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
[email protected]
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