[postgis-devel] ST_OffsetCurve : hitting precision limit to soon

Rémi Cura remi.cura at gmail.com
Thu Nov 7 00:42:02 PST 2013


Hey Dear List,

Some showcase of strange ST_OffsetCurve Behavior :
It returns completely wrong output, even if far from double precision limit
(3 to 6 digits remaining).
As a proof seconf image show 1k points with the min spacing possible with
double precision limit

DROP TABLE IF EXISTS test_1 ;
CREATE TABLE test_1 AS
SELECT 1,ST_OffsetCurve(ST_GeomFromText('LINESTRING(1000001000 1000001000
,11000001000 1100001000)'),0.01)
UNION
SELECT 2, ST_OffsetCurve(ST_GeomFromText('LINESTRING(1000001000 1000001000
,11000001000 1100001000)'),-0.01)
UNION
SELECT 3,ST_GeomFromText('LINESTRING(1000001000 1000001000 ,11000001000
1100001000)');

image : http://hpics.li/66442f1
image : http://hpics.li/1ae01f8


Cheers,
Rémi-C
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