Descriptor matching and Lowe's ratio test
WHAT IT TESTS: robust feature matching. OUTLINE: match by nearest-neighbor descriptor distance; Lowe's ratio test keeps a match only if the best is clearly better than the second-best, rejecting ambiguous ones.
WHAT IT TESTS: how to filter unreliable matches. ANSWER OUTLINE: for each descriptor in image one you find its nearest neighbors in image two by distance. Lowe's ratio test compares the closest and second-closest distances; if their ratio exceeds a threshold (around 0.7-0.8) the match is ambiguous and discarded. It works because a correct match should be distinctly closer than any other candidate, while a wrong match in a repetitive region has several near-equal candidates. RED FLAG: relying on a single absolute distance threshold.
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- #feature-matching
- #lowes-ratio-test
- #nearest-neighbor
- #descriptors
- #outlier-rejection
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