Can Digital Terrain Data Cut Route Selection Time?

by Robert F. Turner, (M.ASCE), Unit Supervisor; U.S. National Forest Service, Mapping Unit,

Serial Information: Civil Engineering—ASCE, 1984, Vol. 54, Issue 2, Pg. 50-52

Document Type: Feature article


The use of photogrammetry in the collection of digital terrain and the use of a computer to process data is not being used to its fullest. Use of these two tools together increases access to vast amounts of information, improves the ability to manipulate data and displays it in recognizable form. Use of photogrammetry and microprocessing equipment is replacing traditional methods of reconnaissance as a means of collecting and processing preliminary survey data. Photogrammetry plus computers provide the modern engineer with data on project alternatives that traditional methods would be unable to supply. A single-lane road running through a Northern Idaho national forest required upgrading. Using traditional ground surveying methods for the forest, which was covered with tall trees would have been difficult. Digital terrain data helped compare alternative routes. Collecting the digital terrain data began with the use of stereo pairs of aerial photographs, which were viewed through a stereoplotter. Computer-stored terrain data served as a data bank for producing contour plots, perspective views, slope and aspect data, aerial photo overlays and input for design programs. Modern microprocessing capabilities enabled the reconnaissance crew to eliminate three of the five alternatives, the cost of which was in excess of project needs. Two locations showed potential for further field location and analysis.

Subject Headings: Terrain

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