Showing papers on "Orientation (computer vision) published in 1985"

Uncertainty relation for resolution in space, spatial frequency, and orientation optimized by two-dimensional visual cortical filters.

Abstract: Two-dimensional spatial linear filters are constrained by general uncertainty relations that limit their attainable information resolution for orientation, spatial frequency, and two-dimensional (2D) spatial position. The theoretical lower limit for the joint entropy, or uncertainty, of these variables is achieved by an optimal 2D filter family whose spatial weighting functions are generated by exponentiated bivariate second-order polynomials with complex coefficients, the elliptic generalization of the one-dimensional elementary functions proposed in Gabor’s famous theory of communication [ J. Inst. Electr. Eng.93, 429 ( 1946)]. The set includes filters with various orientation bandwidths, spatial-frequency bandwidths, and spatial dimensions, favoring the extraction of various kinds of information from an image. Each such filter occupies an irreducible quantal volume (corresponding to an independent datum) in a four-dimensional information hyperspace whose axes are interpretable as 2D visual space, orientation, and spatial frequency, and thus such a filter set could subserve an optimally efficient sampling of these variables. Evidence is presented that the 2D receptive-field profiles of simple cells in mammalian visual cortex are well described by members of this optimal 2D filter family, and thus such visual neurons could be said to optimize the general uncertainty relations for joint 2D-spatial–2D-spectral information resolution. The variety of their receptive-field dimensions and orientation and spatial-frequency bandwidths, and the correlations among these, reveal several underlying constraints, particularly in width/length aspect ratio and principal axis organization, suggesting a polar division of labor in occupying the quantal volumes of information hyperspace. Such an ensemble of 2D neural receptive fields in visual cortex could locally embed coarse polar mappings of the orientation–frequency plane piecewise within the global retinotopic mapping of visual space, thus efficiently representing 2D spatial visual information by localized 2D spectral signatures.

Image space shading of 3-dimensional objects

Abstract: Two-dimensional images of 3D objects require realistic shading to create the illusion of depth. Traditional (object space) shading methods require extra data (normal vectors) to be stored with the object description. When object representations are obtained directly from measured data, these normal vectors may be expensive to compute; if the object is modified interactively, they must be recomputed frequently. To avoid these problems a simple shading method is devised which uses only information available in image space, after coordinates have been transformed, hidden surfaces removed, and a complete pre-image of all objects has been assembled. The method uses both the distance from the light source and the surface orientation as the basis for shading. The theory and its implementation are discussed and shaded images of a number of objects are presented.

High-speed image generation of complex solid objects using octree encoding

Abstract: An image generator for generating two-dimensional images of three-dimensional solid objects at a high speed defines a scene to be displayed within a cuboid three-dimensional universe which has been hierarchically subdivided into a plurality of discrete volumes of uniform size and similar orientation. The three-dimensional universe is represented by a tree structure having a plurality of nodes, one for each volume in the three-dimensional universe which is at least partially occupied by objects in the scene. A user may select a point of view for viewing the object. Nodes in the tree structure representing the three-dimensional universe are visited in a sequence determined by the point of view selected by the user so that nodes corresponding to volumes which are unobstructed by other volumes are visited first. Each visited node which is enclosed by the object is projected onto a subdivided view plane organized into a hierarchy of a plurality of discrete areas. Areas of the view plane which are completely enclosed by the projection are painted onto a display screen. Areas which intersect but are not enclosed by the projection are further subdivided to locate those areas which are enclosed. A representation of the hierarchically-subdivided view plane arranged in a tree structure is stored in a store. Each time an area of the view plane is painted, an entry in the representation of the view plane corresponding to that area is marked. The corresponding entry in the representation of the view plane is checked before an area is painted, to ensure that no area is painted more than once so that hidden surfaces are not displayed. To create sectional views, a user may define a region of the three-dimensional universe, and volumes outside of that region are not projected. Due to the hierarchical structure of the three-dimensional universe and the two-dimensional view plane, the symmetry of subdivisions, and the resulting simplicity of the calculations necessary to create an image, real time image generation wherein calculations necessary to create the image are performed by hard-wired digital logic elements to increase speed performance is possible.

