Model and context‐driven building extraction in dense urban aerial images

This paper presents a method to extract buildings in monocular urban aerial images without prior knowledge of illumination. With a building concept model to interpret buildings at different levels and scales, building extraction is carried out in two stages: sunshine parts extraction and self‐shadow parts extraction. Based on region‐oriented radiometric features, images are first simplified and segmented into three parts: sunshine parts of high objects, shadow regions and sunshine ground. To verify initial segmentations, a method of estimating the direction of shadow cast was proposed by a shadow context model. Building extractions were then refined by context and a modified partial snake model with the aid of the shadow cast direction, thus sharply reducing the iteration complexity and the influence of illumination. An innovative method for extracting self‐shadows on gable roofs is also discussed.