The influence of target distance to lens distortion variation

Using wide angle lenses images usually suffer from lens distortion. This distortion must be corrected if the images are used for measurements, e.g. for the solution of photogrammetric tasks. If the distance between the lens and the measuring object is short, the distance dependence of lens distortion must be considered, too. This fact is often neglected in recent work. However, disregarding the distance dependence of lens distortion leads to considerable measuring errors in optical measuring systems. The amount of the distortion may change in a range of a few centimetres distance variation up to a scaling factor of 1.6. In this paper two new models describing distance dependent lens distortion are introduced. The first is based on a 3D matrix of distortion vector representatives. The main task of the connection of several 2D distortion matrices to a common 3D model is the normalized connection of the separately produced 2D distortion matrices. The second one is realized by a functional description of the lens distortion depending on three parameters in the image space. Actually occurring distance depending lens distortion of different camera systems is shown and several application results illustrate the potentialities of the new correction procedure.