Research on the optimal picket sampling interval in automated digital terrain model creation by using digital photogrammetry

Abstract

In the method of creating digital terrain model (DTM) by using digital photogrammetry, the picket sampling interval (PSI) plays an important role since it strongly influences on the production effectiveness and on the accuracy of created DTMs. The optimal value of PSI must be balanced between requirements of effectiveness and of accuracy. This research is focused on the influence of PSI on root mean square error (RMSE) of created DTM and on the number of error pickets (caused by limitation of image matching technique) that must be checked and corrected manually. Based on the results obtained in four experimental areas of Vietnam (Co Loa, Duong Lam, Ba Vi, and Lang Son), the paper has proposed an empirical equation for choosing optimal PSI: PSI = k P×Ma , where P is the scan resolution (μm); a M is the denominator of airphoto scale; k is a coefficient depending on the characteristics of topography.