  Fisheye cameras prove a convenient means in surveillance and automotive
applications as they provide a very wide field of view for capturing their
surroundings. Contrary to typical rectilinear imagery, however, fisheye video
sequences follow a different mapping from the world coordinates to the image
plane which is not considered in standard video processing techniques. In this
paper, we present a motion estimation method for real-world fisheye videos by
combining perspective projection with knowledge about the underlying fisheye
projection. The latter is obtained by camera calibration since actual lenses
rarely follow exact models. Furthermore, we introduce a re-mapping for
ultra-wide angles which would otherwise lead to wrong motion compensation
results for the fisheye boundary. Both concepts extend an existing hybrid
motion estimation method for equisolid fisheye video sequences that decides
between traditional and fisheye block matching in a block-based manner.
Compared to that method, the proposed calibration and re-mapping extensions
yield gains of up to 0.58 dB in luminance PSNR for real-world fisheye video
sequences. Overall gains amount to up to 3.32 dB compared to traditional block
matching.
