Geostatistical Approach for Computing Absolute Vertical Accuracy of Digital Terrain Models

Digital Terrain Models (DTMs) are widely and intensively used as a computerized mapping and modeling infrastructure representing our environment. There exist many different types of wide-coverage DTMs generated by various acquisition and production techniques, which differ significantly in terms of geometric attributes and accuracy. In aspects of quality and accuracy most studies investigate relative accuracy relying solely on coordinate-based comparison approaches that ignore the local spatial discrepancies exist in the data. Our long-term goal aims at analyzing the absolute accuracy of such models based on hierarchical feature-based spatial registration, which relies on the represented topography and morphology, taking into account local spatial discrepancies exist. This registration is the preliminary stage of the quality analysis, where a relative DTM comparison is performed to determine the accuracy of the two models. This paper focuses on the second stage of the analysis applying the same mechanism on multiple DTMs to compute the absolute accuracy based on the fact that this solution system has a high level of redundancy. The suggested approach not only qualitatively computes posteriori absolute accuracies of DTMs, usually unknown, but also thoroughly analyzes the absolute accuracies of existing local trends. The methodology is carried out by developing an accuracy computation analysis using simultaneously multiple different independent wide-coverage DTMs that describe the same relief. A comparison mechanism is employed on DTM pairs using Least Squares Adjustment (LSA) process, in which absolute accuracies are computed based on theory of errors concepts. A simulation of four synthetic DTMs is presented and analyzed to validate the feasibility of the proposed approach.