A Fast Ellipse Detector Using Projective Invariant Pruning

TL;DR

This paper introduces a rapid ellipse detection algorithm that uses a projective invariant to efficiently prune non-elliptical candidates, significantly improving speed while maintaining high accuracy for real-time applications.

Contribution

The novel use of a projective invariant based on simple determinant calculations to prune and identify elliptical curves in images is the key innovation of this work.

Findings

Runs 20%-50% faster than existing methods

Achieves comparable or higher detection precision

Effective on challenging datasets with 650 images

Abstract

Detecting elliptical objects from an image is a central task in robot navigation and industrial diagnosis where the detection time is always a critical issue. Existing methods are hardly applicable to these real-time scenarios of limited hardware resource due to the huge number of fragment candidates (edges or arcs) for fitting ellipse equations. In this paper, we present a fast algorithm detecting ellipses with high accuracy. The algorithm leverage a newly developed projective invariant to significantly prune the undesired candidates and to pick out elliptical ones. The invariant is able to reflect the intrinsic geometry of a planar curve, giving the value of -1 on any three collinear points and +1 for any six points on an ellipse. Thus, we apply the pruning and picking by simply comparing these binary values. Moreover, the calculation of the invariant only involves the determinant of a 3*3 matrix. Extensive experiments on three challenging data sets with 650 images demonstrate that our detector runs 20%-50% faster than the state-of-the-art algorithms with the comparable or higher precision.