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<DIV dir=ltr align=left><SPAN class=184074520-17092007>[ Carl Reed gave me
permission to forward the below note to this list. He also notes that "
the dialogue has begun thanks to some OGC members who participate in the osgeo
community" and that "the group needs to know that 19123 will shortly be an OGC
abstract spec document that will be publicly and freely available. Should be
available starting after Sept 21st." ]</SPAN></DIV><!-- Converted from text/rtf format -->
<P><SPAN lang=en-us>-mpg</SPAN> </P>
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<FONT face=Tahoma size=2><B>From:</B> <A
href="mailto:coverages.wg-bounces+mpg=lizardtech.com@opengeospatial.org">coverages.wg-bounces+mpg=lizardtech.com@opengeospatial.org</A>
[mailto:coverages.wg-bounces+mpg=lizardtech.com@opengeospatial.org] <B>On
Behalf Of </B>Carl Reed OGC Account<BR><B>Sent:</B> Thursday, September
13, 2007 3:58 PM<BR><B>To:</B> wcs.rwg@opengis.org;
coverages.wg@opengeospatial.org<BR><B>Subject:</B> Re: [Coverages.wg]
OSGeo email WRT OGC and coverage remail standards<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>I thought that the following might be of interest to the OGC members
involved with coverages and imagery. Just underscores the need for a
simple, well defined, well documented easy to implement interface with
potentially an implementation primer associated with it.</DIV>
<DIV> </DIV>
<DIV>Hate to harp on this issue, but the open source world appears to have
increasing implementation experience with coverages and their experience
with OGC and ISO approaches has not been overly successful. </DIV>
<DIV> </DIV>
<DIV>Perhaps a dialogue with the appropriate folks in that community might
be in order.</DIV>
<DIV> </DIV>
<DIV>Regards</DIV>
<DIV><BR>Carl</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>my bad the document did not float around from the start, I think
there<BR>was a misunderstanding between me, Martin and Daniele. But let's
put<BR>things in context :-).<BR><BR><A bit of history first for
whoever may be interested. ><BR><BR>Since I started working with OGC
standards more or less 3.5 years ago<BR>I noticed that while there was an
adopted Grid Coverage Implementation<BR>Specification many other documents
where implicitly referring to ISO<BR>19123.</DIV>
<DIV><BR>I also felt not comfortable with the fact that there were/are
so many<BR>different discussion papers/abstract
specifications/implementation<BR>specification and so on trying to come up
with a way to<BR>encode/model/represent GridCoverage metadata, like
georeferencing,<BR>quality metadata, usage metadata, sensor model
metadata, etc....<BR>The bad news is that, IMHO, the situation is not
improved over the<BR>time, well to be honest I think things are getting
more intricate,<BR>since new documents are coming up during the
time.<BR><BR>To summarise, the problems I see:<BR><BR>1>A lot of
documents, as I said, refer to ISO 19123 implicitly while,<BR>afaik at
least, GridCoverage IS is still THE adopted specification
for<BR>GridCoverage, afaik at least.<BR><BR>2>ISO 19123 is not
available for free, hence this can be a show<BR>stopper for people(I know
it is not expensive but still, many OGC<BR>documents are referring to an
ISO specification that you are supposed<BR>to pay for. (Well, IMHO, this
is quite strange, what does Open stand<BR>for in the acronym OGC? :-)
).<BR><BR>3>GridCoverage IS was made of mainly 3 parts (as far as I can
remember<BR>at least :-) )<BR> - GridCoverageExchange
that proposes a model for I/O<BR> - GridCoverageProcessor that
proposes a model for GridCoverage Processing<BR> -
GridCoverage that proposes a model for GridCoverage<BR><BR>Well ISO19123
does NOT propose anything about I/O or processing<BR>itself. There might
be other ISO specs, I admit my ignorance about<BR>this, but I also admit
that I do not want to get into the Dependency<BR>Graph of ISO specs which
could cost me a few thousands Euros :-).<BR><BR>So the problem here is
that it apparently seems that the new de-facto<BR>standard for
GridCoverages is ISO19123 but the latter covers a<BR>smaller area
than GC IS. How are are we supposed to I/O and<BR>processing? (as I said
other specs may be involved, no idea yet).<BR><BR><BR>4>While
GridCoverage IS make a shy attempt to deal with metadata, ISO<BR>19123
leave the thing mostly aside. Is it good, is it bad? Not
sure...<BR>Probably metadata should be handled somewhere else but I
don't think<BR>the situation can be improved just leaving
asides.<BR><BR><BR>5>While ISO 19123 seems to focus only on a model for
Coverage it is<BR>much more complex than the old GridCoverage IS hence it
is not so<BR>attractive at first given also what I said above, at least
IMHO :-).<BR><BR>There may be more, but I don't want to get you bored
(maybe I alredy did it...)<BR><BR><Why this document><BR>In the
GeoTools/GeoServer community there has been a lot of discussion<BR>about
how to "handle" multidimensional GridCoverages<BR>(t,z,band,level,y,x). A
lot of documents were produced (let me mention<BR>the wonderful documents
that Bryce Nordgren wrote) with many good<BR>ideas but given lack of
time/resources (and probably bad project<BR>managing?) not much was
produced.<BR><BR>During the last months two different efforts are going on
in order to<BR>produce something useful. GeoSolutions has received a
mandate to<BR>investigate these problems and come up with a first
solutions from<BR>NURC and other partners while Geomatys received a
similar mandate from<BR>IFREMER.<BR>Since both companies make money out of
GeoTools and GeoServer we<BR>thought it would have been nice to cooperate.
This is the good part.<BR>The bad part is that we have different deadlines
and programs hence we<BR>are trying to not step on each other's feet and
concentrate on<BR>different aspects of the same problems while still
trying to<BR>synchronize.<BR>This document is supposed to be (at least in
my dreams :-) ) what<BR>keeps us synchronized and in the end it should
also try to make<BR>proposals on how to correct the problem I pointed out
above. We<BR>probably may not succeed, but at least we tried! :-).<BR>It
comes out of sparse note I have written in the past, but is
has<BR>undergone multiple reviews from Daniele, Alessio Fabiani and
other<BR>people. Since a couple of weeks we have started to share it
with<BR>Martin as well.<BR><BR><BR><Conclusion><BR>There might be
more to say but I am about to go running on the seaside<BR>hence time for
conclusions.<BR>My idea was to start circulate the pdf in the geotools
community and<BR>then put the pdf of the document somewhere (suggestions?)
in order to<BR>have people look at it ( right now it is under our svn).
For the<BR>moment I would restrict the write permission to me, Daniele,
Alessio<BR>and Martin because this is not simply a theoretical proposal,
as I<BR>said it captures ongoing work we are doing along with proposal
for<BR>next steps, hence I think we should put some control on it. However
I<BR>am open to loose up this control a bit (suggestions?
Ideas?).<BR><BR>Ciao a tutti,<BR>Simone.<BR><BR>PS<BR>Sorry, the email is
too
long.<BR>==================================================================================</DIV>
<DIV>Carl Reed, PhD<BR>CTO and Executive Director Specification
Program<BR>OGC</DIV>
<DIV> </DIV>
<DIV>The OGC: Helping the World to Communicate Geographically</DIV>
<DIV> </DIV>
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