Le jeudi 18 septembre 2014 17:40:11, Peter Hopfgartner a écrit : > Hi, everybody > > we are using the GDAL WMS driver for getting maps from a public WMTS > service, http://www.basemap.at. Anyway, the resulting image does not > look smooth. In particular, I would guess that the the image was scaled > with something like a nearest neighbor algorithm. > So my question is simply, if I can switch the interpolation method in > some place. > > The XML file, taken from > http://gisforge.wordpress.com/2012/11/06/basemap-at-wmts-layer-in-qgis/, > is: > > <GDAL_WMS> > <Service name="TMS"> > <ServerUrl>http://maps.wien.gv.at/basemap/geolandbasemap/normal/google3857/ > ${z}/${y}/${x}.jpeg</ServerUrl> </Service> > <DataWindow> > <UpperLeftX>-20037508.34</UpperLeftX> > <UpperLeftY>20037508.34</UpperLeftY> > <LowerRightX>20037508.34</LowerRightX> > <LowerRightY>-20037508.34</LowerRightY> > <TileLevel>18</TileLevel> > <TileCountX>1</TileCountX> > <TileCountY>1</TileCountY> > <YOrigin>top</YOrigin> > </DataWindow> > <Projection>EPSG:3857</Projection> > <BlockSizeX>256</BlockSizeX> > <BlockSizeY>256</BlockSizeY> > <BandsCount>3</BandsCount> > <Cache /> > </GDAL_WMS> > > The command is: > > gdal_translate -srcwin 35500000 23500000 100000 100000 -of JPEG -outsize > 250 250 basemap_at.xml basemap_at.jpg
Peter, Resampling done by gdal_translate is nearest neighbour, so not always that great. What you can do is select an outsize that is compatible with the source overviews. In TMS, the ratio between sucessive overviews work with factor of 2, so you should select an outsize of 10000 / 2^N. The closest is 10000 / 256 = 390.625 -> 391 So gdal_translate -srcwin 35500000 23500000 100000 100000 -outsize 391 391 basemap_at.xml tmp.tif and then: gdalwarp tmp.tif tmp2.tif -r lanczos -ts 250 250 (you can try different resampling kernel) gdal_translate tmp2.tif basemap_at.jpg -of JPEG Best regards, Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
