PERCEPTION OF A GEOLOGICAL BODY USING MULTIPLE SOURCE REMOTELY-SENSEDDATA - RELATIVE INFLUENCE OF THE SPECTRAL CONTENT AND THE SPATIAL-RESOLUTION

Fracturing maps over a granitic dome (Scaer granite, Brittany, France) have been extracted from the most widely available remotely-sensed da ta and from aerial photographs. Comparison of the different maps obtai ned allowed the classification of the mapping potential of the differe nt raw and merged images as well as ranking their ability to point out geological features at different scales. Three different types of geo logical features were pinpointed: a coarse regional fracturing, kilome tric plutonic domes and finer geological structures such as circular f eatures within the granitic dome. The best means of revealing each of these three types of geological features, proved to be radar images, m ulti-spectral data and aerial photographs, respectively. The data prov iding the largest range of scales of observation and the greatest amou nt of information on geological structures and soil types were the mer ged Landsat-TM and SPOT panchromatic images.