RAPID DISPLAY OF DIGITAL ELEVATION MODELS
IN A MINI-COMPUTER ENVIRONMENT
Lawrence Kikuchi
Ph.D. Candidate
State University of New York at Buffalo
Geographic Information Systems Laboratory
415 Fronczak Hall - Amherst NY 14260
Jose Armando Guevara
Ph.D. Candidate - State University of New York at Buffalo
Assistant Professor of Computer Science
Universidad de Los Andes
Escuela Ingeniería de Sistemas - Dpto. Computación
Merida - Venezuela
David Mark
Assistant Professor of Geography
State University of New York at Buffalo
Geographic Information Systems Laboratory
415 Fronczak Hall - Amherst NY 14260
Duane F. Marble
Professor of Geography
Adjunct Professor of Computer Science
State University of New York at Buffalo
Geographic Information Systems Laboratory
415 Fronczak Hall - Amherst NY 14260
ABSTRACT
Digital Elevation Models (DEM) are digital representations
of the earth's surface. As with all systems which man
ipulate large volumes of data, the performance of the
algoriturns uepenus strongly on the efficient storage and
structuring of the data. DEM aata are often obtained or
generated as a uniform rectangular grid (URG) organized
either in profiles (scan lines) or patches.
This paper describes a DEM processing system for the quick
inspection and display of these digital elevation models.
Utilizing system specific binary blocked I/O, and a run
time, run-length algoritm, the system is able to produce
contour band maps, contours, anagrapliic contours, slope
gradient and aspect maps, and analytical hill-shading for
a variety of applications. The system is interactive,
being able to process a digital grid of 200,000 cells in
about two minutes on a Data General Eclipse S/130 mini
computer running under RDOS. Other features being incorp
orated into the system include the detection of pits,
peaks, passes, ridges, and ravines. The system can poten
tially handle any regular grid DEM's, but is currently
keyed to the U.S. Geological Survey's "7-1/2 minute Quad
rangle" series of digital data sets.
