Am 22.01.2016 um 10:52 schrieb Ari Jolma:
22.01.2016, 10:06, Kai Muehlbauer kirjoitti:
To quickly check if there is an improvement I used the python shapely
package. Converting the outer loop geometry to an shapely prepared
geometry and calling 'contains()' with the inner loop geometries to
find those fully contained geometries I get an improvement of nearly
40% to the former ogr only code.
As Even pointed out, there is only OGRPreparedGeometryIntersects()
(GEOSPreparedIntersects) exposed within ogrgeometry.cpp. In my use
case I would need GEOSPreparedContains to mimic the shapely behaviour.
I made a small test with the attached diff, which prepares the
geometries of the input layer.
The input layer had two polygons (boundaries of two Finnish
municipalities) and the method layer had 3091 points, all in either one
of the polygons.
The improvement is ~15%.
I think the prepared geometries could be used by default easily.
Prepared contains test would need addition of the respective GEOS method.
Thanks Ari, I very much appreciate your efforts in testing layer
intersection. If the prepared contains test could be done within the
layer intersection then those features can "just be copied" without the
need of costly intersection calculation. This would give a real speedup.
So, it would need the addition of the OGRPreparedGeometryContains method
(GEOSPreparedContains) and then enhancing your patch.
Would it work the way as in the attached diff? Or did I miss something?
What are the next steps to get this feature fully implemented?
Cheers,
Kai
--- ogrlayer.cpp 2015-09-15 16:06:45.000000000 +0200
+++ ogrlayer.cpp 2016-01-22 11:45:42.955096518 +0100
@@ -2050,6 +2050,7 @@
if (ret != OGRERR_NONE) goto done;
poDefnResult = pLayerResult->GetLayerDefn();
bEnvelopeSet = pLayerMethod->GetExtent(&sEnvelopeMethod, 1) == OGRERR_NONE;
+ int bUsePreparedGeometries = CPLTestBool(CSLFetchNameValueDef(papszOptions, "USE_PREPARED_GEOMETRIES", "NO"));
ResetReading();
while (OGRFeature *x = GetNextFeature()) {
@@ -2093,10 +2094,33 @@
continue;
}
+ //
+ OGRPreparedGeometry* x_prepared_geom = NULL;
+ if (bUsePreparedGeometries) x_prepared_geom = OGRCreatePreparedGeometry(x_geom);
+
pLayerMethod->ResetReading();
while (OGRFeature *y = pLayerMethod->GetNextFeature()) {
OGRGeometry *y_geom = y->GetGeometryRef();
if (!y_geom) {delete y; continue;}
+
+ if (bUsePreparedGeometries &&
+ ((x_prepared_geom && OGRPreparedGeometryContains(x_prepared_geom, y_geom)) ||
+ x_geom->Contains(y_geom)))
+ {
+ OGRGeometry* poIntersection = y_geom;
+ }
+ else
+ {
+ if (bUsePreparedGeometries &&
+ !((x_prepared_geom && OGRPreparedGeometryIntersects(x_prepared_geom, y_geom)) ||
+ x_geom->Intersects(y_geom)))
+ {
+ delete y;
+ continue;
+ }
+ OGRGeometry* poIntersection = x_geom->Intersection(y_geom);
+ }
+
OGRGeometry* poIntersection = x_geom->Intersection(y_geom);
if( poIntersection == NULL || poIntersection->IsEmpty() ||
(x_geom->getDimension() == 2 &&
@@ -2119,6 +2143,7 @@
delete z;
if (ret != OGRERR_NONE) {
if (!bSkipFailures) {
+ OGRDestroyPreparedGeometry(x_prepared_geom);
delete x;
goto done;
} else {
@@ -2129,6 +2154,7 @@
}
}
+ OGRDestroyPreparedGeometry(x_prepared_geom);
delete x;
}
if (pfnProgress && !pfnProgress(1.0, "", pProgressArg)) {
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