Showing papers on "Motion estimation published in 1979"

The Interpretation of Structure from Motion

Abstract: The interpretation of structure from motion is examined from a computional point of view. The question addressed is how the three dimensional structure and motion of objects can be inferred from the two dimensional transformations of their projected images when no three dimensional information is conveyed by the individual projections. The following scheme is proposed: (i) divide the image into groups of four elements each; (ii) test each group for a rigid interpretation; (iii) combine the results obtained in (ii). It is shown that this scheme will correctly decompose scenes containing arbitrary rigid objects in motion, recovering their three dimensional structure and motion. The analysis is based primarily on the 'structure from motion' theorem which states that the structure of four non-coplanar points is recoverable from three orthographic projections. The interpretation scheme is extended to cover perspective projections, and its psychological relevance is discussed.

Image Analysis of Human Motion Using Constraint Propagation

Abstract: A system capable of analyzing image sequences of human motion is described. The system is structured as a ·feedback loop between high and low levels: predictions are made at the semantic level, and verifications are sought at the image level. The domain of human motion lends itself to a model-driven analysis, and the system includes a detailed model of the human body. All information extracted from the image is interpreted through a constraint network based on the structure of the human model. A constraint propagation operator is defined and its theoretical,properties developed. An implementation of this operator is described, and results of the analysis system for a short image sequence are presented.

Motion estimation and encoding of video signals in the transform domain

Abstract: Video signals are encoded (FIG. 5) using motion compensated prediction which operates on a transform domain representation of the signal. The displacement estimate used for compensation is recursively updated, so that a feedback path exists between the output (205) of the displacement calculator and one of its output (209). The update term is also computed in the transform domain. A decoder (FIG. 6) uses the same prediction technique to recover the original picture.

A target tracker using spatially distributed infrared measurements

Abstract: An extended Kalman filter algorithm is designed to track a point source target in an open-loop tracking problem, using outputs from a forward-looking infrared (FLIR) sensor as measurements. The filter separately estimates the translational position changes of the target in the FLIR field of view due to two effects: actual target motion and apparent motion caused by atmospheric turbulence. A Monte Carlo analysis is conducted to determine the performance of the filter as a function of signal-to-noise ratio, target spot size, the ratio of rms target motion to rms atmospheric jitter, target correlation times, and mismatches between the true target spot size and the size assumed by the filter. The performance of the extended Kalman filter is compared to the performance of an existing correlation tracker under identical conditions. A one sigma tracking error of 0.2 and 0.8 picture elements is obtained with signal-to-noise ratios of 20:1 and 1:1, respectively. No degradation in performance is observed when the spot size is decreased or when the target correlation time is increased over a limited range, when filter parameters are adjusted to reflect this knowledge. Sensitivity analysis shows that the filter is robust to minor changes in target intensity spot size.

Transform domain motion estimation

Abstract: This paper introduces an algorithm for estimating the displacement of moving objects in a television scene from spatial transform coefficients of successive frames. The algorithm works recursively in such a way that the displacement estimates are updated from coefficient to coefficient. A promising application of this algorithm is in motion-compensated interframe hybrid transform- dpcm image coding. We give a statistical analysis of the transform domain displacement estimation algorithm and prove its convergence under certain realistic conditions. An analytical derivation is presented that gives sufficient conditions for the rate of convergence of the algorithm to be independent of the transform type. This result is supported by a number of simulation examples using Hadamard, Haar, and Slant transforms. We also describe an extension of the algorithm that adaptively updates displacement estimation according to the local features of the moving objects. Simulation results demonstrate that the adaptive displacement estimation algorithm has good convergence properties in estimating displacement even for very noisy images.

Stereoscopic motion picture-circular to linear scan translator-method and apparatus

Abstract: My invention relates to photographing scenes with a standard motion picture camera in which there is a relative motion between the scene and camera with the purpose of stereoscopic viewing of the motion picture without the need for viewing aids at the eye. The system is compatible with scenes photographed without this relative motion but the reproduction is flat. The film (or other appropriate media) is arrayed in a vertical plane and constrained to move horizontally around a segment of a circle of radius 2R. At the center of the film circle is a film motion compensator which can be a multi-faceted mirror drum of radius R. The film is rapidly scanned about the center of this circle by a scan projector. Projection optics on the projector, project the sequential film frames onto a relatively large circular cylindrical screen having its vertical axis coincident with the projector axis. The screen is constructed of small vertical segments which are corrugated to cause the incident projection rays to vertically scatter and horizontally reflect such that all rays for a given projection location on the projection circle, will converge to a vertical aerial exit slit. The exit slit moves linearly while the projector moves in a circular arc about a fixed lamp. If the film and motion compensator are in locked motion, stereoscopic motion pictures can be observed by a number of people at the same time without any form of visual aid at their eyes.

A score for correct data association in multi-target tracking

Abstract: In the real-world multi-target tracking problem, there exists the possibility for many things to go wrong. Typical problems which arise include: too few tracks are formed; too many tracks are formed (false tracks); and inaccurate position, course, and speed estimates are reported. The above difficulties are often the result of incorrect allocation of data to individual tracks. Algorithms, while estimating the motion of a given target, inadvertently mix in clutter and/or measurements from another target. In order for correct allocation of data to a given track to be made, one must have an effective scoring formula; that is, some means of determining how likely a given assignment of data is. To be effective, a scoring formula must produce (on the average) a better score for correct assignments than for incorrect assignments. Information useful in the scoring process includes a priori intelligence data (such as initial target locations), models of target motion, models of the transmission channel, and expected moments of clutter for the sensor gain setting being used. Basically, the score is derived from the residuals which come out of the processing of a batch of data with the extended Kalman filter. This is used to evaluate the likelihood of potential tracks. Although the "likelihood" has an intuitive meaning, the term is used here to mean the probability density function p(?) of the track ?. The expected cost of a given assignment is derived with the theory of extremals being used to obtain the expected cost of adding a clutter point in a track. The resulting expected cost is then shown to behave in a quantitative fashion and this can be visualized from a geometric viewpoint.