I created a table of ST_ClosestPoint()s to polylines. I assumed that if the closest points were on the line the queries below would give equal results, but that's not happening.
"InsideWorking".simplified is a line.
"gaps".closeststartpoint is a point.
SELECT "gaps".closeststartpoint FROM "gaps"
WHERE "gaps".closeststartpoint IS NOT NULL; --Query produces 462 results.
SELECT * FROM "gaps","InsideWorking"
WHERE ST_Covers("InsideWorking".simplified,"gaps".closeststartpoint);
--Query produces 1228 results.
SELECT * FROM "gaps","InsideWorking"
WHERE ST_Contains("InsideWorking".simplified,"gaps".closeststartpoint);
--Query produces 548 results.
SELECT "gaps".closeststartpoint FROM "gaps","InsideWorking"
WHERE ST_Touches("InsideWorking".simplified,"gaps".closeststartpoint);
--Query produces 680 results.
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SELECT "gaps".closeststartpoint FROM "gaps","InsideWorking"
WHERE ST_DWithin("InsideWorking".simplified,"gaps".closeststartpoint,0);
--Query produces 1258 results.
Inspection shows the ST_DWithin() query is getting better results than the
other queries. So I think I've got something that works, but I'd appreciate
some advice on why the others don't give similar results.
Thanks in advance.
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