[Qgis-user] Clipping tool takes a lot of time

[Jonas Sjögren]

Hi,
to check that my data was ok I tried a clip tool in ArcMap where the same
calcuation took exactly 10 seconds. After some modifications in my script
and using the 'qgis:difference' algorithm, processing time was reduced to
about 5 minutes, quite acceptable. Thank you for helping me sort this out.
/Jonas

2014-10-14 7:47 GMT+02:00 Bernhard Ströbl <bernhard.stroebl at jena.de>:

> Hm,
>
> goes pretty fast here, both with PostGIS and shp layers (some 5 lines, 1
> polygon, both layers in the same CRS as the project, shp on local drive)
> QGIS 2.4 64 bit on Win7
>
> Bernhard
>
> Am 14.10.2014 02:49, schrieb Mike Flannigan:
>
>
>> I am also using QGIS 2.4 64b Chugiak on Windows 7.
>> The same thing happens to me.  Even when I create
>> a line layer with only 11 lines and try to clip 3
>> of them with a polygon layer, the progress bar just
>> goes back and forth for ever.
>>
>> I didn't run it for hours to see what would eventually
>> happen.
>>
>> Mike
>>
>>
>> I might be doing something wrong.
>>
>> On 10/13/2014 8:02 AM, qgis-user-request at lists.osgeo.org wrote:
>>
>>> Hi,
>>> I am trying to clip a road network by a polygon in a script using the
>>> algorithm 'qgis:clip'. The result seems to be quite ok but it takes an
>>> incredible long time to produce, about 14 hours (!). The road network
>>> shapefile consists of about 5000 features (not very many, I believe) and
>>> the clipping shapefile consists of one single polygon. When using
>>> Vector =>
>>> Geoprocessing Tools => Clip from the QGIS menu, the time required is
>>> about
>>> the same. Does anyone have a clue why it takes so long time? Are there
>>> other clip tools that I may try? I?ve been looking at the
>>> 'gdalogr:ogr2ogr'
>>> algorithm and its clipsrc function but not got it to work properly
>>> yet. I?m
>>> using QGIS 2.4 Chugiak on Windows 7 with 2.5 GHz processor. Thankful for
>>> all hints that may help,
>>> /Jonas
>>>
>>
>>
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