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

[Peter Baumann]

Hi all,

just saw this, thought I'd chime in being the editor of GMLCOV :)
Any questions, I'll gladly try to answer, I'm just on the road currently, so 
expect a delay of a day or so.

Trying to respond to what has been raised below:

On 05/12/2014 11:18 PM, Even Rouault wrote:
> Le lundi 12 mai 2014 23:05:21, Jukka Rahkonen a écrit :
>> Even Rouault <even.rouault <at> mines-paris.org> writes:
>>
>> ...
>>
>>>> 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.
>> What GMLJP2 gives as a bonus is the axis order trouble

actually, no. GMLJP2 relies on GMLCOV which defines axis order. Each coverage 
has a Native CRS which is defined via an OGC URI (which, in the case of EPSG, 
refers to the OGP maintained database). In the CRS definition the axis is given 
unambiguously.

If you don't want to go to that database, use the axisLabels attribute in the 
Envelope, it lists axes in their proper sequence.


>> and not totally
>> clear interpretation if origin is in the centre (probably it is) or in the
>> corner of a pixel,

naively, GMLCOV follows the pixel-in center interpretation. However, encodings 
may override this, such as GeoTIFF (see the pertaining adopted spec [1]).

[1] https://portal.opengeospatial.org/files/?artifact_id=50118


>> and rectified grid does not support ground control
>> points.

yes, because it is rectified. If you want more degree of freedom do not use 
RectifiedGridCoverage but ReferenceableGridCoverage. In conjunction with GML 3.3 
( a compatible enhancement of GML 3.2.1) this gives you irregular and warped 
grids. We're not completely done, though, and would be glad about your support 
in some advanced issues. Note that this work is all voluntary and relies on some 
project financing to be done. Up to now, EC and ESA have been generous, and so 
we are going ahead step by step.


>> Thus GMLJP2 is at least not better in everything, it has also
>> drawbacks.
> Hi Jukka,
>
> Yes, for all your above reasons, I would prefer to avoid it.

so which ones are remaining, following the clarification you mention below?

cheers,
Peter

> Although the axis order trouble (the one of EPSG) and interpretation of origin
> (pixel center) should be mostly clarified with the revised version.
> As far as ground countrol points are concerned, I've not really looked at the
> capabilities of GMLCov, so perhaps there's something in it for that.
> Otherwise, that would be indeed a drawback.
>
>> -Jukka Rahkonen-
>>
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-- 
Dr. Peter Baumann
  - Professor of Computer Science, Jacobs University Bremen
    www.faculty.jacobs-university.de/pbaumann
    mail: p.baumann at jacobs-university.de
    tel: +49-421-200-3178, fax: +49-421-200-493178
  - Executive Director, rasdaman GmbH Bremen (HRB 26793)
    www.rasdaman.com, mail: baumann at rasdaman.com
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