Persistent scatterer processing validation in the course of the Terrafirma project

Terrafirma is an ESA project and a services element in the framework of the Global Monitoring for Environment and Security (GMES) service element programme. Based on the Persistent Scatterer Interferometry (PSI), the project provides a Pan European ground motion hazard information service. The motion monitoring is supplied by commercial companies which act as Operational Service Providers (OSPs). A Product Validation Workgroup (PVW) has been formed for the validation and certification of the various motion data products which can provide different levels of value adding. Four OSPs operate processing chains for the generation of the basic level 1 product. These take part in a validation project which intends to demonstrate reliability and accuracy of the PSI motion monitoring. Amsterdam and Alkmaar in the Netherlands are the two test sites which are chosen for the comparison. Three data stacks - two from Envisat and one from ERS are processed independently by the OSPs in the course of the validation. Two strategies for the validation are foreseen in the validation project: on the one hand the Product Validation and on the other the Process Validation. Both are independent and complementary to each other. The Product Validation utilizes available ground truth information for the validation and assesses the final geocoded motion data. The Process Validation is a new type of PSI validation and compares the intermediate data in slant range only and consequently avoids problems of geocoding, misregistration and interpolation. This comparison is made by the German Aerospace Center (DLR) with assistance of the Institute of Geomatics (IG) which leads the overall validation project. The new validation approach and the intermediate validation results are reported.