This paper describes the real-time mapping displacement of buildings onto the polygon model of base terrain of geo-spatial information. The buildings are represented as height maps, leading to low memory requirements and not involving changes of the original geometry (i.e., no vertices are created or displaced). The displacement of buildings is mapped toward the protruding direction. The base of texture which represents the ground in topography is correctly mapped onto base polygon without any distortion. This approach can exhibit the correct occlusions between buildings and ground due to parallax and correct self-occlusion.