AUTOMATIC INTEGRATION OF FOLIAGE INTO 3D CITY MODELS - Real-Time Tree Extraction and Rendering Based on Seasonal Large Scale Aerial Pictures Topics: Image-Based Rendering; Modeling of Natural Scenes and Phenomena; Real-Time Graphics; Real-Time Rendering In Proceedings of the Second International Conference on Computer Graphics Theory and Applications - Volume 2: GRAPP, 299-304, 2007 , Barcelona, Spain