Automated DEM extraction in digital aerial photogrammetry: precisions and validation for mass movement monitoring

Abstract

Automated procedures for photogrammetric image processing and Digital Elevation Models (DEM) extraction
yield high precision terrain models in a short time, reducing manual editing; their accuracy is strictly related to
image quality and terrain features. After an analysis of the performance of the Digital Photogrammetric Workstation
(DPW) 770 Helava, the paper compares DEMs derived from different surveys and registered in the same
reference system. In the case of stable area, the distribution of height residuals, their mean and standard deviation
values, indicate that the theoretical accuracy is achievable automatically when terrain is characterized by
regular morphology. Steep slopes, corrugated surfaces, vegetation and shadows can degrade results even if manual
editing procedures are applied. The comparison of multi-temporal DEMs on unstable areas allows the monitoring
of surface deformation and morphological changes.