In this talk, we present a new geometry reconstruction algorithm from a sequence of images of a rigid object. The main idea of the algorithm is the following. For a moving object in a constantly illuminated environment, the relative motion between the object and the illumination source will produce a variation in intensity values, and this provides an important cue for solving the reconstruction problem. In particular, it allows us to compute the normal vector field of the object's surface, and hence, the depth (3D structure) relative to the camera can be recovered by integrating the normal vectors. The iterative algorithm we proposed is quite simple and yet effective. Using some differential geometry, we will discuss the algorithm's convergence in the second part of this talk.