An efficient 3D object management and interactive walkthrough for the 3D facility management system

An efficient 3D facility management system is developed based on the spatial data structure(MD-tree). In the system, 3D objects in a city are semi-automatically generated from 2D-maps by using appropriate rules. The entire 3D space is sliced into multiple layers depending on the height. The objects that belong to each layer are managed by corresponding 2D MD-tree. Potentially visible objects are obtained efficiently by the data management method based on the multiple MD-trees. The objects close to the viewpoint are searched in the MD-tree that corresponds to the lower layer. Far objects are, on the other hand, searched in the higher layer. The search operation is performed very rapidly by MD-tree. Furthermore, the rendering complexity of each object is adaptively controlled with respect to the the distance from the viewpoint so that the scene complexity is kept bounded. With these techniques, desirable frame update rates for the interactive walkthrough (around 10 frames/sec by SGI CRIMSON/Reality Engine) is realized