---
title: "A Hierarchy of Boundary-based Shape Descriptors"
authors:
  - "Richard C. Meathrel"
  - "Antony Galton"
doi: ""
url: "https://ijcai.org/proceedings/2001/179"
pdf: "https://ijcai.org/proceedings/2001/0179.pdf"
venue: "Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence"
year: 2001
pages: "1359-1363"
track: ""
keywords:
---

# A Hierarchy of Boundary-based Shape Descriptors

Richard C. Meathrel, Antony Galton

*Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence*, pages 1359-1363.

## Abstract

In this paper we extend previous work on the boundary-based approach to describing shape, by deriving an unbounded hierarchy of “atomic” shape descriptors (called tokens) based on tangent bearing and its successive derivatives, and incorporating angle and cusp curve features. Both open and closed curves have token-string descriptions at all levels in the hierarchy. We provide a pair of compatibility matrices for generating transition tables for any level, from which level-specific token ordering graphs that encode basic string syntax can be systematically constructed.