which brought the object into existence) entails a lattice that enumerates all the allowable categories and subcategories for the class of object, along with an inferential preference hierarchy among them. Each model is constrained to be generic in its parameterization, so that each node in the lattice stands in for an entire class of objects that, all being parameterized the same way, can all be treated as equivalent to one another: the observed object's natural category.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Multi-resolution shape description by corners
Authors: Cornelia Fermüller, Walter G. Kropatsch
Venue: CVPR
Year: 1992

A robust method for describing planar curves in multiple resolution using curvature information is presented. The method is developed by taking into account the discrete nature of digital images as well as the discrete aspect of a multiresolution structure (pyramid). The main contribution lies in the robustness of the technique, which is due to the additional information that is extracted from observing the behavior of corners in the whole pyramid. Furthermore, the resulting algorithm is conceptually simple and easily parallelizable. Theoretical results are developed analyzing the curvature of continuous curves in scale-space and showing the behavior of curvature extrema under varying scale. The results are used to eliminate any ambiguities that might arise from sampling problems due to the discreteness of the representation. Experimental results demonstrate the potential of the method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Saliencies and symmetries: toward 3D object recognition from large model databases
Authors: Patrick J. Flynn
Venue: CVPR
Year: 1992

The construction of interpretation tables from database models is introduced, and a recognition procedure using scene feature groups is discussed. Techniques for extraction of feature group equivalence classes and computation of feature group saliency are discussed. Two methods to reduce the computational burdens associated with a large model database are proposed and tested on polyhedral objects. The first method reduces the population of protohypotheses in the interpretation tables consulted during recognition by excluding redundant feature groups produced from object symmetries. The second method assigns a population-based numerical measure of saliency to each feature group retrieved from the scene; this measure allows only the most salient feature groups to be used in object recognition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Handprinted digit recognition using spatiotemporal connectionist models
Authors: Thomas Fontaine, Lokendra Shastri
Venue: CVPR
Year: 1992

A connectionist model for recognizing unconstrained handprinted digits is described. Instead of treating the input as a static signal, the image is canned over time and converted into a time-varying signal. The temporalized image is processed by a spatiotemporal connectionist network. The resulting system offers shift-invariance along the temporalized axis, a reduction in the number of free parameters, and the ability to process images of arbitrary length. For a set of real-world ZIP code digit images, the system achieved a 99.1% recognition rate on the training set and a 96.0% recognition rate on the test with no rejections. A 99.0% recognition rate on the test set was achieved when 14.6% of the images were rejected.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Recognizing 3D objects from 2D images: an error analysis
Authors: W. Eric L. Grimson, Daniel P. Huttenlocher, Tao Daniel Alter
Venue: CVPR
Year: 1992

Object recognition systems that use a small number of pairings of data and model features to compute the 3D transformation from model to sensor coordinates are considered. The effects of 2D sensor uncertainty on such computations are examined. The uncertainty in transformation parameters is bounded, and the effect of this uncertainty on false positive recognition rates is analyzed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Towards object-based heuristics
Authors: Ari David Gross
Venue: CVPR
Year: 1992

A survey and critique of previous work is given, and two object-based heuristics are developed. The structured nature of objects is the motivation for the nonaccidental alignment criterion; parallel lines within the object's bounding contour are related to the object-centered coordinate system. The regularity and symmetry inherent in many man-made objects is the motivation for the orthogonal basis constraint, an oblique set of coordinate axes in the image is presumed to be the projection of an orthogonal set of 3D coordinate axes in the scene. These heuristics are demonstrated on real and synthetic image contours.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A new 3-D surface measurement system using a structured light
Authors: Latifa Guisser, René Payrissat, Serge Castan
Venue: CVPR
Year: 1992

