Diffuse interreflections cause effects that make current theories of shape from shading unsatisfactory. We show that distant radiating surfaces produce radiosity effects at low spatial frequencies. This means that, if a shading pattern has a small region of support, unseen surfaces in the environment can only produce effects that vary slowly over the support region. It is therefore relatively easy to construct matching processes for such patterns that are robust to interreflections. We call regions with these patterns "shading primitives". Folds and grooves on surfaces provide two examples of shading primitives; the shading pattern is relatively independent of surface shape at a fold or a groove, and the pattern is localised. We show that the pattern of shading can be predicted accurately by a simple model, and derive a matching process from this model. Both groove and fold matchers are shown to work well on images of real scenes.


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    Title :

    Shading primitives: finding folds and shallow grooves


    Contributors:
    Haddon, J. (author) / Forsyth, D. (author)


    Publication date :

    1998-01-01


    Size :

    779592 byte




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



    Shading Primitives: Finding Folds and Shallow Grooves

    Haddon, J. / Forsyth, D. / IEEE; Computer Society | British Library Conference Proceedings | 1998



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