A practical target recognition system for close range photogrammetry

This paper presents details of a coded target system that employs polar coordinate transformation and segment matching to automatically recognise and identify targets in digital images. The code system is based on a square surrounding the central circular target and is described at a level of detail that would allow the system to be readily duplicated. Pre-detection processes, developed to improve the success rate under unfavourable conditions, and the tests conducted to validate a correct target match, are described. Finally, the paper includes some examples of the use of the coded targets, drawn from a variety of calibration and measurement applications.