PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual106 / 310ExamplesSELECT ST_IsValid(ST_GeomFromText(’LINESTRING(0 0, 1 1)’)) As good_line,ST_IsValid(ST_GeomFromText(’POLYGON((0 0, 1 1, 1 2, 1 1, 0 0))’)) As bad_poly--resultsNOTICE: Self-intersection at or near point 0 0good_line | bad_poly-----------+----------t| fSee AlsoST_IsSimple, ST_IsValidReason, ST_Summary7.4.16 ST_IsValidReasonST_IsValidReason — Returns text stating if a geometry is valid or not and if not valid, a reason why.Synopsistext ST_IsValidReason(geometry geomA);DescriptionReturns text stating if a geometry is valid or not an if not valid, a reason why.Useful in combination with ST_IsValid to generate a detailed report of invalid geometries and reasons.Availability: 1.4 - requires GEOS >= 3.1.0.Examples--First 3 Rejects from a successful quintuplet experimentSELECT gid, ST_IsValidReason(the_geom) as validity_infoFROM(SELECT ST_MakePolygon(ST_ExteriorRing(e.buff), ST_Accum(f.line)) As the_geom, gidFROM (SELECT ST_Buffer(ST_MakePoint(x1*10,y1), z1) As buff, x1*10 + y1*100 + z1*1000 As gidFROM generate_series(-4,6) x1CROSS JOIN generate_series(2,5) y1CROSS JOIN generate_series(1,8) z1WHERE x1 > y1*0.5 AND z1 < x1*y1) As eINNER JOIN (SELECT ST_Translate(ST_ExteriorRing(ST_Buffer(ST_MakePoint(x1*10,y1), z1)),y1 ←↪*1, z1*2) As lineFROM generate_series(-3,6) x1CROSS JOIN generate_series(2,5) y1CROSS JOIN generate_series(1,10) z1WHERE x1 > y1*0.75 AND z1 < x1*y1) As fON (ST_Area(e.buff) > 78 AND ST_Contains(e.buff, f.line))GROUP BY gid, e.buff) As quintuplet_experimentWHERE ST_IsValid(the_geom) = falseORDER BY gidLIMIT 3;gid | validity_info------+--------------------------5330 | Self-intersection [32 5]