Method and apparatus for estimating a camera reference horizon

A computer program product for generating a camera reference horizon estimate Ŷ0, the computer program product comprising means, residing on a computer-readable medium, for:

• receiving a sequence of images including projections of objects thereon, with projections including horizontal edges;
• estimating vertical motion occurring in the sequence of images and storing the estimated vertical motion as a motion history;
• computing the projection of the horizontal edges in the images;
• segmenting the projected horizontal edges in the images;
• compensating for motion in the images using the estimated vertical motion from the motion history;
• tracking the projections of the horizontal edges from image to image to generate tracks representing objects and maintaining an active track storage by adding more data to update the active track storage from each subsequent image;
• screening the generated tracks using screening criteria to produce a subset of tracks in order to enhance track reliability;
• receiving the subset of tracks from the means for screening and estimating distances to the objects represented by the tracks and heights of the objects represented by the tracks;
• further screening the subset of tracks by calculating an error criteria for each track and selecting a subset of remaining tracks satisfying the error criteria;
• and
• generating a camera reference horizon estimate Ŷ0 from the remaining tracks.

An apparatus for generating a camera reference horizon estimate Ŷ0, the apparatus comprising:

• a memory for storing data and processing results;
• a processor operationally coupled with the memory, the processor including means for receiving a sequence of images including projections of objects thereon, with projections including horizontal edges, the processor including means for performing operations thereon, for:
• estimating vertical motion occurring in the sequence of images and storing the estimated vertical motion as a motion history;
• computing the projection of the horizontal edges in the images;
• segmenting the projected horizontal edges in the images;
• compensating for motion in the images using the estimated vertical motion from the motion history;
• tracking the projections of the horizontal edges from image to image to generate tracks representing objects and maintaining an active track storage by adding more data to update the active track storage from each subsequent image;
• screening the generated tracks using screening criteria to produce a subset of tracks in order to enhance track reliability;
• receiving the subset of tracks from the means for screening and estimating distances to the objects represented by the tracks and heights of the objects represented by the tracks;
• further screening the subset of tracks by calculating an error criteria for each track and selecting a subset of remaining tracks satisfying the error criteria;
• and
• generating a camera reference horizon estimate Ŷ0 from the remaining tracks.