[OSGeo-Standards] [Fwd: [Geotools-devel] ImageIO MetaData]

[Martin Desruisseaux]

Simone point out a lot of our difficulties with GridCoverage in his
email. I share his view on most of the points he raise, especially the
following ones (I'm really not adding anything new; Simone said all):

Le vendredi 07 septembre 2007 à 20:35 +0200, Simone Giannecchini a
écrit :
> The bad news is that, IMHO, the situation is not improved over the
> time, well to be honest I think things are getting more intricate,
> since new documents are coming up during the time.

This is sadly true. The overlaps area between OGC specifications
(especially the one related to GridCoverage) seems to be increasing with
time, sometime in a coherent way, sometime not. The following list is
not even exaustive...

  - ISO 19123
  - Grid Coverage Implementation Specification
  - The Coverage Type
  - Earth Imagery
  - Imagery Metadata
  - Image CRS for IH4DS
  - GML 3.1.1 Grid CRS profile
  - GML in JPEG 2000
  - GML encoding of discrete coverage
  - Grid Coverage Service
  - Web Coverage Service
  - Web Coverage Processing Service
  - Image Exploitation Service
  - Image Coordinate Transformation Service




> 1>A lot of documents, as I said, refer to ISO 19123 implicitly while,
> afaik at least, GridCoverage IS is still THE adopted specification for
> GridCoverage, afaik at least.

True as far as I know...


> 2>ISO 19123 is not available for free, hence this can be a show
> stopper for people(I know it is not expensive but still, many OGC
> documents are referring to an ISO specification that you are supposed
> to pay for. (Well, IMHO, this is quite strange, what does Open stand
> for in the acronym OGC? :-) ).

A few years ago, every OGC specifications were really freely available.
But OGC was kind of competiting with ISO. They merged their work (which
is fine), but maybe on the basis of some misunderstanding, OGC started
to publish ISO specifications for free on their web site. ISO 19107,
19111 and 19115 were freely downloadable from OGC web site for instance.
ISO complained about that. OGC tried to talk to ISO and apparently
failed to convince them to give their specification for free. ISO 19107
among other had to be removed from OGC free download area.

So my feeling is that OGC was in good faith and really wanted to give
the specifications for free, but did not managed to get a deal with ISO
as they think they could. I may be completly wrong, it is just a
feeling. But I admit that this is a problem for us...


> Well ISO19123 does NOT propose anything about I/O or processing
> itself. There might be other ISO specs, I admit my ignorance about
> this

True, and I'm not aware of any ISO specification for coverage I/O and
processing neither...


> 5>While ISO 19123 seems to focus only on a model for Coverage it is
> much more complex than the old GridCoverage IS hence it is not so
> attractive at first given also what I said above, at least IMHO :-).

Very true again... I had a very hard time trying to understand ISO
19123, and this part is still omitted from the GeoAPI changes I wanted
to submit to OGC because I still not sure that I understood it right. I
do not expect a full ISO 19123 implementation in Geotools for a while...

Thanks Simone for you effort in trying to provide some light in this
Grid Coverage jungle...

    Martin