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Title: MATHEMATICAL SURFACE APPROXIMATION OF THE TERRAIN
Accession Number: 00229900
Record Type: Component
Abstract: A PRELIMINARY STUDY HAS BEEN MADE TO DETERMINE THE FEASIBILITY OF APPROXIMATING TERRAIN WITH A MATHEMATICAL SURFACE SO AS TO OBVIATE CROSS-SECTIONAL METHODS IN HIGHWAY ENGINEERING. THE ADVANTAGES AND DISADVANTAGES OF CROSS-SECTIONS ARE DISCUSSED IN THE LIGHT OF THE ADVANTAGES AND EXISTING PROBLEMS IN THE NUMERIC-SURFACE APPROACH. A NUMERIC GROUND IMAGE (NGI) SYSTEM IS ANALYZED AND DESIGNED: THE VARIOUS SUBSYSTEMS FOR COMPUTER THROUGHPUT ARE DESCRIBED. APPLICATIONS OF THE NGI TO COMPUTER-AIDED DESIGN (CONTOUR MAPS AND PERSPECTIVE VIEWS) AND TO CALCULATION OF EARTHWORK QUANTITIES ARE ILLUSTRATED. IT IS SHOWN HOW THE NGI METHOD CAN ELIMINATE SOME TERRAIN REPRESENTATION PROBLEMS ASSOCIATED WITH THE CROSS-SECTIONAL APPROACH, E.G., OBTAINING A NEW SET OF SECTIONS WHEN THE HORIZONTAL ALIGNMENT OF A ROADWAY IS SHIFTED. THIS IS UNNECESSARY WITH THE NUMERIC SURFACE APPROACH, BECAUSE IT IS NOT DIRECTLY REFERENCED TO ANY SPECIFIC ALIGNMENT. THE NGI ELEVATION SUBSYSTEM COULD NOT, WITHIN THE LIMITS OF THE STUDY, BE EXERCISED ON TERRAIN WITH DISCONTINUITIES, WHICH MAY BE A SOURCE OF INACCURACY; ADDITIONAL ERROR MAY RESULT FROM THE ASSUMPTION THAT THE EARTH'S SHAPE IS PARABOLIC. SIX AREAS THAT REQUIRE FURTHER ATTENTION ARE DISCUSSED.
Supplemental Notes: Paper sponsored by Committee on Photogrammetry and Aerial Surveys and presented at the 49th Annual Meeting. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
Monograph Title: Monograph Accession #: 01410258
Authors: Maxwell, Donald APagination: pp 16-29
Publication Date: 1970
Serial: Media Type: Digital/other
Features: Figures
(10)
; References
(13)
TRT Terms: Subject Areas: Design; Geotechnology; Highways; Pavements
Files: TRIS, TRB
Created Date: Dec 28 1970 12:00AM
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