The suitability of multifrequency, multipolarimetric and multitemporal radar data for forest monitoring

From the two SIR-C/X-SAR Missions in April and October 1991 for the Oberpfaffenhofen supersite southwest of Munich/Germany numerous data sets with different acquisition modes are at disposal. All used datasets were calibrated, so that the backscatter coefficient in dB (decibel)-values can be compared directly. The SIR-C data were geometrically adapted to the geocoded X-SAR data via image to image registration. Field observations and aerial photographs have been made for ground truth data. The analytical evaluation of the aerial photographs has been a very important step during the investigation of the information content. Results from visual comparisons and signature analysis have shown, that neither tree species nor stand composition influence radar signals markedly, but structural characters like altitude differences of trees and shrubs as well as vegetation density or gaps do. The authors conclude that in their case the highest spatial resolution is more important than the full polarimetric resolution