Constrained finite element method self-calibration

Polynomial correction models have become standard tools in analytical photogrammetry for attenuating image distortions. An alternative model stems from the fact that the displacement of a point in the image plane is projectively equivalent to a proportional change in focal length. By dividing the image plane into smaller entities, distortions can be modeled by piecewise focal length variation using the finite element method of self-calibration.

This thesis presents an investigation into a modified finite element approach to camera calibration. Comparisons are made with results from an accepted polynomial model. The effects of increasing the number of finite elements are examined for three different CCD camera and lens combinations. The application of continuity constraints between element shape functions is also analysed. The evaluation criteria include the degree of compensation for distortions, object space precision and accuracy and parameter correlation.