[Gdal-dev] GIO format

[Frank Warmerdam]

Gao wrote:
> GIO is listed as one of the supported formats, but I can't find it
> in my installation (built from gdal-1.2.3 source). What do I need to
> do get this driver? 

Peng,

It should call the registration function by default, but the registration
function only registers the driver if various entry points can be successfully
found in avgridio.dll or aigridio.dll.  If those aren't in the path is just
quietly ignores the driver.

The second thing I would mention is that while avgridio.dll (the grid module
from ArcView 3.x) was advertised for use with some docs on the web, the
same was never (seemingly) true of the ArcGIS version (aigridio.dll) and I
never really got this working properly.  I think it has something to do with
things not being properly initialized in advance, though I'm not sure.

Thirdly, the GIO driver support for writing grids with avgridio.dll never
worked quite right because of my after-writing hack to update the georeferencing.
So I don't advise people to use gio for writing grids.  And really, the
AIG driver seems just as good at reading grids as the GIO one is, and the
AIG driver has less risks related to try and use a DLL out of another package.

So, if you want to write grids, I should really look at reworking the GIO
driver to support "once through writes" so that I have the georeferencing
information at creation time.  Also, if you were interested we could look
into getting the GIO driver working with aigridio.dll from ArcGIS, but I
think you would have better resources for looking into the issues with that
than I have.

Best regards,
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