Applications of Tensor Theory to Object Recognition and Orientation Determination

Abstract: A method is developed by which images resulting from orthogonal projection of rigid planar-patch objects arbitrarily oriented in three-dimensional (3-D) space may be used to form systems of linear equations which are solved for the affine transform relating the images. The technique is applicable to complete images and to unlabeled feature sets derived from images, and with small modification may be used to transform images of unknown objects such that they represent images of those objects from a known orientation, for use in object identification. No knowledge of point correspondence between images is required. Theoretical development of the method and experimental results are presented. The method is shown to be computationally efficient, requiring O(N) multiplications and additions where, depending on the computation algorithm, N may equal the number of object or edge picture elements.

Early orientation selection: Tangent fields and the dimensionality of their support

Abstract: Orientation selection is the inference of orientation information out of images. It is one of the foundations on which other visual structures are built, since it must precede the formation of contours out of pointillist data and surfaces out of surface markings. We take a differential geometric view in defining orientation selection, and develop algorithms for actually doing it. The goal of these algorithms is formulated in mathematical terms as the inference of a vector field of tangents (to the contours), and the algorithms are studied in both abstract and computational forms. They are formulated as matching problems, and algorithms for solving them are reduced to biologically plausible terms. We show that two different matching problems are necessary, the first for 1-dimensional contours (which we refer to as Type I processes) and second for 2-dimensional flows (or Type II processes). We conjecture that this difference is reflected in the response properties of “simple” and “complex” cells, respectively, and predict several other psychophysical phenomena.

Image composition system

Abstract: The image composition system includes framestores 30, 31 for receiving information from first and second picture sources. A processor 33 provides the composed image by using information from these sources. The processor is controlled by picture shape information made available from a third framestore 32. This shape information may be provided by a camera 26 receiving an image of a silhouette for example or the shape can be manually generated via a touch tablet 38. The instantaneous value of the shape controls the blending of the pictures such that portions of the picture can be taken from a scene and inserted without noticeable degradation. Manipulation of the position, orientation or size of the inserted picture portion for example can also be effected.

Method and apparatus for obtaining three dimensional tomographic images by interpolation of a plurality of projection slice data bind for obtaining projection data for a chosen slice

Abstract: According to a scan planning method for obtaining any tomographic image by a CT system, projection data of a plurality of parallel slices is acquired by a computed tomographic scanning device. The tomographic images are interpolated in accordance with the tomographic data of the slices which is obtained by the CT scanning device thereby providing the three-dimensional image data. A three-dimensional object image is then displayed on a display in accordance with the three-dimensional image data. A viewpoint for the object image changes, and an orientation angle of the object image changes in accordance with a manually input coordinate information. A slice position image representing the designated position and angle of the slice is displayed three-dimensionally in accordance with the coordinate information. The CT scanning device is controlled in accordance with the position and angle of the slice position image with respect to the object image.

Method for identifying three-dimensional objects using two-dimensional images

Abstract: For recognizing a three-dimensional object from its two-dimensional image which was produced e.g. by a TV camera, a Hough transform representation is generated of the image and specific configurations or structures of the cluster points which constitute the Hough transform representation are determined. The information about these specific configurations is compared to similar information stored for the Hough representation of known object models. By thus relating portions of the image to portions of one or several object models, vertices of the image which are present at line or edge intersections, are related to vertices of the known object model(s). This knowledge about the correspondence of model and object vertex points allows the exact fitting of vertices and thus recognition of the unknown object and its relative orientation. The models may be either primitive objects and the procedure determines of which primitives the unknown object is composed, or the models may be wire frame models each of which completely describes one more complicated object and the procedure determines to which of the models the entire unknown object fits best.

