Extraction des cretes de pression sur images radarsat en mode fin

摘要

First-year ice pressure ridges are regions with brighter return than the background. However, in most cases, only a few ridges are contrasted enough to allow their extraction. We present data recorded during the spring melt. With the increase of the water content in snow, SAR energy is mainly diffused and reflected at the snow-air interface masking everything but ice blocks emerging from the snow cover. On the other hand, the development of a wet film on ice blocks increases their return and therefore the resolution of pressure ridges. As melt goes on, a larger proportion of ridges coming out of the snow, we obtain an image on which the ridge-plate contrast allows the extraction of most of the ridge network. We show, in addition, that ridges are not only characterized by bright linear structures. Bright structures are paralleled by a band which return is lower than the background This explains why, standard beam images which integrate those two structures in single pixels, don't give good results.