Design of a color coded target for vision measurements

As a category of special control points which can be automatically identified, artificial coded targets have been widely developed in the field of computer vision, photogrammetry, augmented reality, etc. In this study, a novel color coded target is designed for vision measurements. A reference position is defined to avoid the repeated coding as well as simplify the coding structure, and a pair of concentric circles is utilized for the precise location of the target. An edge-based identification and location algorithm is proposed for the designed coded target. In this algorithm, a coarse-fine strategy is employed to improve the efficiency and various judgments are made to ensure the correctness of the identification. No human involvement is required except for the adjustment of thresholds in the beginning, which is conducive to the automation of measurement. The algorithm shows high accuracy and robustness in experiments. (C) 2014 Elsevier GmbH. All rights reserved.