On the Uniqueness of Image Flow Solutions for Planar Surfaces in Motion

Abstract: : Two important results relating to the uniqueness of image flow solutions for planar surfaces in motion are presented here These results relate to the formulation of the image flow problem by Waxman and Ullman which is based on a kinematic analysis of the image flow field The first result concerns resolving the duality of interpretations that are generally associated with the instantaneous image flow of an evolving image sequence It is shown that the interpretation for orientation and motion of planar surfaces is unique when either two successive image flows of one planar surface patch are given or one image flow of two planar patches moving as a rigid body is given This document has proved this by driving explicit expressions for the evolving solution of an image flow sequence with time These expressions can be used to resolve this ambiguity of interpretation in practical problems The second result is the proof of uniqueness for the velocity of approach which satisfies the image flow equations for planar surfaces derived in Waxman's and Ullman's document In addition, it is shown that this velocity can be computed as the middle root of a cubic equation These two results together suggest a new method for solving the image flow problem for planar surfaces in motion Additional keywords: image flow equations

Real-time gray-scale video processing using a moment- generating chip

Abstract: A system for performing visual processing on gray-scale images in real time (60 Hz) has been constructed. The custom VLSI moment generator chip computes area, center of gravity, orientation, and size. An image preprocessor allows separate moments to be computed for separate regions. A standard set of buses allows new processing elements to be easily added. The system is expected to find application in real-time sensor-based electronic assembly and in automated inspection and registration tasks. A simple application to a real-time visually servoed robot task is summarized.

Triangular Spect System for 3-D Total Organ Volume Imaging: Design Concept and Preliminary Imaging Results

Abstract: SPECT systems based on 2-D detectors for projection data collection and filtered back-projection image reconstruction have the potential for true 3-D imaging, providing contiguous slice images in any orientation. Anger camera-based SPECT systems have the natural advantage supporting planar imaging clinical procedures. However, current systems suffer from two drawbacks; poor utilization of emitted photons, and inadequate system design for SPECT. A SPECT system consisting of three rectangular cameras with radial translation would offer the variable cylindrical FOV of 25 cm to 40 cm diameter allowing close detector access to the object. This system would provide optimized imaging for both brain and body organs in terms of sensitivity and resolution. For brain imaging a tight detector triangle with fan beam collimation, matching detector UFOV to the head, allows full 2? utilization of emitted photons, resulting in >4 times sensitivity increase over the single detector system. Minification of intrinsic detector resolution in fan beam collimation further improves system resolution. For body organ imaging the three detectors with parallel hole collimators, rotating in non-circular orbit, provide both improved resolution and three-fold sensitivity increase. Practical challenges lie in ensuring perfect image overlap from three detectors without resolution degradation and artifact generation in order to benefit from the above improvements. An experimental system has been developed to test the above imaging concept and we have successfully demonstrated the superior image quality of the overlapped images. Design concept will be presented with preliminary imaging results.

A Computer Generated Hologram For Diffraction-Pattern Sampling

Abstract: Diffraction pattern sampling provides a feature space suitable for object classification, orientation and inspection. It allows significant dimensionality reduction. These properties are best achieved by the use of specifically-shaped Fourier transform plane detector elements and this can be realized with considerable flexibility, reduced size and improved performance by the use of computer generated holograms.

Visual Half-Field Symmetry in Orientation Perception

Abstract: The perception of orientation in the left and right visual half-fields has been investigated. No evidence for interfield differences was obtained for the discrimination of single lines by line matching or in magnitude of the systematic orientation distortion in orientation contrast and rod-and-frame experiments. Furthermore, increasing the time interval between test and comparison lines in successive matching provides no evidence for a differential operation of short-term spatial memory in the two hemispheres. It is concluded that hemispheric asymmetries do not arise at the level of sensory processing of spatial signals.

Determining Object Orientation Using Ellipse Fitting

Abstract: Many industrial applications of computer vision require fast, accurate, classification and orientation of known objects. For those objects which exhibit circular markings or circular surfaces, it is possible to determine object orientation from a single visual image. In this paper, a technique is presented which uses the parameters of an ellipse fit to points in the image to specify the orientation of the corresponding circular object surface. Location of candidate ellipse points in the image is accomplished by exploiting knowledge about object boundaries and image intensity gradients. A second order ellipse equation is fit to the candidate points using a nonlinear error measure based on the equation of a general conic and an average gradient constraint. The technique presented is applied to the task of estimating the orientation of a discrete transistor against a uniform background, and results are summarized for 138 images.

