Use spatial index to check shell nesting in IsValidOp #256
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This commit introduces a IndexedNestedShellTester class, modelled after IndexedNestedRingTester, to check shell nesting as part of MultiPolygon validity checking. Indexes are used both to locate rings relative to each other (STRtree) and to check point containment within a ring (IndexedPointOnAreaLocator). This commit reduces GEOSisValid runtime for a test geometry (GADM boundary of Australia) from about 85 seconds to less than 1 second. It does not appreciably change runtime for TIGER counties, HydroBASINS Level 5, or a sample parcel dataset.
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Wow, nice performance bump. This is relevant to MultiPolygons with large numbers of element Polygons, right? |
Yes. Australia sees such a huge benefit because it has so many islands that have to be tested against the highly-complex shell for the mainland. |
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This PR introduces an
IndexedNestedShellTesterclass, modelled afterIndexedNestedRingTester, to check shell nesting as part of MultiPolygonvalidity checking. Relevant methods are yanked out of
IsValidOpthen updated to use indexes to locate rings relative to each other
(STRtree) and to check point containment within a ring
(IndexedPointOnAreaLocator).
You need the right geometry for this to matter.
This commit reduces GEOSisValid runtime for a test geometry (GADM
boundary of Australia) from about 85 seconds to less than 1 second. It
does not appreciably change runtime for TIGER counties, HydroBASINS
Level 5, or a sample parcel dataset.