The Stages of Construction
1) Visual information is gathered by recognition of intensity differences.
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2) A two-dimensional primal sketch is made, which orders visual information into a representation of edges and other surface details.
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3) From that primal sketch a 2-and-one-half sketch is constructed to include depth and movement features of the physical surfaces of the object.
4) Finally, the 2-and-one-half dimensional sketch is compared with other stored two-and-one-half dimensional sketches.
The result is a three-dimensional structural description with a hierarchical structure.
David Marr and Keith Nisihara, 1982. |