[gdal-dev] Support for reading GDAL datasets in compressed archives (.gz and .zip)

[Lucena, Ivan]

Rouault,

Nice job!

Even Rouault wrote:
> ----------------------------------
> To read from a .gz file,
> ----------------------------------
> gdalinfo /vsigzip/path/to/the/file.gz were path/to/the/file.gz is relative or 
> absolute.
> 
> The first time that a .gz file is read, a small .gz.properties file will be 
> generated (if possible) to capture the uncompressed data size. This will make 
> following opening of that dataset much faster.

Suggestion:

Would be interesting to bring the content of "file.gz" as subdatasets:

Subdatasets:
   SUBDATASET_1_NAME=/vsizip/myarchive.zip/subdir1/file1.tif
   SUBDATASET_1_DESC=GeoTiff,100x110x1
   SUBDATASET_2_NAME=/vsizip/myarchive.zip/subdir1/file2.tif
   SUBDATASET_2_DESC=GeoTiff,100x110x1
   SUBDATASET_3_NAME=/vsizip/myarchive.zip/subdir1/file3.tif
   SUBDATASET_3_DESC=GeoTiff,100x110x1

What do you think?

> Small syntaxic sugar : if the .zip file contains only one file located at its 
> root, just mentionning "/vsizip/path/to/the/file.zip" will work.

The same would apply to subdatasets, I guess.

> The fact that this new capability is implemented as virtual file systems imply 
> that it will only work for GDAL drivers supporting the "large file API". A 
> list of such drivers is : PNG, JPEG, ILWIS, GTiff, GIF, JP2KAK, NITF, ADRG, 
> DTED, SRTMHGT, BMP, LCP, HFA (Erdas Imagine), AAIGRID. Other drivers may work 
> too (I just looked for those advertizing the GDAL_DCAP_VIRTUALIO capability)

That all we need? Nice!

Best regards,

Ivan