Automatic 3D building modeling in dense urban areas is challenging because, especially in Japan, houses that have slant roofs are located close to each other, and their heights are similar. For this case, difficulty in separating point clouds into individual buildings is an obstacle to modeling. I have developed an algorithm that automatically generates 3D building models even in dense urban areas. The proposed algorithm uses the results of building segmentation from aerial photographs. Segmentation of buildings in urban areas, especially dense urban areas, by using remotely sensed images is also challenging because of unclear boundaries between buildings and shadows cast by neighboring buildings. I have developed another algorithm that segments buildings, including shadowed buildings, in dense urban areas from an aerial photograph. By considering the segmented regions and airborne light detection and ranging (LiDAR) data, models of actual building types-gable-roof, hip-roof, flat-roof and slant-roof buildings-are generated.