[gdal-dev] Creating modified copies of a file

[Cole, Derek]

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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