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Get rid of some tests in _ST_ConcaveHull and only attempt to make a polygon if the line is simple. ST_Covers is causing me quite a bit of greif as a testing tool. don't recall so many topo node this and that in GEOS 3.2 ST_Covers. Also add in some regress tests for ST_ConcaveHull -- more to come.
git-svn-id: http://svn.osgeo.org/postgis/trunk@7006 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Regina Obe
parent
e1c23bbf5c
commit
3cc1d00614
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@ -5087,23 +5087,26 @@ CREATE OR REPLACE FUNCTION ST_MinimumBoundingCircle(geometry)
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-- Contributed by Regina Obe and Leo Hsu
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-- Availability: 2.0.0
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-----------------------------------------------------------------------
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CREATE OR REPLACE FUNCTION _ST_ConcaveHull(param_inputgeom geometry)
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CREATE OR REPLACE FUNCTION _st_concavehull(param_inputgeom geometry)
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RETURNS geometry AS
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$$
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DECLARE
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vexhull GEOMETRY;
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var_resultgeom geometry;
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var_inputgeom geometry;
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vexring GEOMETRY;
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cavering GEOMETRY;
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cavept geometry[];
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seglength double precision;
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var_tempgeom geometry;
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scale_factor integer := 1;
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i integer;
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BEGIN
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-- First compute the ConvexHull of the geometry
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vexhull := ST_ConvexHull(param_inputgeom);
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var_inputgeom := param_inputgeom;
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--A point really has no concave hull
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IF ST_GeometryType(vexhull) = 'ST_Point' OR ST_GeometryType(vexHull) = 'ST_LineString' THEN
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RETURN vexhull;
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@ -5111,6 +5114,12 @@ $$
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-- convert the hull perimeter to a linestring so we can manipulate individual points
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vexring := CASE WHEN ST_GeometryType(vexhull) = 'ST_LineString' THEN vexhull ELSE ST_ExteriorRing(vexhull) END;
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IF abs(ST_X(ST_PointN(vexring,1))) < 1 THEN --scale the geometry to prevent stupid precision errors - not sure it works so make low for now
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scale_factor := 100;
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vexring := ST_Scale(vexring, scale_factor,scale_factor);
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var_inputgeom := ST_Scale(var_inputgeom, scale_factor, scale_factor);
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--RAISE NOTICE 'Scaling';
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END IF;
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seglength := ST_Length(vexring)/least(ST_NPoints(vexring)*2,1000) ;
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vexring := ST_Segmentize(vexring, seglength);
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@ -5119,7 +5128,7 @@ $$
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ARRAY(
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SELECT
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ST_ClosestPoint(param_inputgeom, pt ) As the_geom
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ST_ClosestPoint(var_inputgeom, pt ) As the_geom
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FROM (
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SELECT ST_PointN(vexring, n ) As pt, n
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FROM
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@ -5129,34 +5138,27 @@ $$
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)
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)
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;
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var_resultgeom := ST_MakePolygon(ST_MakeLine(geom))
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FROM ST_Dump(cavering) As foo;
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IF NOT ST_IsValid(var_resultgeom) THEN
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--RAISE NOTICE '_ST_Concavehull invalid %', ST_AsText(var_resultgeom);
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var_tempgeom := ST_BuildArea(var_resultgeom); -- try to make valid
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IF NOT ST_IsValid(var_tempgeom) THEN
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var_resultgeom := ST_Buffer(var_resultgeom,ST_Length(cavering)/1000, 'quad_segs=3'); -- try to make valid
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END IF;
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--if still invalid or doens't contain the geometry just return convex hull
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IF NOT ST_IsValid(var_resultgeom) or ST_GeometryType(var_resultgeom) <> 'ST_Polygon' THEN
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var_resultgeom := ST_ConvexHull(param_inputgeom);
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ELSIF ST_GeometryType(param_inputgeom) ILIKE '%Geometry%' THEN
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IF EXISTS(SELECT geom FROM ST_Dump(param_inputgeom) WHERE NOT ST_Covers(var_resultgeom,geom) ) THEN
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--we have to explode inputgeom since geos doesn't support geometrycollections for containment check
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var_resultgeom := ST_ConvexHull(param_inputgeom);
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END IF;
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ELSIF NOT ST_Contains(var_resultgeom, param_inputgeom) THEN
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var_resultgeom := ST_ConvexHull(param_inputgeom);
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END IF;
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var_resultgeom := ST_MakeLine(geom)
