| 摘要 |
A method of estimating the position of the field of view of an imaging device, such as a camera, relative to a board involves designating markings on the board as references and detecting the shift in these reference markings within the field of view of the camera compared to a known position therein. The reference markings are selected such that detection thereof involves analysis of only a subset of the image produced by the imaging device. The selection of a group of one or more markings to serve as a reference involves determination of the image region (error window) in which the reference marking(s) may appear, given the maximal positional error of the imaging device. It is also checked (step T4) that the entire error window will be within the useable field of view of the imaging device and that, within the error window, no other group of markings will appear that could be confused with the selected group of markings (step T5). Detection of the reference group of markings involves generation of an image profile along a line crossing the center of the error window and finding the best match between the markings along this profile and the markings in the reference group.
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