RelateOp producing incorrect DE-9IM Matrix

[gleng]

It seems like geos::operation::relate::RelateOp does not respect the specified curve boundary rule when given LineStrings whose bounding boxes are disjoint, and instead uses the default Mod2 rule. If the bounding boxes intersect, the specified curve boundary rule will be correctly used.

I have attached a modified example.cpp that demonstrates the issue in GEOS 3.8.1. It can be easily run by replacing the example.cpp file located in the doc folder.

I have also tested this in PostGIS and seen the same behaviour.

[gleng]

Here are the queries needed to show this behaviour in PostGIS. The first three queries produce the correct DE-9IM matrix, but the last query does not.

Correctly Produces FF1FFF1F2:
SELECT ST_Relate(ST_GeometryFromText('LINESTRING(0 0, 1 2, 2 0, 0 0)'), ST_GeometryFromText('LINESTRING(1.5 1.5, 2.5 3.5, 3.5 1.5, 1.5 1.5)'),1);

Correctly Produces FF1FF0102:
SELECT ST_Relate(ST_GeometryFromText('LINESTRING(0 0, 1 2, 2 0, 0 0)'), ST_GeometryFromText('LINESTRING(1.5 1.5, 2.5 3.5, 3.5 1.5, 1.5 1.5)'),2);

Correctly Produces FF1FFF1F2:
SELECT ST_Relate(ST_GeometryFromText('LINESTRING(0 0, 1 2, 2 0, 0 0)'), ST_GeometryFromText('LINESTRING(3 3, 4 5, 5 3, 3 3)'),1);

Incorrectly Produces FF1FFF1F2 (expect FF1FF0102):
SELECT ST_Relate(ST_GeometryFromText('LINESTRING(0 0, 1 2, 2 0, 0 0)'), ST_GeometryFromText('LINESTRING(3 3, 4 5, 5 3, 3 3)'),2);

[robe]

Retargeting in prep for GEOS 3.10.0 release