Device for producing double sided reproductions from books

Abstract: The device serves the aim of producing from books which because of an old or very strong binding allow only a small aperture angle virtual mirror images, with or without maintaining the orientation, for the purpose of better legibility, for preparing photographs or copies. It is characterised in that the book is placed on transparent plates arranged in the shape of a roof, and that a plurality of mirror arrangements are used simultaneously or sequentially to produce virtual images of the book pages in the same virtual image plane while simultaneously setting the spacing of these images relative to one another. Emphasis is placed on an illuminating device for those mirror arrangements which serve the purpose of stripwise image transmission, and on a plate arrangement for setting the mutual spacing of the virtual images.

A model of mental imagery

Abstract: A spatial image is a representation of a scene which encodes the spatial location, distance away, surface orientation and movement of each visible surface in the scene. Mental images are spatial images which are held and transformed by a neural network called spatial memory. Spatial memory is a large two-dimensional array of processors called spatial locations which operate in parallel under the control of a single supervising processor. Though held in spatial memory, mental images are independent of it, and can be transformed, shifted and rotated by transforming and moving image parts among the spatial locations. The architecture and control structure of spatial memory are presented as are details of its operation in translating, scaling and rotating mental images of three-dimensional objects. Computer simulations of spatial memory are summarized, and spatial memory is compared with other models of mental imagery.

Tracking modelled objects using binocular images

Abstract: This paper is concerned with the problem of tracking modelled objects from a time-ordered sequence of binocular images. Objects of interest are those on which four typical points can be consistently distinguished. The basic assumption is that we are given a model of the structure of these four points. The model is described in terms of the internal orientation of the structure and the distance between each pair of its points. This study addresses the problem of uniqueness of position of a binocularly viewed object.

Oblique magnetic resonance imaging of normal structures.

Abstract: The direct acquisition of sectional images in any desired plane is an inherent advantage of magnetic resonance imaging (MRI) over computed tomography (CT). Because of the orthogonal arrangement of the three gradient coils, most MRI systems are capable of obtaining images in standard axial, coronal, and sagittal orientation. Images of oblique planes that are rotated around one of the three standard orthogonal axes can be generated without hardware modification by simultaneous application of two orthogonal gradient fields during the three phases (slice selection, phase encoding, and signal read-out) of Fourier imaging [1]. Such slices may be useful in evaluating certain anatomic structures, organs, and lesions with oblique topographic orientation. We describe a method of generating MR images in oblique planes by a simple modification of an existing spin-echo pulse sequence program and assess its use in demonstrating various normal anatomic structures.

Parallel/Pipelined processor dedicated to visual recognition

Abstract: A parallel/pipelined processor has been developed for visual object recognition. It detects the position and orientation of the top workpiece in case workpieces are overlapping. The processor consists of a real-time edge detector and a high-speed image correlator. The real-time edge detector detects contours of workpieces at the video rate of a solid-state TV camera. It is relatively insensitive to changes of ambient light through the use of a logarithmic Sobel operator instead of a standard Sobel operator. The high-speed image correlator detects the position and orientation of the top workpiece which has a complete contour without any hidden portion. Parallel and pipeline concepts were applied to make the image correlator carry out more than 100 million pixel-level operations per second.

Laser imaging system and method for imposing pages for printing

Abstract: Laser imaging system and method for imaging a plurality of printed pages on an output medium in positions and orientations corresponding to an imposition format. Different areas of the medium are scanned to form the images for different pages with the beam traveling and being modulated to provide the proper orientation and position for each page.

A Multisensor Robotic Locating System And The Camera Calibration Problem

Abstract: A multisensor, microprocessor-controlled robotic locating system (RLS) is being devel-oped in our machine intelligence laboratory. A video camera, laser illuminator, optical angle sensors, and ultrasonics are the primary sensor components. Software is being de-veloped on a personal computer that has been augmented with video acquisition and high-speed signal processing boards. Real-time (less than 1 second) algorithms are being implemented that exploit both natural and artificial patterns. Artificial patterns are introduced by planting light-emitting diodes (LED) and reflective materials in the envi-ronment. Projecting light patterns is also part of the design. Using control points to determine camera position and orientation is a particularly interesting problem because of its apparent simplicity. Several algorithms for calibrat-ing a camera using control points are discussed in detail. The use of four control points in a rectangular configuration is especially detailed. A review of various approaches to camera calibration is included. The methods pre-sented are from the literature and work performed by the authors. These different ap-proaches provide insight into the nature of the problems. Closed form solutions are emphasized.

