Geographic Data Base Enriching from ERS SAR Scenes: Examples in French Guiana

Geographic information system accessibility and popularity play an important role in spatial and temporal analysis of anthropic and natural activities. Optical images are not efficient for geographic data base on the French Guiana because of its characteristics (cloud cover, dense forest cover). A series of applications have been integrated in a G.I.S. on French Guiana. SAR ERS data are used as cartographic resource when available ones are obsolete, as environmental data source, and also to enrich and bring up to date available vector layers (by classification process or photo-interpretation). We have a global ERS SAR PRI cover of the territory at our disposal and multi-temporal sequences on the coastal plain. Because of the effect of speckle, isolated scenes are, in general cases, only useful for small scale map (about 1 : 200 000). But this scale is not proportional with available vector layers. SAR sequences are filtered with a multi temporal filter so as to increase the image quality by reducing the variance of the speckle. The average scenes are used for applications that require larger scale map (1 : 50 000). The capacity of ERS SAR sensor to enrich geographic data bases is valorized by some application examples : developments, health (malaria zones), natural cover and deforestation , coastal cartography.