Geometric Image Measurement Errors of Circular Object Targets

The use of ciruclar object targets is very common for a spatial photogrammetric object reconstruction. An object circle is projected on the image plane as an ellipse, if the object plane and the image plane are not parallel. The image coordinates of the center of the ellipse and the true coordinates of the projected center of the circular target are not identical (eccentricity) resulting in systematic geometric image measurement errors. Possibilities for a correction of this systematic eccentricity error are proposed.