A method of defining deviations from a desired position of pixel sites in an image recording matrix by defining the 3-D data of a planar or slightly curved surface. To the extent necessary the results are smoothed, and the measuring points, utilizing the 3-D data, are projected back the sensors of the image recording matrix for determining the difference between the two points projected onto the sensors and associated with a 3-D measuring point. After selectively shifting the surface relative to the 3-D measuring system, prior method steps are repeated until the desired accuracy in the definition of the deviation has been has been attained.