When monitoring urban areas from space, change detection based on satellite images is one of the most heavily investigated topics. In the case of monitoring change in 2D, one major shortcoming consists in the lack of height change detection. Thereby only changes related to reflectance values or local textures changes can be detected. However, changes in the vertical direction are completely ignored. In this paper we present a new 3D change detection approach. We focus our work on the detection of changes using Digital Surface Models (DSMs) which are generated from stereo imagery acquired at two different epochs. The so called "difference image" method is adopted in this framework where the final DSM is subtracted from the initial one to get the height difference. Our approach is a two-step approach. While in the first step, reduction of the noise effects (coming from registration noise, matching artifacts caused by the DEM generation procedures, etc), the second one exploits the rectangular property of the building shape in order to provide an accurate urban area monitoring change map. The method is tested, evaluated and compared with manually extraction results over the city centre of Munich in Germany
