Compact 3D Representation using Octrees and Affine Transformations

by Youyou Wang

Introduction

    In this research we developed a new and compact 3D representation for non-rigid objects using the motion vectors between two consecutive frames. Our method relies on an Octree to recursively partition the object into smaller parts. Each part is then assigned a small number of motion parameters that can accurately represent that portion of the object. The partitioning continues as long as the respective motion parameters are insufficiently accurate to describe the object. Unlike other Octree-based methods, our method employs an affine transformation for the motion vectors, and consequently, greatly reducing the storage. Finally, an adaptive thresholding, a singular value decomposition for dealing with singularities, and a quantization and arithmetic coding further enhance our proposed method by increasing the compression while maintaining very good signal-noise ratio. Compared to other methods that use tri-linear interpolation, Principle Component Analysis (PCA), or non-rigid partitioning (e.g. FAMC) our algorithm combines the best attributes in most of them. For example, it can be carried out on a frame-to-frame basis, rather than over long sequences, but it is also much easier to compute. In fact, we demonstrate a computation complexity of (n2) for our method, while some of these methods can reach complexities of O(n3) and worse. Finally, as the result section demonstrates, the proposed improvements do not sacrifice performance since our method has a better or at least very similar performance in terms of compression ratio and PSNR.

Octree structure after partitioning based on motion analysis.

    Results

Comparison between our proposed method and ZhangOwen's and AmjStarb's algorithms

Comparison between the FAMC+DCT [MamZahPre08] and our proposed method

    References

1. Y. Wang, and G. N. DeSouza, "A Compact Representation for 3D Animation using Otrees and Affine Transformations", International Journal of Digital Multimedia Broadcasting on Advances in 3DTV: Theory and Practice, Vol. 2010, Article ID 924091, pp. 11, 2010.

2. Wang, Y. and DeSouza, G. N., "A New 3D Representation and Compression Algorithm for Non-Rigid Moving Objects using Affine-Octree", in Proceedings of the 2009 IEEE International Conference on Systems, Man, and Cybernetics (SMC), pp. 3848-3853, Oct/2009.