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AN INTERPOLATION METHOD 
FOR CONTINENTAL DEM GENERATION 
USING SMALL SCALE CONTOUR MAPS 
Masataka TAKAGI and Ryosuke SHIBASAKI 
Institute of Industrial Science, 
The University of Tokyo. 
7-22, Roppongi, Minato-ku, Tokyo 106, JAPAN 
E-mail mural1@shunji.iis.u-tokyo.ac.jp 
Tel. +81-3-3402-6231 
Fax. +81-3-3479-2762 
Commission IV, Working Group 4 
Keywords: GIS, Geography, DEM/DTM, Interpolation, Contour line, Buffering 
Abstract: 
A continental DEM (Digital Elevation Model) is indispensable to solve global environmental 
problems. For continental DEM generation, an interpolation method using contour map becomes very 
helpful. We developed new reliable interpolation method which based on an intermediate contour line 
derivation. The intermediate contour line can be drawn by using a buffering method. The buffering is a 
very popular technique in GIS (Geographic Information System), which can be calculated distance from 
any points, vectors or polygons. So, it can apply to intermediate contour line derivation 
This paper presents a methodology of buffering method. And the results were compared with 
existing methods. Items for comparison are elevation, inclination, aspect, stream pattern and slope 
stability. The developed method gave the best results in all items. 
A relationship between a contour interval and an accuracy of generated DEM was concluded. The 
results showed a ratio of pixels of contour line in the whole raster map image must be more than 20%. 
  
1. INTRODUCTION 
A continental DEM (Digital Elevation 
Model) is indispensable to solve global 
environmental problems. NGDC, NOAA offers 
global land one-km base elevation (GLOBE). Its 
current version 0.1 is covering about 60% of the 
Earth's land surface. So, we must generate DEM 
ourselves sometime. 
Nowadays, there are many methods of DEM 
generation such as a stereo-matching from aerial 
photograph or satellite image, an interferemetry 
from stereo SAR data and an interpolation of 
topographic maps. For regional DEM or continental 
DEM generation, the interpolation method using a 
small scale contour map becomes very helpful. 
However, almost existing methods of the 
interpolation are intended for a large scale contour 
map. A mall scale contour maps have some 
  
  
  
  
Figure 1 Contour line map 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996