The authors present a 3-D measurement method using a projected grid that permits an optimal geometrical exploitation of the calculated 3-D data. They propose a reliable method for solving the correspondence that establishes the link between the imaged grid and the original grid curve per curve without any ambiguity. The imaged grid is extracted by an efficient method that describes the distorted grid as a network of curves rather than a graph, and hence provides regular and precise 2-D information. The 3-D projected grid is calculated per curve by using the triangulation principle. Thus, two independent families of 3-D curves that parameterize the object surfaces can be used for a surface geometrical study.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Classification trees with neural network feature extraction
Authors: Heng Guo 0002, Saul B. Gelfand
Venue: CVPR
Year: 1992

The ideal use of small multilayer nets at the decision nodes of a binary classification tree to extract nonlinear features is proposed. The nets are trained and the tree is grown using a gradient-type learning algorithm in the multiclass case. The method improves on standard classification tree design methods in that it generally produces trees with lower error rates and fewer nodes. It also reduces the problems associated with training large unstructured nets and transfers the problem of selecting the size of the net to the simpler problem of finding a tree of the right size. An efficient tree pruning algorithm is proposed for this purpose. Trees constructed with the method and the CART method are compared on a waveform recognition problem and a handwritten character recognition problem. The approach demonstrates significant decrease in error rate and tree size. It also yields comparable error rates and shorter training times than a large multilayer net trained with backpropagation on the same problems.
Recursive opening transform
Authors: Robert M. Haralick, Su S. Chen, Tapas Kanungo
Venue: CVPR
Year: 1992

The opening transformation on N-dimensional discrete space Z/sup N/ is discussed. The transform efficiently computes the binary opening (closing) with any size structuring element. It also provides a quick way to calculate the pattern spectrum of an image. The pattern spectrum is found to be nothing more than a histogram of the opening transform. An efficient two-pass recursive opening transform algorithm is developed and implemented. The correctness of the algorithm is proved, and some experimental results are given. The results show that the execution time of the algorithm is a linear function of n, where n is the product of the number of points in the structuring element. When the input binary image size is 256*256 and 50% of the image is covered by the binary-one pixels, it takes approximately 250 ms to do an arbitrary sized line opening and approximately 500 ms to do an arbitrary size box opening on the Sun/Sparc II workstation (with C compiler optimization flag on).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
CCD camera calibration and noise estimation
Authors: Glenn Healey, Raghava Kondepudy
Venue: CVPR
Year: 1992

The variation in digitized pixel values that is due to sensor noise and scene variation is quantified, using physical models for CCD (charge-coupled device) video cameras and material reflectance. This analysis forms the basis of algorithms for camera characterization and calibration and for surface description. The use of these techniques for estimating a measure of scene variation is described. This measure is independent of image irradiance and can be used to identify a surface from a single sensor band over a range of situations. Experimental results verify the models presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
3-D landmark recognition from range images
Authors: Martial Hebert
Venue: CVPR
Year: 1992

Progress in building and recognizing models of objects for an autonomous vehicle for on-road and cross-country navigation is reported. The object models are stored in a map and are used as landmarks for estimating vehicle position. The landmarks can be used as intermediate control points at which the vehicle must take some prescribed action in the case of a complex mission. Robust object tracking using sequences of range images and building and updating 3-D object representations is presented. Tracking uses object prediction from one image to the next to accurately compute object locations. Object representations are built by merging sets of points from individual images into a single set in an object-centered coordinate frame. The sparse set of points is then segmented into shapes yielding compact and general object representations. An algorithm for landmark identification in range images is introduced in the context of map-based navigation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Absolute orientation from uncertain point data: a unified approach
Authors: Yacov Hel-Or, Michael Werman
Venue: CVPR
Year: 1992

A general and flexible method for fusing and integrating different 2D and 3D measurements for pose estimation is proposed. The 2D measured data are viewed as 3D data with infinite uncertainty in a particular direction. This representation unifies the two categories of the absolute orientation problem into a single problem that varies only in the uncertainty values associated with the measurements. With this paradigm a uniform mathematical formulation of the problem is obtained, and different kinds of measurements that can be fused to obtain a better solution. The method, which is implemented using Kalman filtering, is robust and easily parallelizable.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
A deformable region model using stochastic processes applied to echocardiographic images
Authors: Isabelle Herlin, C. Nguyen, Christine Graffigne
Venue: CVPR
Year: 1992

