Objectives The circular coded marker is widely used in close-range photogrammetry, and has excellent characteristics that are independent of translation, rotation, and scaling. The robust recognition and decoding of the circular coded markers are of great significance to the subsequent 3D reconstruction.
Methods Aiming at the identification of coded marks in complex environments such as cluttered backgrounds and uneven lighting, a two-step contour screening strategy is proposed. First, coarse screening is performed based on the contour length and roundness, and then fine screening is performed based on statistical analysis on gray-scale distribution.
Results The experimental results show that when the shooting angle is less than 75° and the size of the code point is greater than 30 pixels, the proposed method can guarantee high accuracy in recognition and decoding. In a complex environment , the recognition accuracy and decoding accuracy are 99.53% and 100%, respectively, and the false recognition rate is 0%.
Conclusions The proposed method can effectively reduce the false recognition rate and have a good recognition effect in a complex environment.
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