Relative DEM production from SPOT data without GCP

Abstract

This paper describes a method to produce a relative digital elevation model (DEM) from SPOT level 1A stereo pair or triplet images without the use of ground control points. The proposed method consists of 1. stereo matching by correlation, 2. calculation of the intersection point of pair or triplet viewing lines and 3. interpolation from random DEM to grid DEM. The emphasis is laid on how to restrict a search area for stereo matching using approximate epipolar constraint.

Relative error (standard deviation of error) of 80 by 50poinis DEM produced from stereo pair images with the convergence angle of 32° was found to be less than 30 m. Relative error from stereo triplet images was less than 26 m. The obtained relative errors suggest the potential of SPOT data to produce a relative DEM in the area where ground control points are not available.