Accuracy, reliability, and depuration of SPOT HRV and Terra ASTER digital elevation models

The aim of this communication is to study the accuracy and reliability of digital elevation models (DEMs) generated from two different satellite sources [the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)] and [the Systeme P'our l'Observation de la Terre (SPOT) High Resolution Visible (HRV)] stereoscopic images), using three different photogrammetric softwares. The main reason of the study is the heterogeneity and absence of agreement found in previous research concerning several significant aspects of DEM generation methods. A set of 91 DEMs were generated from SPOT data and 55 DEMs from ASTER data. Error control was performed with 315 check points determined by differential global positioning systems. Results of Terra ASTER DEMs show that elevation RMSE (root mean square error) equals 13.0 m. The corresponding RMSE value for SPOT HRV DEM is 7.3 m. In both cases, the error is less than the pixel size. Furthermore, this communication proposes a technique to improve DEM structure, based on an objective criterion to cleanse redundancy in DEMs without a significant loss of accuracy. This criterion is based on removing all points with a correlation value below a threshold value.