# An Efficient and Robust Ellipse Detection Method for Spacecraft Docking Rings in Complex Scenes

## TL;DR

This paper introduces a new method for detecting ellipses in spacecraft docking rings, even when parts of the rings are hidden.

## Contribution

A novel ellipse detection method using arc-support line segments and hierarchical quadrant division for robust spacecraft docking ring detection.

## Key findings

- The method uses arc-support line segments and quadrant division to detect ellipses efficiently.
- A comprehensive scoring system selects optimal ellipses based on edge density and continuity.
- Dynamic arc pruning improves detection quality by removing redundant arcs.

## Abstract

The key components of spacecraft are typically present as circular or near-circular structures, and their precise and rapid extraction is essential for spacecraft attitude estimation. In response to the high precision and robust detection of ellipse components on space non-cooperative targets such as spacecraft docking rings, this paper proposes an efficient and robust ellipse detection method. This method first uses the arc-support line segment method to extract ellipse arc segments and then employs a hierarchical quadrant division strategy with a “coarse-to-fine” approach, integrating multiple constraints such as angle, quadrant, and relative position to combine arc segments and generate ellipse candidates. It uses a comprehensive score based on edge density, global coverage and local continuity to select the optimal ellipse from among the valid ellipses. Finally, a dynamic arc segment pruning method is introduced to dynamically remove relevant arcs from optimal ellipses, obtaining high-quality and non-redundant detection results. This method can achieve robust ellipse detection even when docking ring contours are partially obscured by shadows from robotic arms or nozzles.