[gdal-dev] [PROPOSAL] Add CADRG write support via RPFTOC/NITF drivers

[Patrik Sylve]

Hi,

We are exploring the possibility of adding write support for CADRG format in GDAL and would appreciate some community feedback before starting implementation.

There is currently no open-source workflow for creating CADRG. GDAL can already read CADRG via RPFTOC/NITF drivers, so extending that work feels like a good next step.


Short background on CADRG format:

CADRG is a Raster Product Format (RPF) that consists of a TOC file referencing data frames. Each data frame is stored as a National Imagery Transmission Format (NITF) message.

GDAL currently supports:

* Reading CADRG (a.toc) via the RPFTOC driver
* Reading individual CADRG frames via the NITF driver
* Writing NITF images, both without and with JPEG compression


To implement a CADRG writer, we could extend the existing NITF and RPFTOC drivers:

NITF:
* Implement Vector Quantisation compression
* Add option to set Frame size
** A CADRG frame must be 1536x1536 pixels, so output would be tiled
* Add option to set CADRG scale

RPFTOC:
* Extend with 'write' mode
** Internally call NITF driver to generate CADRG compliant data frames
** Generate a .toc file per MIL-STD-2411

Example usage, create a CADRG from a TIF-file:

gdal_translate input.tif ./RPF \
    -of RPFTOC \
     -co "PRODUCT=CADRG" \
    # NITF file header options
    -co "FTITLE=My CADRG Product" \
    -co "FSCLAS=U" \
         ...

Output:
└── RPF/
├─── a.toc
└─── frames/
├──── 00AVL01C.TL6
└──── 00AVM01C.TL6



Drivers:
* https://gdal.org/en/stable/drivers/raster/rpftoc.html
* https://gdal.org/en/stable/drivers/raster/nitf.html

Standards:
* CADRG: http://everyspec.com/MIL-PRF/MIL-PRF-080000-99999/MIL-PRF-89038_25371/
* RPF: http://everyspec.com/MIL-STD/MIL-STD-2000-2999/MIL-STD-2411_6903/


Would this be a welcomed addition? Any thoughts or feedback is appreciated.



Best regards / Vänliga hälsningar


Patrik Sylve

Software Developer


E: patrik.sylve at t-kartor.com


www.t-kartor.com<http://www.t-kartor.com/>


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