Automatic Interior Orientation of Aerial Photographs with Model-free Condition

This paper proposes an approach of automatically calculating the center location of fiducial marks up to sub-pixel accuracy with model-free condition. The conceptual model, composed of two assumptions, about general geometric property of fiducial area and fiducial mark is established. The proposed approach is primarily based on the strategy of calculating the center of symmetry and is composed of three steps of processing: (a) determining horizontal center of fiducial area, (b) locating center of a fiducial mark, and, (c) finally calculating the exact center up to sub-pixel accuracy. Evaluation with respect to RMK style marks and RC style ones shows that the proposed approach can be evaluated as robust one. However there are several images which can't be analyzed by the proposed approach.