The problem of improving an initial segmentation of medical data by making use of gray level, texture, and gradient information is addressed. The mathematical environment is that of Markov random fields and stochastic processes. This yields two major advantages: automatic selection of program parameters and ergonomic software that can be used to test homogeneity properties of regions. The method is applied to echocardiographic images in order to segment cardiac cavities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Exploratory active vision: theory
Authors: Jean-Yves Hervé, Yiannis Aloimonos
Venue: CVPR
Year: 1992

An active approach to the integration of shape from x modules-here shape from shading and shape from texture-is proposed. The question of what constitutes a good motion for the active observer is addressed. Generally, the role of the visual system is to provide depth information to an autonomous robot; a trajectory module will then interpret it to determine a motion for the robot, which in turn will affect the visual information received. It is suggested that the motion can also be chosen so as to improve the performance of the visual system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Model based region segmentation using cooccurrence matrices
Authors: Stéphane Houzelle, Gérard Giraudon
Venue: CVPR
Year: 1992

A region segmentation algorithm is presented, using a model for joint probability density. Joint probability density can be defined as an N*N cooccurrence matrix in which each coordinate (i, j) gives the probability for the gray-level transition i, j between two neighbor pixels. The approach consists in modeling the energy distribution within a cooccurrence matrix of a region. Regions are assumed to be stationary. A region-growing scheme that proceeds in two steps is used. The first step consists of learning the parameters of the model. The second step is the segmentation process. Starting with a seed pixel, new pixels are incorporated in the region if their neighborhoods fit the model.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The geometry of visual interception
Authors: Liuqing Huang, Yiannis Aloimonos
Venue: CVPR
Year: 1992

Under the traditional paradigm of considering vision as a recovery problem, visual interception is just another application of the structure-from-motion module. However, the inherent difficulties of three-dimensional reconstruction have delayed any real-time applications. The authors offer a robust solution under the active qualitative vision paradigm. From the image intensity function, they obtain the locomotive intrinsics of the agent and the target. Based on this relative information, they present a control strategy that decides in real time whether the velocity of the agent should be increased or decreased at any time instant, thus guiding the agent to intercept the target. The problem of visual interception can thus be solved by simple computation without correspondence.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Adaptive-size physically-based models for nonrigid motion analysis
Authors: Wen-Chen Huang, Dmitry B. Goldgof
Venue: CVPR
Year: 1992

Adaptive-size physically based models suitable for nonrigid motion analysis are presented. The mesh size increases or decreases dynamically during the surface reconstruction process to locate nodes near surface areas of interests (like high curvature points) and to optimize the fitting error. A priori information about nonrigidity can be included so that the surface model deforms to fit moving data points while preserving some basic nonrigid constraints (e.g. isometry or conformality). Implementation of the proposed algorithm with and without isometric/conformal constraints is presented. Performance and accuracy of derived algorithms are demonstrated on data simulating deforming ellipsoidal and bending planar shapes. The algorithm is applied to the real range data for bending paper and to volumetric temporal left ventricular data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Comparing images using the Hausdorff distance under translation
Authors: Daniel P. Huttenlocher, William Rucklidge, Gregory A. Klanderman
Venue: CVPR
Year: 1992

Efficient algorithms are provided for computing the Hausdorff distance between a binary image and all possible relative positions (translations) of a model, or a portion of that model. The computation is in many ways similar to binary correlation. However, it is more tolerant of perturbations in the locations of points because it measures proximity rather than exact superposition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Recognizing assembly tasks using face-contact relations
Authors: Katsushi Ikeuchi, Takashi Suehiro
Venue: CVPR
Year: 1992

