Joaquim, For .tar.gz, you can use /vsitar
Mike -- Michael Smith Remote Sensing/GIS Center US Army Corps of Engineers Hanover, NH On 3/24/11 2:03 PM, "Joaquim Luis" <jl...@ualg.pt> wrote: > Even, Chaitanya > > Thanks for hint. > > I did read the http://trac.osgeo.org/gdal/wiki/UserDocs/ReadInZip but it > hasn't any mention to the need of using "vsicurl" > > I was about to do the tests you did, so thank you also for that. > The point here is not to read that file in particular. I just wanted to > use one as example and one that is not a *.tar.gz that the docs say it > won't work. > Ok, I have enough information to make it possible to read some > compressed files sitting somewhere in the web and have the data land > directly in the internals of GMT. > > Thanks > > Joaquim > >> Joaquim, >> >> The correct syntax would be : >> >> gdalinfo >> /vsizip/vsicurl/http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90 >> .dem.zip/W020N90.DEM >> >> or just : >> >> gdalinfo >> /vsizip/vsicurl/http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90 >> .dem.zip >> >> because the zip file only contains one single file (W020N90.DEM) >> >> ... But the W020N90.DEM inside the zip file isn't directly recognized by GDAL >> (even if you download it and unzip the file). It's just a RAW file, that >> neads >> an header to tell the dimension, georeferencing, datatype etc, so the above >> won't directly work. >> >> You can for example create a VRT that refers to the raw file : >> >> <VRTDataset rasterXSize="4800" rasterYSize="6000"> >> <GeoTransform>-20, 8.3333333333300008e-03, 0, 90, 0, >> -8.3333333333300008e-03</GeoTransform> >> <VRTRasterBand dataType="Int16" band="1" subClass="VRTRawRasterBand"> >> <NoDataValue>-9999</NoDataValue> >> <SourceFilename >> relativetoVRT="0">/vsizip/vsicurl/http://dds.cr.usgs.gov/srtm/version2_1/SRTM >> 30/w020n90/w020n90.dem.zip</SourceFilename> >> <ByteOrder>MSB</ByteOrder> >> </VRTRasterBand> >> </VRTDataset> >> >> I've deduced this VRT from the >> http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90.hdr.zip file >> that >> sits next to the .dem.zip file. >> >> It's a shame that they didn't put the .hdr and the .dem file inside the same >> zip. It would have they been possible to open it directly... >> >> With the SRTM3 in HGT format, you can directly do : >> >> gdalinfo >> /vsizip/vsicurl/http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/Africa/N00E006.h >> gt.zip >> >> Best regards, >> >> Even >> >>> Hi, >>> >>> How do we access to a compressed files by URL? We can do that, can't we? >>> >>> As an example I try this (on Windows) >>> >>> gdalinfo >>> /vsizip/C:\http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90.de >>> m.zip ERROR 4: >>> `/vsizip/C:\http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90.d >>> em.zip' does not exist in the file system, >>> and is not recognised as a supported dataset name. >>> >>> and this >>> >>> gdalinfo >>> /vsizip//http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/w020n90/w020n90.dem. >>> zip >>> >>> but the error message is similar. >>> >>> The idea is to fetch the data directly into GMT, but first I need to >>> understand well how it works. >>> >>> Thanks >>> >>> Joaquim Luis >>> _______________________________________________ >>> gdal-dev mailing list >>> gdal-dev@lists.osgeo.org >>> http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
