[gdal-dev] CreateCopy() with same metadata, different raster data

[Cole, Derek]

What about using the VRT driver? Is that for the situation I am describing? According to the CreateCopy documentation:

It is intended that CreateCopy() will often be used with a source dataset which is a virtual dataset allowing configuration of band types, and other information without actually duplicating raster data (see the VRT driver). This is what is done by the gdal_translate utility for example.

And according to the first example of Programatic creation of VRT datasets on http://www.gdal.org/gdal_vrttut.html

This looks like it creates clone of everything but the raster data. Can I basically do this when I am loading my image for the first time, then when my outputs are ready, open this, create a copy using the NITF driver, and then write to the bands of the NITF driver using RasterIO?

Thanks

Derek
________________________________________
From: gdal-dev-bounces at lists.osgeo.org [gdal-dev-bounces at lists.osgeo.org] on behalf of Frank Warmerdam [warmerdam at pobox.com]
Sent: Wednesday, June 15, 2011 10:44 AM
To: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] CreateCopy() with same metadata, different raster data

On 11-06-14 09:18 PM, Cole, Derek wrote:
> Hrmm, that is sort of unfortunate. I have set up a tiling algorithm to read
> in tiles at a time of imagery data, which is already slow-ish, even doing it
> it with threads. Having to do a whole new read of the entire image at once
> (since it doesnt seem CreateCopy takes any block parameters) would be pretty
> time consuming.
>
> Am I better off trying to just copy the Dataset manually, creating a new
> file from that?

Derek,

If efficiency is important, and you have a limited amount of metadata
you need to copy, I would setup your imagery in memory as a MEM dataset
and then programatically copy the parts of the metadata you need to it
from the source file.  Then do a CreateCopy from that to your final file.

You can ee something like that done in C in the MapServer msSaveImageGDAL()
function at:

   http://trac.osgeo.org/mapserver/browser/trunk/mapserver/mapgdal.c#L152

In all this I am assuming your final format is one that only supports
CreateCopy() (like JPEG or PNG) otherwise you can just imperatively
create the output file and set the info on it after writing the imagery.

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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