Surface Construction and Comparison using Manifolds

Washington University, Saint Louis MO

Investigators

Abstract

This research focuses on the comparison of surfaces which are similar, but not identical. For example, almost all leg bones are similar in shape (a cylinder with knobs on the ends) but may differ greatly in length, diameter, size and shape of the knobs, etc. The goal of this research is to provide robust methods for comparing, categorizing, and analyzing surfaces of this type. Researchers in the bio-medical, physical anthropology, and forensics fields, to name a few, currently rely on human experts to perform these measurements. The types of measurements they can make are also limited to simple ones, such as length and circumference. These measurements are used to answer questions such as: What race/sex is this bone from? How tall was the person? Is the surface is abnormal? Was there an injury at some time? Why does the joint not function normally? Analytical measurements will not only remove the (sometimes subjective) human component, but will also broaden the scope of surface comparison beyond simple length measurements. The first part of this research is a constructive approach for creating manifolds of arbitrary topology. These manifolds provide a natural mechanism for analyzing specific subsets of the surface via the creation of local maps that cover any desired portion of the surface. Manifolds also provide a parameterization mechanism for identifying corresponding points on surfaces. The research addresses theoretical issues related to manifolds such as improved local map placement, more controllable blend strategies, manifolds with boundary, and using manifolds to parameterize existing meshes or point clouds. The second part of his research, detailed surface comparison, is a relatively novel task, and includes a well-posed statement of the problem in addition to the development of algorithmic solutions. For example: What is a feature? How do we quantitatively measure feature differences in a meaningful way? How do we measure the quality of the correspondence between two surfaces?