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Showing papers on "Centroid published in 1982"


Journal ArticleDOI
TL;DR: The approach is a generalization of a recently developed speech coding technique called speech coding by vector quantization based on the minimization of cross-entropy, and can be viewed as a refinement of a general classification method due to Kullback.
Abstract: This paper considers the problem of classifying an input vector of measurements by a nearest neighbor rule applied to a fixed set of vectors. The fixed vectors are sometimes called characteristic feature vectors, codewords, cluster centers, models, reproductions, etc. The nearest neighbor rule considered uses a non-Euclidean information-theoretic distortion measure that is not a metric, but that nevertheless leads to a classification method that is optimal in a well-defined sense and is also computationally attractive. Furthermore, the distortion measure results in a simple method of computing cluster centroids. Our approach is based on the minimization of cross-entropy (also called discrimination information, directed divergence, K-L number), and can be viewed as a refinement of a general classification method due to Kullback. The refinement exploits special properties of cross-entropy that hold when the probability densities involved happen to be minimum cross-entropy densities. The approach is a generalization of a recently developed speech coding technique called speech coding by vector quantization.

109 citations


Patent
29 Sep 1982
TL;DR: In this paper, a method and apparatus for determining the spatial coordinates of a workpiece including a precisely formed jig, a planar light source, an electronic imaging device adapted to view the intersection of the planar lights with the jig and the workpiece, a video digitizer for sampling and digitizing output signals from the imaging device and in particular reference pulse signals representative of said intersections, digital logic circuitry for algebraically summing video samples to determine the centroid or geometric mean of the reference pulses; and a computer for calculating calibration parameters based on knowledge of the form
Abstract: A method and apparatus for determining the spatial coordinates of a workpiece including: a precisely formed jig; a planar light source; an electronic imaging device adapted to view the intersection of the planar light with the jig and the workpiece; a video digitizer for sampling and digitizing output signals from the imaging device and in particular reference pulse signals representative of said intersections; digital logic circuitry for algebraically summing video samples to determine the centroid or geometric mean of the reference pulses; and a computer for calculating calibration parameters based on knowledge of the form of the jig and scans of the jig, and applying those calibration parameters to scans of the workpiece to calculate spatial coordinates of the workpiece. A method of determining the centroid of a sensed pulse signal including the steps of integrating the signal over a selected interval including the pulse by analog or digital means, integrating the result of the first integration in like manner and dividing result of the second integration by the result of the first integration.

84 citations


Patent
30 Sep 1982
TL;DR: In this paper, the boundary and centroid of a part are obtained from the optimal ternary data using the variance of the gray-level of the image and the separation degree of a histogram.
Abstract: An image processor which can accurately and promptly obtain information about a ventricle of a living body, such as the boundary diagram, the volume, the centroid movement view and a three-dimensional view. An X-ray projection of a part to be diagnosed is quantized. The boundary and centroid of the part are obtained from the optimal ternary data using the variance of the gray-level of the image and the separation degree of a histogram. The volume and three-dimensional view of the part are obtained from this data using the gray-level method.

39 citations


Patent
11 Jun 1982
TL;DR: In this article, the point of measurement with a coordinate system proper to an object image was used to obtain various kinds of information needed for the robot work to a subject of recognition which was shown with optional position and posture within a veiwfield.
Abstract: PURPOSE:To obtain various kinds of information needed for the robot work to a subject of recognition which is shown with optional position and posture within a veiwfield, by teaching the point of measurement with a coordinate system proper to an object image CONSTITUTION:A visual device for robot is provided with a picture input part 101, a teaching processing part 102 and a recognition processing part 103 When the teaching is selected by a switch SW, both parts 101 and 102 work Then parts 101 and 103 work when the recognition is selected A form data extracting part 7 of the part 103 gives features to a subject image by means of the coordinates of the contour point stored in a contour point coordinate memory (b) and then obtains the area, the circumference length, the ratio between area and circumference length, the number of holes, etc for example to store them in a teaching form data storage memory (c) A centroid calculating part 8 obtains the centroid G of the subject image from the contour point coordinates; and an inertial main axis inclination calculating part 9 obtains the inclination theta of the inertial main axis of the subject image from the contour point coordinates The contents of these centroid and inclination are stored in a coordinate conversion storage memory (d)

11 citations


Journal ArticleDOI
TL;DR: In this article, a new method of track fitting is described which exploits the digital aspects and which takes the correlations into account, which divides the parameter space into cells and the centroid of a cell is taken as the best estimate.

8 citations


Journal ArticleDOI
TL;DR: In this article, the authors established a chain of plane isometric subgroups, three series of plane normal subgroups and a technique for characterizing a geometric element by the minimal number of its invariant points under an isometry.

8 citations


Patent
18 Oct 1982
TL;DR: In this paper, the centroid of a beam of electromagnetic energy is detected by focusing the beam into a blur spot upon a focal plane, and the intensity of the output from each photodetector is then measured and the difference and sum of these measurements obtained.
Abstract: A device for detecting the centroid of a beam of electromagnetic energy is shown including means for focusing the beam into a blur spot upon a focal plane. Photodetectors located at the focal plane detect the centroid of the blur spot on either side of its nominal location. The intensity of the output from each photodetector is then measured and the difference and sum of these measurements obtained. By dividing the difference by the sum of the resultant signals, it is possible to produce an analog signal which represents the location of the blur spot centroid regardless of its amplitude. This arrangement has particular application in acousto-optic devices for measuring the frequency and direction of arrival of an incoming radio frequency wave.

4 citations


Proceedings ArticleDOI
30 Apr 1982
TL;DR: In this article, the image signal-to-noise ratio and statistical variance of image centroid estimates were derived for coherent heterodyne and homodyne laser radar images of extended diffuse targets.
Abstract: The image signal-to-noise ratio and statistical variance of image centroid estimates are derived for coherent heterodyne and homodyne laser radar images of extended diffuse targets. Both intensity and binary target images are studied. Binary image is shown generally to offer a more reliable estimate of the target centroid.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

1 citations