[gdal-dev] Arc File Geodatabase

[Richard Barnes]

I saw a posting from July 
<https://lists.osgeo.org/pipermail/gdal-dev/2016-July/044761.html> about 
work towards deciphering the Arc File Geodatabase Raster format.

Inspired, I did some work today and successfully extracted a raster from 
a geodatabase.

Using Even Rouault's /dump_gdbtable/ as a starting point, I decompressed 
the raster blobs using zlib, as suggested in the posting.

For my raster, this gave 128x128 big-endian 32-bit floating-point values 
with a trailer of about 512 bytes.

Assembling these 128x128 tiles using the col_nbr and row_nbr fields 
resulted in the raster coming out.

I've uploaded my fork, along with appropriate input data and a command 
to run it all (see README.md) to https://github.com/r-barnes/dump_gdbtable.

What remains is to link metadata (block size, band_width, band_height) 
to the raster so the output can be sized appropriately, the data type 
deduced automatically, and projections saved. This is probably just a 
matter of linking the appropriate rows from some of the lower-numbered 
gdbtables with the files containing the raster data. It might also be 
nice to determine whether zlib is always being used, but I assume an 
error could be thrown if an unexpected compression format is encountered.

I'm interested in seeing GDAL include the ability to translate Arc File 
Geodatabase Rasters into other (less proprietary) formats.
What is a good way to move forward with that?

Best regards,
Richard Barnes
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