Robot Guidance Using A Morphological Vision Algorithm

Abstract: An algorithm has been developed to guide a robot by identifying the orientation of a randomly-acquired part held in the robot's gripper. A program implementing this algorithm is being used to demonstrate the feasibility of part-independent robotic bin picking*. The project task was to extract unmodified industrial parts from a compartmentalized tray and position them on a fixture. The parts are singulated in the compartments but are positionally and rotationally unconstrained. The part is acquired based upon three-dimensional image data which is processed by a 3D morphological algorithm described in [1]. The vision algorithm discussed here inspects the parts, determines their orientation and calculates the robot trajectory to a keyed housing with which the part must be mated. When parts are extracted during a bin picking operation their position and orientation are affected by many factors, such as gripper insertion-induced motion, interference with container side walls during extraction, slippage due to gravity and vibration during robot motions. The loss of the known position and orientation of the part in the robot gripper makes accurate fixturing impossible. Our solution to this problem was to redetermine the orientation of the part after acquisition. This paper describes the application in detail and discusses the problems encountered in robot acquisition of unconstrained parts. Next, the physical setup and image acquisition system, including lighting and optical components, are discussed. The principles of morphological (shape-based) image processing are presented, followed by a description of the interactive algorithm development process which was used for this project. The algorithm is illustrated step by step with a series of diagrams showing the effects of the transformations applied to the data. The algorithms were run on ERIM' s new fourth generation hybrid image processing architecture, the Cyto-HSS, which is described in detail in [2], and the performance is compared to the same programs executed on a general-purpose mid-sized computer.

Method and apparatus for rotating binary images

Abstract: A method and apparatus for converting an image in run representation form into a raster image which is rotated by some multiple of 90° from the orientation of the original image is disclosed wherein the original image data which is stored in run end or run length form may be divided and stored in discontiguous blocks. In implementing a 90° rotation. the image data is conceptually divided into vertical strips, each of which is independently rotated to create a horizonatl strip of the output image. The rotation process is carned out by firstly converting the run representation image data to raster form, dividing the data in each row among a number of intermediate buffers, each of which contains the data from one vertical stnp of the original image. The contents of each buffer are rotated and rearranged in an available buffer to form a horizontal stnp of the rotated image ready for raster readout Similarly, a convenient method of rotating the input image 180° is also described wherein the original image is read in run representation form a row at a time and the rows are converted to raster form and placed in storage in reverse order, with the order of the bits in each row also reversed.

Method and apparatus for use in measurement of the position of a line or edge of an object

Abstract: In a digitized picture, the orientation of the line is made nearly, but not exactly, parallel to a coordinate axis. Statistical analysis of the grid points or of the lattice points forming the line, preferably the former, gives the position and orientation of the line with high accuracy. Repeated measurements after small displacements of the line allows further improvement of the accuracy. Rectangular objects can be measured by taking differences between positions of opposite edges. The method can be extended to deal with curved lines, areas or the detection and measurement of edge or line features such as angles or properties of arcs. Measurement apparatus for practicing the method is also disclosed.

Discrimination of Higher-Order Textures

Abstract: Arrays of figural elements differing in certain features (‘textons’) may be visually segregated to yield the impression of a global figure of different texture. This fact was used to construct texture patterns of a higher level of complexity. In microstructure, these patterns reveal regular arrays of distinguishable figural elements, the segregation of which can be predicted from previous studies of human texture sensitivity. In macrostructure, clusters of such elements form new figural elements which, when repeated over space, themselves give the impression of texture at a perceptually higher level. Discrimination of such macrostructure textures was found to place similar restrictions on the form of figural elements as those of texture discrimination at the microstructure level.

Interactive Manipulation Of Three-Dimensional Data Via A Two-Dimensional Display Device

Abstract: The medical motivation for interactive manipulation of 3D data via a 2D display device is presented. Four specific topics are described: (i) interactive orientation specification, (ii) 3D83, a program currently being used in clinical practice, (iii) directed-contour-based display and manipulation, and (iv) binary-array-based display and manipulation. Timings are reported for medical exam-ples. Advantages and disadvantages of the various approaches are discussed.