FA-70545 / GIS polygon topology / Member archive

Hole placement validation against shell and siblings: shell contact allowance · case 05

Holes that touch the shell at a vertex are rejected as outside.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input [shell, holes], closed integer rings. Point classification against a ring: on an edge = 0, inside by half-open crossing number = 1, else -1. For each hole in order: "outside" if any hole vertex is strictly outside the shell; else "coincident" if every hole vertex lies on the shell boundary; else "nested" if for some OTHER hole all its vertices are inside-or-on that hole and at least one is strictly inside; else "ok". Return one label per hole.

Why this case matters

Polygon validity rules require holes to lie inside the shell and not inside each other; mislabelled holes block valid data or let invalid parcels through.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression #2	`["outside"]`	`["ok"]`	Failed

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