<br><div class="gmail_quote">On Thu, Aug 4, 2011 at 11:22 PM, Sandro Santilli <span dir="ltr"><<a href="mailto:strk@keybit.net">strk@keybit.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">On Thu, Aug 04, 2011 at 07:46:39AM +0200, Oyvind Idland wrote:<br>
> Oh.. sweet chaos!<br>
><br>
> The lack of a WKB-spec with Z (and M) ordinates seems to have triggered a<br>
> bunch of WKB-flavours, such as<br>
> - OGR's "Two-and-a-half-D extensions for Simple Features"<br>
> - FDO's FGF-format<br>
> - Postgis EWKB<br>
><br>
> I found the EWKB proposal here, but probably not the latest:<br>
> <a href="http://postgis.refractions.net/pipermail/postgis-devel/2004-December/000710.html" target="_blank">http://postgis.refractions.net/pipermail/postgis-devel/2004-December/000710.html</a><br>
><br>
> As far as I can see, it is fairly similar in structure as the SQL/MM, except<br>
> for the optional SRID. The object-type ID's are of course not the same.<br>
><br>
> In addition, SQL/MM specifies CircularString/CurvePolygon/CompundCurve etc<br>
> aswell, would be nice to have these implemented in GEOS aswell (PostGIS has<br>
> done some work here, not sure what)<br>
><br>
> I got two versions of the SQL/MM spec in PDF, the earliest (2nd edtion)<br>
> dates from 2002. I'll send you the newest right away.<br>
><br>
> For now, I'll try to make a simple hack on the existing WkbReader.<br>
><br>
> Would be nice with a more united WKB-world...<br>
<br>
</div>Please use an enum for different WKB types, it's the best we can have.<br>
I confirm any extension support comes from PostGIS EWKB, which is<br>
documented in doc/ZMSgeoms.txt, which is the document submitted as<br>
proposal to the OGC (not sure about the outcome of that).<br>
<br>
--strk;<br>
<br></blockquote></div><br>OGC is currently working on harmonization with ISO, and they will probably adopt SQL-mm part 3 (3D coordinates, WKB, etc):<br><br><a href="http://www.opengeospatial.org/projects/groups/sfswg">http://www.opengeospatial.org/projects/groups/sfswg</a><br>
<br><br>-- Oyvind<br><br><br>