Accuracy Analysis of Digital Elevation Model Relating to Spatial Resolution and Terrain Slope by Bilinear Interpolation

This study investigates the accuracy analysis of the digital elevation model (DEM) with respect to the following two major factors that strongly affect the interpolated accuracy: (1) spatial resolution of a DEM and (2) terrain slope. Unlike existing studies based mainly on a simulation approach, this research first provides an analytical approach in order to build the relationship between the interpolated DEM accuracy and its influencing factors. The bi-linear interpolation model was adopted to produce this analytic model formalized as inequalities. Then, our analytic models were verified and further rectified by means of experimental studies in order to derive a practical formula for estimating the DEM accuracy together with an optimization model for calculating the required resolution when a prescribed upper bound to the DEM accuracy is given. Moreover, this analytic approach can cope with either a grid-based DEM or a randomly scattered scenario whose efficacies have been validated by the experiments using both synthetic and realistic data sets. In particular, these findings first establish the rules for directly correlating the horizontal resolution of DEM data with vertical accuracy.