[gdal-dev] Using MEM driver to output to an gtiff in /vsimem/

[Bborie Park]

On 03/29/2011 03:17 PM, Bborie Park wrote:
> Hi,
>
> What I'm attempting to do is write some code to do the following:
>
> PostGIS Raster -> GDAL MEM -> user specified GDAL output format in
> /vsimem/ (e.g. GTiff) -> return contents of the output file to user
>
> I'm able to successfully create a MEM dataset with raw band data
> specified using the DATAPOINTER creation option and the GDALRasterIO()
> function from a PostGIS Raster. I've been successful outputting the MEM
> dataset using CreateCopy() to a GTiff stored on the filesystem (e.g.
> /tmp/out.tif), such as...
>
> rtn_ds = GDALCreateCopy(
> rtn_drv,
> "/tmp/out.tif",
> src_ds,
> FALSE,
> options,
> NULL,
> NULL
> );
>
> What does not seem to work is if I use CreateCopy with a /vsimem/ path.
>
> rtn_ds = GDALCreateCopy(
> rtn_drv,
> "/vsimem/out.tif",
> src_ds,
> FALSE,
> options,
> NULL,
> NULL
> );
>
> rtn = VSIGetMemFileBuffer("/vsimem/out.tif", &j, FALSE);
>
> When I read /vsimem/out.tif back out to pass back to the end-user, the
> contents are significantly shorter than what it should be. From what I
> can tell, the contents outputted are just the tiff header information
> and none of the band data.
>
> Is there something different about outputting a raster to a filesystem
> rather than /vsimem/ when working with a MEM raster with external band
> data?
>
> Thanks,
> Bborie
>

Sorry all.  One hour after I sent the prior email, I add a 
GDALFlushCache() and everything works. *sigh*

-bborie

-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu