Study on Sub-pixel Location of Ci rcle Target Based on Unmixing the Mixed Pixels

The location of circle target in the image is very important to digital photogrammetry.Sub-pixel edge positions of the target are got by sub-pixel location in mixed pixels of the target edge.Then,the center position of the circle target are calculated by the least squares elliptical fitting.Three experiments prove that the precision of this location method is higher than the precision of traditional method that elliptical fitting with pixel edge.