[gdal-dev] Intersection of two Layers

[Kai Muehlbauer]

Am 22.01.2016 um 13:26 schrieb Even Rouault:
> Le vendredi 22 janvier 2016 13:19:40, Kai Muehlbauer a écrit :
>> Am 22.01.2016 um 12:58 schrieb Ari Jolma:
>>> 22.01.2016, 13:49, Kai Muehlbauer kirjoitti:
>>>> This is very good news! If I understand correctly, I could use your
>>>> patch and self-compile gdal to have access to the improved
>>>> layer-intersection function via the python bindings. I'll give this a
>>>> try.
>>>
>>> Attached is probably a bit better diff.
>>>
>>> As I wrote, similar thing should be done for other layer methods.
>>>
>>> Yes, you can use this with the trunk version.
>>
>> Thanks Ari, I keep you posted. If I get this running, I'm also available
>> for testing the other changes.
>
> Kai, just thinking: do you have spatial indices defined, especially on the
> method layer ? If not, that would be the first thing to do since for each
> geometry in input layer, a spatial filter is set on method layer using the
> extent of the input geometry.

Thanks for the comment Even, yes, I have a spatial filter in place. But 
with prepared geometries it takes only 50% of the time. Attached you 
find my (stripped) python code:

Method 1 is more or less what I do. In my example this takes 35 seconds.

Method 2 I implemented with shapely prepared geometry. This runs only 
~17 seconds on the same machine.

If I call layer.Intersection(method, dst, options) directly it takes ~55 
seconds.

So with the prepared geometries we get 70% improvement. And 50% 
improvement compared to the iteration over layer method.

And, without SpatialFilter this will run almost forever.

Thanks again for your comments, it's very much appreciated.

Cheers,
Kai