In order to be able to compare an interferometrically derived DEM with a reference model, such a reference model needs to be accessable. This can be a problem in remote areas where no additional information is available. The use of a reference model for a comparison is done assuming that this model is reliable and without any distortions. From the statistical point of view, a reference DEM with an accuary, which is one order better than the InSAR DEM, is required. The result of the comparison of the DEMs gives a quantitative measure how well the two elevation models fit together.
Any systematic errors remain undetected.
To overcome these problems, we estimate the quality of an InSAR DEM using an error propagation model based on an empirical approach. The theoretical background and the implementation of this error propagation model is described in the following chapters. The error propagation model is implemented in an empirical way because this needs only a limited knowledge about the software used for the processing. The values of all input parameters as well as their accuracies are needed in the model. A list of all output parameters is also required.