A method is developed for the measurement of short-range visual motion in image sequences, making use of the motion of image features such as edges and points. Each feature generates a Gaussian activation profile in a...
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A method is developed for the measurement of short-range visual motion in image sequences, making use of the motion of image features such as edges and points. Each feature generates a Gaussian activation profile in a spatiotemporal neighborhood of specified scale around the feature itself; this profile is then convected with motion of the feature. The authors show that image velocity estimates can be obtained from such dynamic activation profiles using a modification of familiar gradient techniques. The resulting estimators can be formulated in terms of simple ratios of spatiotemporal filters (i.e. receptive fields) convolved with image feature maps. A family of activation profiles of varying scale must be utilized to cover a range of possible image velocities. They suggest a characteristic speed normalization of the estimate obtained from each filter in order to decide which estimate is to be accepted. They formulate the velocity estimators for dynamic edges in 1-D and 2-D image sequences, as well as that for dynamic feature points in 2-D image sequences.< >
This paper describes and evaluates the design of four virtual controllers for use in rotating three-dimensional objects using the mouse. Three of four of these controllers are "new" in that they extend tradi...
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This note describes a new data structure which records information and supports queries about elements that have been previously inserted and deleted. Both time and space parameters match those of Overmars (1981); the...
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This note describes a new data structure which records information and supports queries about elements that have been previously inserted and deleted. Both time and space parameters match those of Overmars (1981); the advantage to the structure described here is its simplicity.
Following the establishment of GKS as the first international standard for computergraphics, two new standards, GKS-3D and PHIGS, are emerging which cater for three-dimensional graphics. In order to display a 3-D obj...
Following the establishment of GKS as the first international standard for computergraphics, two new standards, GKS-3D and PHIGS, are emerging which cater for three-dimensional graphics. In order to display a 3-D object, a description of how it is to be viewed must be given. GKS-3D and PHIGS provide a viewing pipeline to generate the parallel or perspective view required. This paper describes in detail the functionality and an implementation of the GKS-3D/PHIGS viewing pipeline.
ROSE is an experimental database system for CAD/CAM applications that organizes a database into entries and relationships. The data model of ROSE is an extension of the relational model and the data manipulation langu...
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An assortment of algorithms, termed three-dimensional (3D) scan-conversion algorithms, is presented. These algorithms scan-convert 3D geometric objects into their discrete voxel-map representation within a Cubic Frame...
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This paper reports on an interactive system for manipulating a tensor-product B-spline approximation to field data for applications in which contours are of interest. The features of the system are: an interpolation t...
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Several different adaptive subdivision algorithms are developed for a set of Bézier triangle surfaces which generate piecewise planar approximations to the surfaces. They are called adaptive because they use more...
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Several different adaptive subdivision algorithms are developed for a set of Bézier triangle surfaces which generate piecewise planar approximations to the surfaces. They are called adaptive because they use more triangles in areas of greater curvature of the surfaces and so adapt to the local geometry of the surfaces. The approximation is guaranteed not to deviate from the true surface more than an arbitrarily specified tolerance. Due to the many different ways of subdividing Bézier triangles, a number of adaptive subdivision algorithms are possible. This paper develops, categorizes, and compares some of the plausible ones. The chief distinctions between the algorithms are the number triangles that are generated and their degree of uniformity (eg ‘equilateralness’). Minimizing the number of triangles generated is important for efficient processing on the approximation. However, very nonuniform triangles, which can aid in this minimization, can also cause severe numerical problems.
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