Target-independent algorithms for description and structural matching of aerospace photographs
Vadim R. Lutsiv, Igor A. Malyshev, Vadim Pepelka, Alexey S. Potapov · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
The aim of investigation was developing the registration algorithms for the aerial and cosmic pictures taken in different seasons from differing viewpoints, formed by differing kinds of sensors (visible, IR, SAR). Structural matching was chosen as the only approach that could manage with the mentioned image differences. In the contrast to the target dependent structural analysis applied in the expert systems we dealt with the images of arbitrary content, thus the rigidity and opacity of landscape objects and the rules of shadowing were the only limitations applied. The simple contour elements corresponding to the objects borders were judged to be a most stable source of structural descriptions in this uncertain situation. However a large amount of similar simple elements produced a high dimensional structural matching task. It decreased the reliability of matching and exponentially increased the computational expenditures. We solved this problem building the hierarchical structural descriptions. We separated the structural elements to the rather small local groups and structurally matched them using the special tree walking algorithms. Two grouping approaches were applied: uniting the elements belonging to a continuous contour line, or uniting the ones situated in a separate compact region. The matching results were reliable both for the multiple season and multiple sensor images. The first approach demonstrates a slightly better precision, while the second one is slightly more robust and flexible, thus it can deal also with the structural elements of other nature: the compact regions formed in result of texture segmentation were also successfully structurally matched.