[gdal-dev] Strange errors with large vrt

[yvecai]

On 10/09/2012 08:45 PM, Even Rouault wrote:
> Did you check that there was no error or warning reported when 
> building the VRT ? 
There is no warning from gdalbuiltvrt, is there a flag for a verbose mode?

> What do you mean by "I don't have any data" ? Do you mean that if you 
> do an extraction from that VRT, you get no significant data ? 
If I make a crop with gdal_translate I only have a hillshade from the 
areas originating from SRTM, but not from the Aster areas. The result of 
gdal_translate is empty above 61°N.
Obviously this could come from the fact I used to distinct step to 
generate hillshade files for SRTM and then for Aster, but I can't see no 
differences between them ??

> What does gdalinfo report on the generated VRT ? Does it reported 
> extent goes above 60° ? 
Should be ok:

    Corner Coordinates:
    Upper Left  (-20037508.316,17822038.826) (180d 0' 0.00"W, 83d 0' 0.50"N)
    Lower Left  (-20037508.316,-11402298.645) (180d 0' 0.00"W, 71d 0'
    0.28"S)
    Upper Right (20037428.628,17822038.826) (179d59'57.42"E, 83d 0' 0.50"N)
    Lower Right (20037428.628,-11402298.645) (179d59'57.42"E, 71d 0' 0.28"S)
    Center      (     -39.844, 3209870.091) (  0d 0' 1.29"W, 27d41'21.83"N)


>> Maybe someone can see a difference between hillshade2_N58E164.tif and
>> hillshade2_N63E164.tif ? See gdalinfo below, I don't.
> I don't see any difference... But all the files you provided in the archive are
> definitely odd : their first band is set to 0. Only the 2nd band (alpha band=
> has non uniform data. So that might explain what you saw with the huge .vrt
This is intended to build a hillshade overlay for webmaps, hence the 
black + alpha.
>> Also, vrt files and some tiles can be found at
>> http://www.pistes-nordiques.org/download/extract.zip (16MB).
> No VRT files in that zip.
http://www.pistes-nordiques.org/download/small.vrt
http://www.pistes-nordiques.org/download/big.vrt

Yves
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20121009/3e002670/attachment.html>