Effectiveness of Geometric Quality Control Using a Distance Evaluation Applied to an Ifsar Dem

Abstract A new method, the Perpendicular Distance Estimation Method (PDEM), to estimate the precision of a Digital Elevation Model (DEM) with its effectiveness in the evaluation of vertical and horizontal error is presented in a previous work: when the error is accepted as random the PDEM may evaluate the vertical error, - without systematic error as it happens using the vertical distance method- and also may evaluate the horizontal one (horizontal isotropic error) under certain irregular terrain conditions, without using benchmarks. In the case of the DEM obtained by IFSAR techniques, the error in the vertical axis is correlated with the error in the range-axis. A rotation has to be done to find not correlated directions. The contribution of this paper is to assess the PDEM effectiveness to estimate the error in the three not correlated directions: the beam axis, the azimuth axis and the axis normal to the previous two (y’; the rotated range axis). Simulations are presented in detail, starting from a real reference DEM, with 100 000 points. The results confirm that the PDEM error estimation is good in the beam and in the y’ directions, and the more uneven the terrain, the better the estimate of the azimuth axis error.