Digital Elevation Model (DEM) derived from survey data is accurate but it is very expensive and time-consuming. In
recent years, remote sensing techniques including Synthetic Apenture Radar Interferometry (InSAR) had been developed
as a powerful method to derive high precision DEM, especially in mountainous or deep forest areas. The purpose of this
paper is to illustrate the principle of InSAR and show the result of a case study in Gejiu city, Yunnan province, China.
The accuracy of DEM derived from InSAR (abbreviation as InSAR-DEM) is also evaluated by comparing it with DEM
generated from topographic map at the scale of 1:50000 (abbreviation as TOP-DEM). The result shows that: (1)The
general precision of the whole selected area acquired by subtracting InSAR-DEM from TOP-DEM is that the maximum,
the minimum, the RMSE, and the mean of difference of the two DEMs are 203m, -188m, 26.9m and 5.7m respectively.
(2)The topographic trend represented by the two DEMs is coincident, even though TOP-DEM is finer than InSAR-DEM,
especial at the valley. (3) Contour maps with the interval of 100m and 50m converted from InSAR-DEM and TOP-DEM
respectively show accordant relief trend. Contour from TOP-DEM is smoother than that of from InSAR-DEM, while
Contour from InSAR-DEM has more islands than that of from TOP-DEM.(4) Coherence has great influence on the
precision of InSAR-DEM, the precision of low-coherence area approaches 100 m while that of high-coherence area can
up to m level. (5) The relief trend of 6 profiles represented by InSAR-DEM and TOP-DEM is accordant with tiny
difference in partial minutiae. InSAR-DEM displays hypsographies at relative flat areas including surface of water,
which reflects the influence of flat earth on InSAR to a certain extent.