The University of North Carolina at Chapel Hill Department of Computer Science FALL 1994 COURSE ANNOUNCEMENT COMP 290-066: Theory and Implementation of Ridges Instructor: Dr. David Eberly Times: 11:00-12:15 T Th SN 325 (115 available as needed) Credits: 2 or 3 (it's scheduled to permit 3, but actual credit may be negotiated with instructor) Call number: 10043 Prerequisites: Background in Calculus and Linear Algebra. Numerical Analysis (COMP 151) will be helpful, but not essential. Description: The definition of "ridges" for a real-valued function of N independent variables is an extension of the definition for strict local maxima. Intuitively, a strict local maximum is a point for which the function has a local maximum in N linearly independent directions. These points are isolated and can be thought of as 0-dimensional sets. A D-dimensional ridge point is a point for which the function has a local maximum in N-D linearly independent directions. The choices of ridge dimension and the directions are typically made based on the geometric nature of the application. The selection of the word "ridge" is motivated by the case N=2 and D=1. If you consider the graph of the function as mountainous terrain, the strict local maxima correspond to mountain peaks. The 1-dimensional sets obtained by finding local maxima in special directions resemble the ridges of the terrain. The concept of ridges appears to be useful in many applications. In particular, the Medical Image Display Research Group at UNC uses ridges for determining medial and boundary representations for objects in medical images. Other applications which use ridge theory include building representations of arterial structures from angiograms, determining molecular structure from potential energy data, and finding locations of high pressure in air flow over wings. Outline: (1) Present the basic theory of ridges (as a continuous model). (2) Discuss how to formulate the definitions in a way that allow computation of ridges from discrete data. (3) Numerical implementation of ridge construction. Topics which will be covered in detail are: (a) B-spline interpolation (continuous representation of discrete data) (b) Householder method for solving eigensystems (c) Gradient descent algorithms (d) Methods for solving systems of ordinary differential equations (4) Application to medical image analysis (5) Application to molecular modeling (6) Application to fluid dynamics (if time permits)