[Qgis-developer] Re: [Qgis-user] SEXTANTE - using calculator tools from SAGA and GRASS

Victor Olaya volayaf at gmail.com
Fri May 4 13:43:08 PDT 2012


Thanks for your help

The resampling is automatically done, so you can use layers that do
not match (which cannot be done in saga). However, if grids do match,
maybe I should implement some mechanism to avoid the resampling.

Let me test those layers and I will tell you what is going on, ok?

Thanks again!

2012/5/4 Pedro Venâncio <pedrongvenancio at yahoo.com>:
> Hi,
> Some new observations I've made.
> In the example I used yesterday, the raster input was float32.
> I tested now with a Int16 raster input and found that the problems are even greater. On one hand, the rasters are coming out of the Grid Calculator float32. Secondly, the extent is always changed, and the resample is always applied, irrespective of whether an odd or even number of layers.
> Screencast: http://goo.gl/A1ccn
> Using the SAGA GUI, the rasters are also converted to float32, but the Extent is preserved and the resample is not applied.
> Screencast: http://goo.gl/ZJhnv
> I did these tests on Windows 7 and Debian Wheezy, with the same results.
> If someone wants to try to replicate, the original data are from FaunaliaPT and Professor Gonçalves from University of Porto.
> http://www.faunalia.pt/downloads/mdt_aster_pt-tm06_GeoTIFF.tar.gz
> http://www.fc.up.pt/pessoas/jagoncal/srtm/dem_srtm_pttm06_80m.tif.bz2
> Best regards,
> Pedro Venâncio

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