QGIS » QGIS Application

Confirmed, and causes a complete freeze here.

Hi Agus,
are for any instance this data 3d vectors (like exported from geomedia)?

I don't why I set this as blocker as it is not a regression.

I developed a simple plugin in c++ that try to do the same thing that tool points in polygon does. But I have no success (in a reasonable time) in the iterating process over all polygons, answering how many points has inside in each polygon.

I logged, in a csv file, the following debug output: (I check the geometry validity, if it's not valid I put on log file the line "#invalid")

inGeom->wkbType()
inGeom->length()
inGeom->area()
polygonVertex( polyFeat ) [number of vertices in polygon)
pointList.size() [number of points returned by spatial index query giving the polygon bounding box]
count [number of points that really intersects the polygon]
timer.nsecsElapsed() [nanoseconds since that current polygon started to be processed]

I am not sure if the attached log can help in the attempts to solve this issue.

The test plugin is accessible in:

https://bitbucket.org/danielvaz/mixed-ideas/src/2bc94814ebc03d66ded69375dd35c4d023c013d7/qgis/points_in_polygon?at=master

Thanks in advance

vinayan Parameswaran wrote:

the polygon layer contains quite a lot of invalid geometries(around 300 of them)..try a check geometry validity using topology checker..without fixing these errors, there is no point in running a PIP on this layer..I think we are wasting our time on this layer by keeping this bug..otherwise a complex layer with clean geometry should be added for testing..

Hi Vinayan,
while you are right about geometry errors in general, I think this is kind of a "special" case, as the reported errors are all about different nodes of a same feature that do touch each other (see attached image). While I believe this is considered in general an error, we must also consider that when vectorizing (raster to vector) it is almost sure to get such "errors", and it is common to use such resulting vectors in further geoprocessing operations. We must also consider that other tools (like SAGA/SEXTANTE) are able to handle such feature while doing this operation.

We probably can lower the priority of the ticket because there is now an alternative (SEXTANTE), but for sure something we may want to improve, or not :)

Giovanni Manghi wrote:

vinayan Parameswaran wrote:

the polygon layer contains quite a lot of invalid geometries(around 300 of them)..try a check geometry validity using topology checker..without fixing these errors, there is no point in running a PIP on this layer..I think we are wasting our time on this layer by keeping this bug..otherwise a complex layer with clean geometry should be added for testing..

Hi Vinayan,
while you are right about geometry errors in general, I think this is kind of a "special" case, as the reported errors are all about different nodes of a same feature that do touch each other (see attached image). While I believe this is considered in general an error, we must also consider that when vectorizing (raster to vector) it is almost sure to get such "errors", and it is common to use such resulting vectors in further geoprocessing operations. We must also consider that other tools (like SAGA/SEXTANTE) are able to handle such feature while doing this operation.

I do not think we can consider these as errors (I attach the error layer produced by "Check geometry validity" ), just as characteristics of the layer: "Check geometry validity" is (wrongly I think) reporting as errors the cases in which 2 polygons share 1 single vertex, why should those be considered as errors? I think the problem is rather that ftools has not taken this case into account, and this could be the reason why it fails (and the reason why the plugin works for a test polygon derived from a rectangular grid, where no polygons sharing one single vertex exist).

We probably can lower the priority of the ticket because there is now an alternative (SEXTANTE), but for sure something we may want to improve, or not :)

I would agree, but "Counts points in polygon" in Sextante fails also (1.9.0-Master QGIS code revision 1847c61,
"Traceback (most recent call last):
File "/Users/agustinlobo/.qgis//python/plugins/sextante/core/GeoAlgorithm.py", line 145, in execute
self.processAlgorithm(progress)
File "/Users/agustinlobo/.qgis//python/plugins/sextante/algs/ftools/PointsInPolygon.py", line 76, in processAlgorithm
spatialIndex = utils.createSpatialIndex(pointLayer)
File "/Users/agustinlobo/.qgis//python/plugins/sextante/algs/ftools/FToolsUtils.py", line 32, in createSpatialIndex
provider = layer.provider()
AttributeError: 'QgsVectorLayer' object has no attribute 'provider'"

So there is no option.

The main issue with the attached layer are the few huge geometries, especially the one with ID 26569 - with more than two thousand of holes and 90 thousand of vertices, it is a very complex polygon. There are about eight thousand of points that need to be tested for intersection, each of the tests takes ~1 second on my computer... so the computation would take few hours, but eventually will end.

This can be improved, though. I have done few tests with "prepared geometry" functionality from GEOS (>= 3.1) and that makes HUGE difference - the computation was done within few seconds. I have raised feature request #9521 to implement that.

Therefore I am closing this ticket (there is no bug, the computation just takes long time)