Opened 3 years ago

Closed 3 years ago

Last modified 3 years ago

#4015 closed defect (invalid)

ST_Covers may have bug

Reported by: petermj Owned by: pramsey
Priority: medium Milestone: PostGIS 2.4.4
Component: postgis Version: 2.4.x
Keywords: Cc:

Description

The following code produces (for me) unexpected results.

I have a large and a small tile (square polygon), and I believe the large should cover the small, but as a geography is does not, and as a geometry it does?

The tiles share a corner point, and the neighbouring corners share either longitude or latitude.

SELECT
ST_Covers(large.tile, small.tile),
ST_Covers(large.tile::geography, small.tile::geography)
FROM
	(SELECT 'POLYGON((-3.34216155333235 55.3991017765333,-3.34058316886567 55.3991017765333,-3.34058316886567 55.4,-3.34216155333235 55.4,-3.34216155333235 55.3991017765333))'::geometry as tile) as large,
	(SELECT 'POLYGON((-3.34216155333235 55.3999101776593,-3.34200371488568 55.3999101776593,-3.34200371488568 55.4,-3.34216155333235 55.4,-3.34216155333235 55.3999101776593))'::geometry as tile) as small
                 
;

I'm happy to be told my knowledge of GIS is incomplete and this is a standard newbie error, but it felt wrong to my mind....?

Change History (3)

comment:1 Changed 3 years ago by petermj

Sorry, I forgot to add I get the answer:

true, false

comment:2 Changed 3 years ago by pramsey

Resolution: invalid
Status: newclosed

Does this help?

Version 0, edited 3 years ago by pramsey (next)

comment:3 Changed 3 years ago by petermj

Thank you very much I was suspecting this as much.

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