Closed Boundary Offset From the Medial Axis

Abstract

Closed boundary orthogonal offset has been a default function in many CAD systems and has applications in manufacturing engineering such as toolpath generation and computer science fields such as image processing. Most current solutions to this function are limited to the single boundary inputs composed of linear segments and circular arcs. This paper describes a novel method to generate the approximate offsets of closed boundaries directly from the associated medial axis. The method accepts both single boundaries and multi-connected boundaries as input. The local and global intersection problems are entirely avoided. An extended discrete medial axis transform construction algorithm for multi-connected boundaries is introduced. The associated tree structure storing the medial axis data is generated along with the medial axis. The discrete characteristic of the medial axis construction method also gives the offset method the advantageous potential to handle B-spline inputs.