Automatic Measurement of Circular Artificial Targets in Digital Image

Image coordinates measurement is one of key links in close-range photogrammetry, such as in camera calibration in control fields or in a surveying procedure of artificial targets pasted on surface of lacking texture object. An automatic measurement algorithm about image coordinates of circular artificial targets is researched in this paper. An automatic measurement strategy of artificial targets is put forward, and the main content includes rough positioning of targets in image by direct linear transformation, adaptive image window determination according to the actual size of artificial target and window movement to measure image coordinates of target. Experiments prove that the method is able to complete the automatic measurement of image coordinates of artificial targets with high efficiency.