A novel method for programming a robot, called the assembly-plan-from-observation (APO) method, is proposed. The APO method aims to build a system that has the capability of observing a human performing an assembly task, understanding the task based on the observation, and generating the robot program to achieve the same task. Assembly relations that serve as the basic representation of each assembly task are defined. It is verified that such assembly relations can be recovered from the observation of human assembly tasks, and that from such assembly relations it is possible to generate robot motion commands to repeat the same assembly task. An APO system based on the assembly relations is demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Space efficient 3-D model indexing
Authors: David W. Jacobs
Venue: CVPR
Year: 1992

It is shown that the set of 2-D images produced by a group of 3-D point features of a rigid model can be optimally represented with two lines in two high-dimensional spaces. This result is used to match images and model groups by table lookup. The table is efficiently built and accessed through analytic methods that account for the effect of sensing error. In real images, it reduces the set of potential matches by a factor of several thousand. This representation of a model's images is used to analyze two other approaches to recognition. It is determined when invariants exist in several domains, and it is shown that there is an infinite set of qualitatively similar nonaccidental properties.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
On texture in document images
Authors: Anil K. Jain 0001, Sushil K. Bhattacharjee, Yao Chen
Venue: CVPR
Year: 1992

A multichannel filtering-based texture segmentation method is applied to a variety of document image processing problems: text-graphics separation, address-block location, and bar code localization. In each of these segmentation problems, the text context or bar code in the image is considered to define a unique texture. Thus, all three document analysis problems can be posed as texture segmentation problems. Two-dimensional Gabor filters are used to compute texture features. Both supervised and unsupervised methods are used to identify regions of text or bar code in the document images. The performance of the segmentation and classification scheme for a variety of document images demonstrates the generality and effectiveness of the approach.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Shadow identification
Authors: Caixia Jiang, Matthew O. Ward
Venue: CVPR
Year: 1992

A shadow identification and classification method for real images is developed. The method is based on extensive analysis of shadow intensity and shadow geometry. The procedure for identifying shadows is divided into low-level, middle-level, and high-level processes. The low-level extracts dark regions from images. The middle-level process performs feature analysis on dark regions, including detecting vertices on the outlines of dark regions, identifying penumbrae in dark regions, assigning the subregions in dark regions as self-shadows and cast shadows, and finding object regions adjacent to dark regions. The high-level process integrates the information derived from the previous processes and confirms shadows among the dark regions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Point correspondence recovery in non-rigid motion
Authors: Chandra Kambhamettu, Dmitry B. Goldgof
Venue: CVPR
Year: 1992

A method for the estimation of point correspondences on a surface undergoing nonrigid motion, based on changes in Gaussian curvature, is described. An approach for estimating the point correspondences and stretching of a surface undergoing conformal motion with constant (homothetic), linear, or polynomial stretching is proposed. Small motion assumption is utilized to hypothesize all possible point correspondences. Curvature changes are then computed for each hypothesis. The difference between computed curvature changes and the one predicted by the conformal motion assumption is calculated. The hypothesis with the smallest error gives point correspondences between consecutive time frames. Simulations performed on ellipsoidal data illustrate the performance and accuracy of derived algorithms. The algorithm is applied to volumetric CT data of the left ventricle of a dog's heart.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Morphological decomposition of restricted domains: a vector space solution
Authors: Tapas Kanungo, Robert M. Haralick
Venue: CVPR
Year: 1992

Restricted domains, which are a restricted class of 2-D shapes, are defined. It is proved that any restricted domain can be decomposed as n-fold dilations of thirteen basis structuring elements and hence can be represented in a thirteen-dimensional space. This thirteen-dimensional space is spanned by the thirteen basis structuring elements comprising of lines, triangles, and a rhombus. It is shown that there is a linear transformation from this thirteen-dimensional space to an eight-dimensional space wherein a restricted domain is represented in terms of its side lengths. Furthermore, the decomposition in general is not unique, and all the decompositions can be constructed by finding the homogeneous solutions of the transformation and adding it to a particular solution. An algorithm for finding all possible decompositions is provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>