Shape Modeling and Alignment:
                   Applications to Biomedical Informatics

                                 Heng Huang
                         Computer Science Department
                              Dartmouth College

                                  ABSTRACT

Shape modeling and surface representation combine  physical  measurement  of
objects with mathematical models and are important  in  a  large  number  of
scientific and engineering areas. Biomedical informatics is one of the  most
important applications. In this talk, I will present two recent  results  on
shape modeling and registration  with  several  applications  in  biomedical
informatics.

In the first work,  I  show  a  novel  surface  registration  algorithm  for
arbitrarily shaped but  simply  connected  (i.e.,  contiguous)  3D  objects.
Based  on  the  rotational  properties   of   harmonic   analysis,   a   new
Parameterization Rotation Theorem  is  introduced  and  proved  and  a  fast
surface alignment algorithm is developed. This algorithm can accurately  and
efficiently generate  surface  correspondences  between  objects  for  which
spherical  harmonics  (SPHARM)  was   used   for   surface   modeling.   Its
computational complexity is improved from the O(n3) of previous  methods  to
O(n2). These techniques have been applied in many  biomedical  applications,
including improving  morphological  understanding  of  anatomic  structures,
dynamic analysis (e.g. of beating hearts), and assisting  in  medical  tasks
like pacemaker placement.

In the second work,  I  present  a  new  hemisphere-based  harmonic  surface
model. We define a set of complete hemispherical  harmonic  basis  functions
on a hemisphere domain and use these to support  a  novel  parametric  shape
description method. This method is very useful in efficiently  and  flexibly
representing the surfaces of certain anatomical structures (like  the  heart
ventricles) in biomedical applications.


Brief Bio: Heng Huang received a BS (1997) and MS  (2001)  from  Electronics
and Information School at Shanghai Jiao Tong University. He is  currently  a
Ph.D. candidate in the Department of Computer Science at Dartmouth  College,
where he works in medical informatics and bioinformatics.