The Stereomapping System mechanizes the operation of a Kelsh plotter to automatically produce contour data and orthophotos. It utilizes a Nipkow disc to scan the stereo image and makes appropri-ATE HEIGHT CHANGES TO KEEP THE SCANNING SURFACE AT THE ELEVATION OF THE TERRAIN MODEL. The detailed terrain data obtained from the scan is used to recreate the image element in proper position for orthophoto production; the altitude information is obtained by reporting the height of the scanning disc. The orthophoto and altitude data are recorded photographically in a printout subassembly. The system analysis, electronic design and mechanical design did not reveal any serious problems. The mechanical system is conventional, with carriage supports consisting of ball-nut bushings and tubular ways. The orthophoto and drop-line chart are produced photographically, the latter by a ''print-out'' of three gray tones whose boundaries define the desired contour intervals. (Author).