6. Conclusion
We proposed a novel descriptor called PTI. By encoding the thickness information of input 3D models, the PTI is not only invariant to the basic geometric transformation, such as translation, rotation, and scaling, but also insensitive to quasiisometric deformations, e.g., human body poses. Benefitting from partial volumetric information, the PTI is robust to small geometric noise added to the vertices of 3D models. To apply the PTI to 3D model classification, we combined the PTI with KSRC and presented a new 3D model classification algorithm. Extensive experimental results demonstrate the high accuracy, robustness, and effectiveness of our algorithm. However, we found that the MDS technique generally introduces shape distortion especially at extremity points although it basically eliminates pose differences. We will study if it is possible to obtain a better MDS method without shape distortion.