Development of Algorithms for the Exploitation of ERS-ENVISAT data by using the Stable Points Network technique.

During the last ten years a vast amount of ERS-1 and ERS-2 data - offering for a wide range of interferometric applications - was acquired by the SAR sensors of the two satellites. In 2002, the more advanced satellite ENVISAT was launched.

The SAR instrument on board of ENVISAT (ASAR) has the potential to continue the success of the remote sensing mission of the ERS satellites and preserve or even increase the value of the archived ERS data.

The EEE-SPN project financed by ESA (Contract N°16702/02/I-LG) has the aim to develop the algorithms needed for the joint exploitation of ERS and ENVISAT SAR images using the Stable Points Network technique.

Objectives

The objectives of the ALTAMIRA INFORMATION led project are two-fold:

•	to demonstrate the implementation of stable points network interferometry with ENVISAT at the same quality than with ERS: continuity of phase measurements
•	to demonstrate the possibility of using ERS and ENVISAT SAR images together for the stable points network technique: feasibility of cross-interferometry

Phases of the project

The project was organized into several tasks with the following specific details:

Theoretical aspects

Given the technological evolutions that occurred between ERS and ENVISAT the following theoretical questions had to be answered:

•	implementation of stable points network interferometry for ENVISAT in the same way as it is done with ERS
•	usage of ERS and ENVISAT SAR images together
•	investigation of the advantages of the advanced acquisition modes offered by ENVISAT

Algorithms development

•	development of algorithms needed for the implementation of the Stable Points Network Technique
•	development of a browser allowing to quickly select images suited for the implementation of the technique in order to offer an easier access

Validation

Thorough validation of the technique on several test sites providing for:

•	various application domains (urban subsidence, mining subsidence) and different technical interests (SPN technique demonstration but also cross interferometry, MERIS exploitation, corner reflectors experimentation).
•	APS approximation obtained from MERIS data will be used for validation of the APS retrieved by the SPN prototype