The roster model is an array-theoretic alternative to the set-theoretic relational model for handling tabular data. The roster model and its operations are extended here to incorporate fuzzy data modeling and manipula...
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ISBN:
(纸本)0818608439
The roster model is an array-theoretic alternative to the set-theoretic relational model for handling tabular data. The roster model and its operations are extended here to incorporate fuzzy data modeling and manipulation using possibility theory. The results is a fuzzy roster model, in which two levels of uncertainty are represented: the uncertainty in the data itself and the uncertainty in the truth value of the data. Fuzzy projections, selections, and joinings in the model are illustrated with the use of examples. The original roster model and the fuzzy roster model are implemented in the Nested interactive Array Language (NIAL) and are running on a Unix-based SUN-3 Workstation.
A parallel algorithm for the rasterization of polygons is presented that is suited for 3D Z-buffered graphics implementations. The algorithm represents each edge of a polygon by a linear edge function that has a value...
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A parallel algorithm for the rasterization of polygons is presented that is suited for 3D Z-buffered graphics implementations. The algorithm represents each edge of a polygon by a linear edge function that has a value greater than zero on one side of the edge and less than zero on the opposite side. The value of the function can be interpolated with hardware similar to hardware required to interpolate color and Z pixel values. The edge function of adjacent pixels may be easily computed in parallel. The coefficients of the 'Edge function' can be computed from floating point endpoints in such a way that sub-pixel precision of the endpoints can be retained.
The theory and implementation for a computer animation system to model a general class of three dimensional dynamic processes for arbitrary rigid bodies is presented. The simulation of the dynamic interaction among ri...
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The theory and implementation for a computer animation system to model a general class of three dimensional dynamic processes for arbitrary rigid bodies is presented. The simulation of the dynamic interaction among rigid bodies takes into account various physical characteristics such as elasticity, friction, mass, and moment of inertia to produce rolling and sliding contacts. If a set of bodies is statically unstable, the system dynamically drives it toward a stable configuration while obeying the geometric constraints of the system including general non-holonomic constraints. The system provides a physical environment with which objects animated using more traditional techniques can interact. The degree of interaction is controlled by the animator. A computationally efficient method to merge kinematics and dynamics for articulated rigid bodies to produce realistic motion is presented.
This paper presents rendering techniques that use volumes as the basic geometric primitives. It defines data structures composed of numerous subvolumes, in excess of 100,000. Over each subvolume, a scalar field descri...
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This paper presents rendering techniques that use volumes as the basic geometric primitives. It defines data structures composed of numerous subvolumes, in excess of 100,000. Over each subvolume, a scalar field describes the variation of some physical quantity. The two rendering methods described assume a trilinear variation of this scalar field within each volume element, unlike voxel-based techniques that assume a constant value for each subvolume. The result is a higher order approximation of the structures within the volume. Solid texture mapping, atmospheric attenuation, and transfer functions relating the dynamic range of the scalar field to color and opacity are used to isolate important data features. The result is a new method for the visualization of three-dimensional data resulting from numerical simulations and observations of natural phenomena. This method continuously covers the gap between surface-based and voxel-based techniques.
As newer and more sophisticated imagery collection systems rapidly increase the volume of imagery requiring thorough exploitation, the need for imagery analysts to acquire and maintain expertise increases accordingly....
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Graphical search is a technique for finding all instances of a graphical pattern in a synthetic picture in which objects are regions bounded by lines and curves. The pattern may describe shape, color and other propert...
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Graphical search is a technique for finding all instances of a graphical pattern in a synthetic picture in which objects are regions bounded by lines and curves. The pattern may describe shape, color and other properties. Matched objects may be allowed to differ from the pattern in rotation and scale or may differ in shape by a specified tolerance. Graphical replace is a technique for replacing the shape, color, or other properties of matched objects with new properties described in a replacement pattern. Combined, the two techniques are similar to textual search and replace in text editors. Graphical search and replace can be used to make global changes to illustrations with repetitive patterns, independent of the means used to make those patterns. It can also be used to create a class of iterative or recursive shapes that can be specified by replacement rules.
Symbolic manipulation is commonly used in theoretical physics. Compilers for language like REDUCE are usually large and thus suited for mainframes only. The need for simple manipulation of polynomials in many variable...
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Symbolic manipulation is commonly used in theoretical physics. Compilers for language like REDUCE are usually large and thus suited for mainframes only. The need for simple manipulation of polynomials in many variables using easily accessible techniques led the first author to design and implement a language FORTRAN/P which is standard FORTRAN with two new types VARIABLE and POLYNOM. Nowadays micros have changed the situation and a completely new system POLYMAN for interactive polynomial handling has been developed.
Refinement is usually advocated as a means of gaining finer control over a spline curve or surface during editing. For curves, refinement is a local process. It permits the change of control vertices and subsequent ed...
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Refinement is usually advocated as a means of gaining finer control over a spline curve or surface during editing. For curves, refinement is a local process. It permits the change of control vertices and subsequent editing of fine detail in one region of the curve while leaving control vertices in other regions unaffected. For tensor-product surfaces, however, refinement is not local in the sense that it causes control vertices far from a region of interest to change as well as changing the control vertices that influence the region. However, with some care and understanding it is possible to restrict the influence of refinement to the locality at which an editing effect is desired. We present a method of localizing the effect of refinement through the use of overlays, which are hierarchically controlled subdivisions. We also introduce two editing techniques that are effective when using overlays: one is direct surface manipulation through the use of edit points and the other is offset referencing of control vertices.
The display of three-dimensional medical data is becoming more common, but current display hardware and image rendering algorithms do not generally allow real-time interaction with the image by the user. Real-time int...
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Certain Catmull-Rom splines interpolate their control vertices and share many properties such as affine invariance global smoothness and local control with B-spline curves;they are therefore of possible interest to co...
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Certain Catmull-Rom splines interpolate their control vertices and share many properties such as affine invariance global smoothness and local control with B-spline curves;they are therefore of possible interest to computer aided design. It is shown that another property a class of Catmull-Rom splines shares with B-spline curves is that both schemes possess a simple recursive evaluation algorithm. The Catmull-Rom evaluation algorithm is constructed by combining the de Boor algorithm for evaluating B-spline curves with Neville's algorithm for evaluating Lagrange polynomials. The recursive evaluation algorithm for Catmull-Rom curves allows rapid evaluation of these curves by pipelining with specially designed hardware. It facilitates the development of new, related curve schemes which may have useful shape parameters for altering the shape of the curve without moving the control vertices. It may also be used for constructing transformations to Besier and B-spline form.
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