SRTM‐assisted block adjustment for stereo pushbroom imagery

Abstract

AbstractThis paper proposes a stereo‐image block‐adjustment algorithm without ground control points (GCPs) by adopting a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) as a height assistant. Using dense, evenly distributed tie points on images used in the block adjustment, the initial height values of tie points are derived directly from the SRTM DEM. In the subsequent block‐adjustment iterative computation, the height correction value for tie points is rigorously restricted by the SRTM DEM elevation. A total of 509 ZY‐3 satellite stereo‐images across 190 000 km2 of China's Hubei Province were used for this block‐adjustment experiment. The results show that the vertical root mean square errors (RMSEs) are improved from 7·2 to 2·3 m without GCPs, while the RMSEs in flat and mountainous terrain are improved to 1·5 and 2·8 m, respectively, fulfilling the vertical accuracy requirement of China's 1:25 000 scale mapping.