[Seavox] Sea Area Thesaurus

Mon May 4 11:20:01 BST 2009

Hi Michele,

The objective of C19 is to use SeaVoX governance to overcome some of the difficulties that IHO governance has encountered moving S23 on from its 1953 version due to repreated vetos over the naming of Sea of Japan.  It is based on the latest IHO proposals with some extensions that have been requested, such as extension to include freshwater bodies.

C19 is largely a superset of C16, but there are some cases where the relationship between C16 and C19 isn't perfectly clean.  This is because I have followed IHO, who decided that some areas required more extensive modification than others.  I have a mapping between C16 and C19 prepared by Greg Read, which I will load up into the server at some stage.  Inevitably because of the way IHO have done things this will be more complex than pure synonyms.

I have deliberately hedged the issue of multi-lingual naming for the present.  I have three options open to me.  One is the kludge used in some versions of IHO I have seen with a second language in brackets such as English Channel (La Manche).  I don't like this because it implies that the French is a second class alternative to the English.  Secondly, I could add entries for other languages and map them as synonyms.  However, this means that the code for La Manche would be different to English Channel, which could cause problems for tools that aren't clever enough to realise the two are mapped.  The third is to investigate other technological solutions and adopt something appropriate - I particularly like the way Gemet handles languages.  This is my preferred option, but needs work.  If NETMAR gets funded then that work should get done.  So, for now I prefer to wait.

In the current implementation of C19 the maximum code length is 8 and the maximum name length is 55 bytes.  I very much doubt if the code limit will be exceeded, but the name limit could possibly grow.  The codes used are those used by IHO with underscores replacing periods.

I appreciate the consequences for SeaDataNet.  It's not just the tools that will need changing. Some partners will also have metadata or data files with C16 embedded that will need editing.  The TTT obviously needs to carefully consider whether such change is worthwhile and if so its timing, which I think would have to be a part of the next major reversioning.

Cheers, Roy.
________________________________
From: Michele FICHAUT [Michele.Fichaut at ifremer.fr]
Sent: 04 May 2009 09:28
To: Lowry, Roy K; Lowry, Roy K
Cc: seavox at mailman.nerc-liv.ac.uk; Weatherall, Pauline; francisco.hernandez at vliz.be
Subject: Re: [Seavox] Sea Area Thesaurus

Dear Roy,

Concerning SeaDataNet, here are some questions :
 - Is this change (C16 to C19) related to the new IHO policy which delegates to national representatives the naming
   of the local sea areas (still under discussion?)
 - Is the high level of C19 the same than C16 (is C16 included as a whole in C19)?
 - Will a mapping between C16 and C19 be provided?
 - Is a national language support planned (particularly for high resolution areas, Manche and English Channel for example)?
 - Is there a maximum length of the code, and the name?

If we adapt this list for SeaDatanet there are consequences on :
+ Mikado, NEMO, the XML schemas

Best regards

Michèle

Lowry, Roy K a écrit :
Dear All,

Some life at last on planet SeaVoX!

The first stage of the Sea Area thesaurus project is now done with the XML publication of an interlinked set of terms at http://vocab.ndg.nerc.ac.uk/list/C191/current. A formatted version of the terms (but not their linkages) may be found as the C191 list at http://seadatanet.maris2.nl/v_bodc_vocab/welcome.aspx

The next job is to obtain suitable public domain polygon co-ordinates corresponding to the terms and arrange for them to be accessible via WFS.  There are a number of potential data sources, including the 1953 S23 co-ordinates held at BODC, data served from the VLIZ gazetteer.  URLs to WFS-accessible polygons will be included as concept definitions as they become available.  An interesting test of OGC interoperability might be to have these served from multiple sources!

A meeting is planned at BODC around 14-15 May to identify additional sources of high resolution data for the C19 regions in the vicinity of the UK together with a set of finer-grained  sub-regions for UK waters that would be added to the thesaurus.

One issue for SeaDataNet colleagues on the list to consider is whether we should consider replacing C16 by C19.  If so, when and how?

Cheers, Roy.

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Michele FICHAUT - IFREMER/BREST - SISMER - B.P. 70 - 29280 PLOUZANE
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Email: Michele.Fichaut at ifremer.fr<mailto:Michele.Fichaut at ifremer.fr>  WWW : http://www.ifremer.fr/sismer/
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