FA-70367 / GIS polygon topology / Member archive

Ring vertex cleaning with snapping tolerance: tolerance inclusivity · case 02

Vertices exactly one tolerance away from the previous vertex survive cleaning.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Input [ring, eps] where ring is an open or closed list of integer [x, y] positions and eps >= 0. Walk the ring and drop a position whose Chebyshev distance to the last KEPT position is <= eps. Then repeatedly drop trailing kept positions within eps of the first kept position. If fewer than 3 positions remain return None, else return the kept positions closed by repeating the first.

Why this case matters

Digitised boundaries carry jitter and duplicate clicks; cleaning must not let small steps accumulate into dropped corners or leave near-closing duplicates.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
control #3	`[[64, 69], [62, 67], [54, 72], [44, 80], [43, 82], [38, 76], [36, 75], [22, 74], [13, 56], [12, 42], [64, 69]]`	`[[64, 69], [54, 72], [44, 80], [38, 76], [22, 74], [13, 56], [12, 42], [64, 69]]`	Failed

MEMBER ARCHIVE

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