A system for efficient 3D printed stopmotion face animation. Computer animation in conjunction with 3D printing has the potential to positively impact traditional stopmotion animation. As 3D printing every frame of a computer animation is prohibitively slow and expensive, 3D printed stopmotion can only be viable if animations can be faithfully reproduced using a compact library of 3D printed and efficiently assemblable parts. We thus present the first system for processing computer animation sequences (typically faces) to produce an optimal set of replacement parts for use in 3D printed stopmotion animation. Given an input animation sequence of topology invariant deforming meshes, our problem is to output a library of replacement parts and peranimationframe assignment of the parts, such that we maximally approximate the input animation, while minimizing the amount of 3D printing and assembly. Inspired by current stopmotion workflows, a user manually indicates which parts of the model are preferred for segmentation; then, we find curves with minimal deformation along which to segment the mesh. We then present a novel algorithm to zero out deformations along the segment boundaries, so that replacement sets for each part can be interchangeably and seamlessly assembled together. The part boundaries are designed to ease 3D printing and instrumentation for assembly. Each part is then independently optimized using a graphcut technique to find a set of replacements, whose size can be user defined, or automatically computed to adhere to a printing budget or allowed deviation from the original animation. Our evaluation is threefold: we show results on a variety of facial animations, both digital and 3D printed, critiqued by a professional animator; we show the impact of various algorithmic parameters; and compare our results to naive solutions. Our approach can reduce the printing time and cost significantly for stopmotion animated films.

Segmentation and compression techniques for 3D animation models based on motion trajectory in the spherical coordinate system In recent days, applications using 3D animation models are increasing. Since the 3D animation model contains a huge amount of information, data compression is needed for efficient storage or transmission. Although there have been various proposals for 3D model coding, most works have considered only static connectivity and geometry information. Only a few studies have been presented for 3D animation models. This paper presents a coding scheme for 3D animation models using a new 3D segmentation algorithm. For an accurate segmentation, we take advantage of temporal coherence in the generic animated 3D model. After the motion vector of each vertex is mapped onto the surface of the unit sphere in the spherical coordinate system, we partition the surface of the sphere equally to have the same area. We then reconstruct inbetween 3D models using the reconstructed key frame and an affine motion model for each segmented unit.