[postgis-devel] EWKB proposal for OGC

Martin Daly Martin.Daly at cadcorp.com
Fri Dec 31 09:43:30 PST 2004


Paul,
 
I like the 'M' part, including POINTM, LINESTRINGM, etc, but I'm uncomfortable with the SRID parts.  EPSG numbers are only sort-of anointed within OGC.  There are also many specs where the SRID is not a number at all, but is a string/anyURI/URN/whatever.  Also, there is already WKT for CRS-s because the EPSG database is not (and does not claim to be) comprehensive.  My gut feeling is that this part would not be well received.
 
I have an idea of the members (particulary voting ones) that would be interested in this change proposal.  You and I could canvass their opinion in NY, and make a decision later.  Does that sound OK?
 
A Happy New Year to all,
Martin

	-----Original Message----- 
	From: Paul Ramsey [mailto:pramsey at refractions.net] 
	Sent: Thu 30/12/2004 18:35 
	To: PostGIS Development Discussion; Martin Daly 
	Cc: 
	Subject: Re: [postgis-devel] EWKB proposal for OGC
	
	

	Martin,
	What do you think of the proposal as it stands? If we write and format
	it up do you think we could put it before the April meeting?
	Paul
	
	strk at refractions.net wrote:
	
	> On Tue, Dec 28, 2004 at 01:45:09AM +0900, Paul Selormey wrote:
	>
	>>Unfortunately, the 99-402r2 is not yet available to some of us
	>>the non-OGC members, and therefore commenting on these extensions
	>>may not be right.
	>
	>
	> Martin Daly sent that document as an attachent on this list:
	> http://postgis.refractions.net/pipermail/postgis-devel/2004-December/000695.html
	>
	>
	>>I have just these:
	>>1. You have used "misure" in the documents, do you mean "measure"?
	>
	>
	> Yes, corrected.
	>
	>
	>>2. I wish the presence of the SRID in the geometry WKT is a suffix, since
	>>   it can be considered optional and should not break existing codes:
	>>   "POINT(1 2);SRID=4326"
	>
	>
	> It *is* optional (meaning undefined SRID, -1 for postgis).
	> Would existing code work with POINTM(1 2 3) or POINT(1 2 3 4) ?
	> Also, EWKB will also probably break existing code, any existing
	> case of compatibility ?
	>
	>
	>>BTW, any plan to define WTK for triangle, rectangle, circle and other
	>>geometries defined in GML 3.x?
	>
	>
	> Not that I'm aware of.
	> --strk;
	>
	>
	>>Best regards,
	>>Paul.
	>>
	>>----- Original Message -----
	>>From: <strk at refractions.net>
	>>To: "PostGIS Development Discussion" <postgis-devel at postgis.refractions.net>
	>>Cc: "Paul Ramsey" <pramsey at refractions.net>
	>>Sent: Monday, December 27, 2004 9:01 PM
	>>Subject: [postgis-devel] EWKB proposal for OGC
	>>
	>>
	>>
	>>>As suggested by Martin Daly I've made a draft proposal for ZM and
	>>>SRID inclusion in WKB and WKT.
	>>>
	>>>Differently to the Z-Geometry proposal I did not specify semantic
	>>>of the M values, as I don't see any "standardizable" behaviour
	>>>for them. For example, M(isures) could represent temperature
	>>>(linear interpolation meaningful) as well as time (meaningless
	>>>linear interpolation).
	>>>
	>>>Draft attached, comments expected.
	>>>
	>>>--strk;
	>>>
	>>
	>>
	>>--------------------------------------------------------------------------------
	>>
	>>
	>>
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	>>>postgis-devel at postgis.refractions.net
	>>>http://postgis.refractions.net/mailman/listinfo/postgis-devel
	>>>
	>>
	>>
	>>_______________________________________________
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	>
	>
	
	

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