In recent year, much progress has been made in outdoor 3D mapping. However, 3D mapping in real time is still a daunting challenge in urban environment. This paper addresses the problem of 3D mapping from 3D laser scans in urban environments in real time. To do this, we proposed geometric featured voxel which can efficiently represent 3D urban structure without loss of geometric properties. For evaluation of the proposed voxel, we use Oakland dataset.