[gdal-dev] Idea: GeoTIFF box in JPEG to add georeferencing

[Robert Coup]

On Tue, May 13, 2014 at 7:59 AM, Even Rouault <even.rouault at mines-paris.org>
 wrote:

> >
> > In light of this, it may be better to use an xml or textual
> representation
> > and embed it inside an XMP block, which is supported for many formats[1].
> > Also it would allow for easier human-reading.
>
> Yes, that's one possibility. Which comes back to GMLJP2 unless there are
> other
> standards...
>
> I'd want to build on something that is a "real" standard or a de-facto
> standard, but not reinvent everything from scratch.
>

While embedding a GeoTIFF inside a JPEG file is straightforward for GDAL, I
would think that doesn't apply to a random implementation (eg. libjpeg) who
wants to support geo-information. But then I learn that EXIF (from what I
can tell) is implemented as a TIFF file stored within the JPEG, so any JPEG
libraries that support EXIF already support TIFF tags.

In terms of "be native", EXIF seems like the right approach to do this,
with a "Geo" IFD alongside "Image" or "GPSInfo", maybe using exactly the
same set of tags as GeoTIFF.

GMLJP2 is arguably more comprehensive and has the benefit of (in theory)
improving on GeoTIFF, but I haven't actually used it in depth, and Jukka
already mentioned missing GCP support.

2c, didn't really get to a conclusion though

Rob :)
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