[gdal-dev] Creating modified copies of a file

[Cole, Derek]

Right, I can do this for my already opened and read-from data set. However, I want to have a separate file. This means I have to copy that original data set, right? I can't seem to figure out how to copy a data set without actually copying the raster data (which is huge in comparison to the meta). Are you suggesting I just add another band to the already opened file? Not entirely sure I like this approach, but it may be doable.

Derek
________________________________
From: Chaitanya kumar CH [chaitanya.ch at gmail.com]
Sent: Tuesday, July 05, 2011 1:35 PM
To: Cole, Derek
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] Creating modified copies of a file

Derek,

Writing into a raster band is a lot like reading into it. Use the function you use to read the pixels to write the pixels back.
Don't forget to close the dataset at the end using GDALClose() [1]. Also, check out the GDALFlushCache() and similar functions in [2].

[1]: http://www.gdal.org/gdal_8h.html#0984222d45a72028fcbbf1f44831ffbc
[2]: http://www.gdal.org/gdal_8h.html

On Tue, Jul 5, 2011 at 9:16 PM, Cole, Derek <dcole at integrity-apps.com<mailto:dcole at integrity-apps.com>> wrote:
Hello,

I think I started to ask about this before on this forum, but I have since used GDAL a bit more and might be better to generate a new thread.

I have been using GDAL to read in NITF files, getting the RasterBand data, and manipulating it, and displaying the results in my viewer.

Now, I would like to be able process data, then save it into a new NITF. This new NITF will have the same geocoords and all of the same data as the original, with the exception of a new raster band replacing the original. Is there a way to create a clone of the original image WITHOUT copying the data? I do not want to have to replicate the old data on disk, only the overwrite it with my new data that is coming from the external processing. I looked into creating the virtual data sets, but I am not sure if that is my answer. If I just pass in an empty "" as the destination, it says it will create that dataset in memory. Is this what I want to do?

My algorithm processes only a portion of the image at a time, so what I envisioned in my head was being able to essentially write out header /meta information in a file, and "append" blocks of raster data into the right place in the file, as they complete processing. This way there is no single lag-point while waiting to create a copy of data on disk to another place on disk, or having to create a large file on disk all at once. These image files are 1GB+

Any tips for trying to set up this scenario?

Thanks

Derek

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