Perceiving 3D from 2D Images

Automatic Labeling

Finding a legal labeling can be done by:

1. tree search with backtracking when a node is inconsistent

2. Waltz filtering or discrete relaxation

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Initialize the label set for each line segment to {+,-,>,<}

At each iteration, remove inconsistent labels as follows

If L is a label for edge Pi and there is another edge Pj

connected to Pi that has no label consistent with L,

then remove L from the label set of Pi.