Method of calibration of imaging devices

Abstract

A method of calibrating a linear pushbroom imaging device used in non-destructive testing of a part manufactured according to a CAD model involves identifying the location of fixed reference points, such as tooling balls in the CAD model. Positioning the part on a fixture having tooling balls fixed relative to each other in the same manner as those in the CAD model. Adjusting the part on the fixture such that points on the surface of the part known to be accurate have the same locations relative to the tooling bails as the CAD part is to the CAD tooling balls. Obtaining several projection images of the part and tooling balls at different angles about an axis of rotation passing through the part. Using the known 3D locations of the center of the CAD tooling balls and the corresponding measured screen locations of the is actual tooling balls, transformation matrices, G, M.sub.j may iteratively be determined which map points on the 3D CAD model to 3D points of the part and then map the 3D points of the part to the 2D screen coordinates of each projection image, respectively. This provides a method of determining theoretical correct point locations in a coordinate system fixed with respect to the part, and theoretically correct screen coordinates in a reference frame fixed with respect to the imaging device.