Figure 1: Reconstruction of a space-time surface. Left: A sequence of point clouds of a running man containing holes due to self occlusions. Middle: Renderings of two iterations of our flow solver. Cells confidently identified as being inside the surface are colored dark blue. As the solver progresses, mass accumulates inside the surface. Right: The result of an implicit function reconstruction from the flow solution. Abstract We introduce a volumetric space-time technique for the

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... of moving and deforming objects from point data. The output of our method is a four-dimensional space-time solid, made up of spatial slices, each of which is a three-dimensional solid bounded by a watertight manifold. The motion of the object is described as an incompressible flow of material through time. We optimize the flow so that the distance material moves from one time frame to the next is bounded, the density of material remains constant, and the object remains compact. This formulation overcomes deficiencies in the acquired data, such as persistent occlusions, errors, and missing frames. We demonstrate the performance of our flowbased technique by reconstructing coherent sequences of watertight models from incomplete scanner data.