Restitution of Information under Shadow in Remote Sensing High Space Resolution Images: Application to Ikonos Data of Sherbrooke City

Shadow regions are very present in the high spatial resolution images, particularly in urban environment. Shades have negative effects. They strongly disturb the classical techniques of image analysis by modifying surface appearance and sometimes involve loss of information under the surface they covered. In this study, we try to restore the information masked under the shadow by finding the types of surface covered by the shade. This search is based on the analysis of contextual, spectral and textural information from the shadow and its vicinity.This restitution supposes that shades are well identified, which was the aim of our former work. It takes into account the space configuration of the vicinity between the objects located sun side and surfaces in shade side which are supposed to receive the shadow. The application on an IKONOS image of Sherbrooke show that it is indeed possible to restore the information laying under the shadow and even discriminate several types of surface under the same shade, such as shades of buildings which are projected at the same time on grass, a portion of parking or on another building. The method also makes it possible to correct the shadow effects on the images.