FA-70435 / GIS polygon topology / Member archive
DE-9IM matrix named predicate evaluation: overlaps equal dimension guard · case 05
A line lying partly inside a polygon is reported as overlapping it.
Case contract
Input [matrix, predicate, dimA, dimB] with a 9-character intersection matrix over "F012" (row-major II, IB, IE, BI, BB, BE, EI, EB, EE). Pattern characters: "*" anything, "T" any non-F value, "F" only F, "0"/"1"/"2" that exact dimension. disjoint = FF*FF****; intersects = not disjoint; touches (not both points) = FT******* or F**T***** or F***T****; within = T*F**F***; contains = T*****FF*; covers = any of T*****FF*, *T****FF*, ***T**FF*, ****T*FF*; overlaps needs equal dimensions and 1*T***T** for lines else T*T***T**; crosses = T*T****** if dimA < dimB, T*****T** if dimA > dimB, 0******** for two lines, otherwise false; equals = T*F**FFF*. Unknown predicates return None.
Why this case matters
Spatial SQL predicates, topology rules and QA checks are expressed as DE-9IM patterns; a wrong pattern changes join results silently.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| control #33 | true | false | Failed |
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