[Qgis-user] QGis/Grass - slow Vector export

Thomas Wahlmüller thomas.wahlmueller at gmx.net
Tue Mar 22 01:47:32 PDT 2011


Hi

Tanks for your help...

> Have you tried by simply "Save as.."?
Thanks I didn't know I can export GRASS-Vector via QGIS this way.

>> By the way: I needed to convert a Raster to Point, because I had
>> Artefacts (stripes of lower height-value) after reprojection with GDAL.
>> Are there any other solutions?
> 
> r.resamp?

I think it's not clear what i have done.

With artefacts:
QGIS: reproject Raster with gdal-warp (from MGI/Austria Lambert (EPSG
32287) to WGS84/UTM32N (EPSG 32633))
GRASS: import reprojected Raster
GRASS: I also had to resample the raster (cell size changed because of
reprojection from 10m to 10.012m)

In both rasters (reprojects, resampled) the error is visible with
hillshade in GRASS


clean of artefacts:
GRASS --> Load Raster, convert Raster to Points
GRASS --> reproject Points (I was able to find out, how to reproject in
grass, so didn't needed the vector export in the end)
GRASS --> interpolate Points to 10m-Raster

I also tested r.proj now - and it is also clean of artefacts

have a nice day and thanks for your help
thomas



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