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FROM ST_Dump(cavering) As foo;
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IF ST_IsSimple(var_resultgeom) THEN
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var_resultgeom := ST_MakePolygon(var_resultgeom);
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--RAISE NOTICE 'is Simple: %', var_resultgeom;
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ELSE /** will not result in a valid polygon -- just return convex hull **/
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--RAISE NOTICE 'is not Simple: %', var_resultgeom;
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var_resultgeom := ST_ConvexHull(var_resultgeom);
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END IF;
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IF scale_factor > 1 THEN -- scale the result back
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var_resultgeom := ST_Scale(var_resultgeom, 1/scale_factor, 1/scale_factor);
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END IF;
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RETURN var_resultgeom;
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END;
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$$
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LANGUAGE 'plpgsql' IMMUTABLE STRICT
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COST 100;
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LANGUAGE plpgsql IMMUTABLE STRICT;
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CREATE OR REPLACE FUNCTION ST_ConcaveHull(param_geom geometry, param_pctconvex float, param_allow_holes boolean) RETURNS geometry AS
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$$
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@ -86,7 +86,8 @@ TESTS = \
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tickets \
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remove_repeated_points \
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split \
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relate
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relate \
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concave_hull
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# TESTS += wmsservers_old
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42
regress/concave_hull.sql
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42
regress/concave_hull.sql
Normal file
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@ -0,0 +1,42 @@
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-- $Id$
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-- Tests to confirm the concave hull area is <= convex hull and
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-- covers the original geometry (can't use covers because always gives topo errors with 3.3
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SELECT
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'ST_ConcaveHull MultiPolygon 0.95', ST_Area(ST_Intersection(geom,ST_ConcaveHull(
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geom, 0.95) )) = ST_Area(geom) As encloses_geom,
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(ST_Area(ST_ConvexHull(geom))
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- ST_Area(ST_ConcaveHull(geom, 0.95))) < (0.95 * ST_Area(ST_ConvexHull(geom) ) ) As reached_target
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FROM ST_Union(ST_GeomFromText('POLYGON((175 150, 20 40,
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50 60, 125 100, 175 150))'),
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ST_Buffer(ST_GeomFromText('POINT(110 170)'), 20)
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) As geom;
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SELECT
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'ST_ConcaveHull Lines 0.80', ST_Intersection(geom,ST_ConcaveHull(
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geom, 0.80) ) = geom As encloses_geom,
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(ST_Area(ST_ConvexHull(geom))
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- ST_Area(ST_ConcaveHull(geom, 0.80))) < (0.80 * ST_Area(ST_ConvexHull(geom) ) ) As reached_target
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FROM ST_GeomFromText('MULTILINESTRING((106 164,30 112,74 70,82 112,130 94,
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130 62,122 40,156 32,162 76,172 88),
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(132 178,134 148,128 136,96 128,132 108,150 130,
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170 142,174 110,156 96,158 90,158 88),
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(22 64,66 28,94 38,94 68,114 76,112 30,
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132 10,168 18,178 34,186 52,184 74,190 100,
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190 122,182 148,178 170,176 184,156 164,146 178,
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132 186,92 182,56 158,36 150,62 150,76 128,88 118))') As geom;
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-- test holes vs. no holes - holes should still enclose but have smaller area than no holes --
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SELECT
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'ST_ConcaveHull Lines 0.80 holes', ST_Intersection(geom,ST_ConcaveHull(
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geom, 0.80, true) ) = geom As encloses_geom,
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ST_Area(ST_ConcaveHull(geom, 0.80, true)) < ST_Area(ST_ConcaveHull(geom, 0.80)) As reached_target
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FROM ST_GeomFromText('MULTILINESTRING((106 164,30 112,74 70,82 112,130 94,
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130 62,122 40,156 32,162 76,172 88),
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(132 178,134 148,128 136,96 128,132 108,150 130,
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170 142,174 110,156 96,158 90,158 88),
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(22 64,66 28,94 38,94 68,114 76,112 30,
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132 10,168 18,178 34,186 52,184 74,190 100,
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190 122,182 148,178 170,176 184,156 164,146 178,
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132 186,92 182,56 158,36 150,62 150,76 128,88 118))') As geom;
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3
regress/concave_hull_expected
Normal file
3
regress/concave_hull_expected
Normal file
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@ -0,0 +1,3 @@
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ST_ConcaveHull MultiPolygon 0.95|t|t
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ST_ConcaveHull Lines 0.80|t|t
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ST_ConcaveHull Lines 0.80 holes|t|t
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