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Posable human hand modeling from One-shot range scans

We aim to build a posable 3D human hand model. It is desirable that the hand model is realistic and individualized for some applications. Although it is effective to perform 3D shape measurement of an actual human hand, it is not easy to measure the 3D shape of hands, which are small and have complex shapes.

A method of modeling a human hand on only measurement is proposed that acquired 3D shapes of not only the surface but the bones as its structure by using MRI, which needs long time for measurement. Another method uses a template model which has prior knowledge of a human hand shape and structure. The method requires few seconds for measurement to acquire a hand model, but the model was not necessarily the same as the measured hand. Therefore, we aim to reconstruct a hand model by measuring it in many poses by one-shot range scanning, which can acquire shapes for a moment, and using less prior knowledge that hands are composed of some rigid parts which approximate each finger segment.

One-shot range scans include partial shapes of several finger segments. For building a whole shape for each segment, we segment the scans by using spaces where objects don't exist in time of one-shot range scanning. First, we measure the rigid motion of each segment during the scanning. Second, we transform the scans and the spaces into the same coordinates based on the motion of certain part. The shapes not belonging to the part can be transformed inside of the spaces although the ones belonging to it always stay outside of the spaces. Based on this principle, we remove the shapes by using these spaces and acquire the shape of each segment. Then a hand model in various poses can be formed by aligning them adequately.

We validated necessary poses and the observation directions for our method, by using a wooden hand composed of 4 parts. In addition, we modeled an actual human hand by assuming that it is composed of 18 parts.