5 results
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2. A Characterization of Ten Hidden-Surface Algorithms.
- Author
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Sutherland, Ivan E., Sproull, Robert F., and Schumacker, Robert A.
- Subjects
- *
SORTING (Electronic computers) , *COMPUTERS , *ALGORITHMS , *COHERENCE (Optics) , *TELEVISION scanning , *PICTURES , *OBJECT-oriented methods (Computer science) , *DATA structures , *OPTICAL computer equipment - Abstract
This paper discusses the hidden-surface problem from tile point of view of sorting. The various surfaces of an object to be shown in hidden-surface or hidden-line form must be sorted to find out which ones are visible at various places on the screen. Surfaces may be sorted by lateral position in the picture (X I'), by depth (Z), or by other criteria. The paper shows that the order of sorting and the types of sorting used form differences among the existing hidden-surface algorithms. To reduce the work of sorting, each algorithm capitalizes on some coherence property of the objects represented. ‘Scan-line coherence,’ the fact that one TV scan line of output is likely to be nearly the same as the previous TV scan line, is one commonly used kind of coherence. ‘Frame coherence,’ the fact that the entire picture does not change very much between successive frames of a motion picture can be very helpful if it is applicable. By systematically looking for additional kinds of coherence and untried sorting orders and sorting types, the paper is able to suggest two promising new approaches to the hidden-surface problem. The first, a combination of three existing algorithms, is promising because it would capitalize on both frame and scan-line coherence. The second new approach would sort in the order Y, Z, X, … the only sorting order for which an existing algorithm could not be found. [ABSTRACT FROM AUTHOR]
- Published
- 1974
- Full Text
- View/download PDF
3. Sorting.
- Author
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Martin, William A.
- Subjects
- *
SORTING (Electronic computers) , *COMPUTER algorithms , *COMPUTER programming , *ELECTRONIC data processing , *ALGORITHMS - Abstract
The bibliography appearing at the end of this article lists 37 sorting algorithms and 100 books and papers on sorting published in the last 20 years. The basic ideas presented here have been abstracted from this body of work, and the best algorithms known are given as examples. As the algorithms are explained, references to related algorithms and mathematical or experimental analyses are given. Suggestions are then made for choosing the algorithm best suited to a given situation. [ABSTRACT FROM AUTHOR]
- Published
- 1971
- Full Text
- View/download PDF
4. Optimizing the Polyphase Sort.
- Author
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Shell, Donald L.
- Subjects
ALGORITHMS ,SORTING (Electronic computers) - Abstract
Examines various dispersion algorithms for the polyphase sorting procedure. Optimum algorithm based on minimizing total number of unit strings read; Repetition operator.
- Published
- 1971
- Full Text
- View/download PDF
5. Optimum Merging from Mass Storage.
- Author
-
Black, Neville A.
- Subjects
ALGORITHMS ,INFORMATION retrieval ,DOCUMENTATION ,SORTING (Electronic computers) ,MOTHERBOARDS ,ALGEBRA - Abstract
An algorithm is displayed which yields the merge orders such that the total read time, defined to be the sum of seek time plus data-transfer time, is minimized for a sort using mass storage. The analysis is parameterized in terms of the ratio of seek time to the time it takes to fill available core with records, and the file size in units of core lengths; and thus it can be applied to any conventional CPU mass storage combination. An explicit formula for total read time is derived, in terms of the parameters, which correlates very well with the total read time calculated using the optimum merge orders yielded by the algorithm. The formula involves the roots of a simple transcendental equation. A short table of these roots is included. Numerical results are graphically displayed for a wide range of the parameters. It is found that the normalized read time for optimum merging on a given hardware configuration is proportional to the file length times the logarithm of the file length. [ABSTRACT FROM AUTHOR]
- Published
- 1970
- Full Text
- View/download PDF
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