[gdal-dev] gdalbuildvrt

Frank Warmerdam warmerdam at pobox.com
Thu Feb 3 13:59:39 EST 2011


On 11-02-03 01:30 PM, Aníbal Pacheco wrote:
> Hi, I'm using gdalbuildvrt to produce a virtual raster layer which can then
> used in Mapnik and its ogcserver(WMS), everything works except that the result
> image is black & white and with a very poor resolution. The 2 source tif files
> used in this test were both colored with a good resolution. Any ideas?


Aníbal,

I would suggest examining the resulting vrt to see if there is anything
odd about it.  Start with gdalinfo to see if it's resolution seems reasonable
and if in fact it is 3 bands.  You might want to run "gdalinfo -stats xx.vrt"
to get band statistics just to verify that the bands are radiometrically
distinct.  Also, check that the band pixel type is reasonable - the same
as the source files.

If that all looks ok, then perhaps visually examine the VRT with something
like QGIS.

After that it comes down to talking to Mapnik people about why there are
problems.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent



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