<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Actually, I think changing the contract on getGeometryType to only ever returning the basic (non-3d) type would clean up driver implementation code a bit. Grepping for it in the drivers, you see a lot of</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="margin: 0px;">CPLAssert(wkbFlatten(poGeom->getGeometryType()) == wkbPoint)</div><div id="bloop_customfont" style="margin: 0px;"><br></div><div id="bloop_customfont" style="margin: 0px;">and</div><div id="bloop_customfont" style="margin: 0px;"><br></div><div id="bloop_customfont" style="margin: 0px;"><div id="bloop_customfont" style="margin: 0px;"> || (poLine->getGeometryType() != wkbLineString</div><div id="bloop_customfont" style="margin: 0px;"> && poLine->getGeometryType() != wkbLineString25D) )</div><div><br></div><div>and very few unqualified calls to it.</div><div><br></div><div>P.</div></div> <div id="bloop_sign_1386967786879561984" class="bloop_sign"><div><br></div><span style="font-family:helvetica,arial;font-size:13px"></span>-- <br>Paul Ramsey<br>http://cleverelephant.ca<div>http://postgis.net</div></div> <br><p style="color:#A0A0A8;">On December 13, 2013 at 12:00:34 PM, Paul Ramsey (<a href="mailto://pramsey@cleverelephant.ca">pramsey@cleverelephant.ca</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>
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<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
I’ve pushed up some work to do this</div>
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<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
https://github.com/pramsey/gdal/tree/isowkb</div>
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<div>I had to change *two* method signatures, which I don’t really
like, both exportToWkb and getGeometryType needed a variant
parameter added. The problem is that getGeometryType returns the
full WKB type, with dimensionality encoded, which makes it somewhat
duplicative of getCoordinateDimension. In an ideal world,
getGeometryType would only return the type number, and
dimensionally information would be inferred from
getCoordinateDimension.</div>
<div><br></div>
<div>Then only the exportToWkb signature would need a variant
parameter.</div>
<div><br></div>
<div>importFromWkb also was changed to ingest the ISO variant if
that’s what it’s fed. No changes to signature required there.</div>
<div><br></div>
<div>P.</div>
<div><br></div>
-- <br>
Paul Ramsey<br>
http://cleverelephant.ca
<div>http://postgis.net</div>
</div>
<br>
<p style="color:#A0A0A8;">On December 12, 2013 at 2:58:05 PM, Even
Rouault (<a href="mailto://even.rouault@mines-paris.org">even.rouault@mines-paris.org</a>)
wrote:</p>
<blockquote type="cite" class="clean_bq">
<div>
<div><span>Le jeudi 12 décembre 2013 23:39:25, Paul Ramsey a écrit
:<br>
> I’ve been looking over the code, and I think I can make
importFromWkb<br>
> consume ISO inputs with relatively minor changes. (during the
geometry<br>
> type determination in the concrete types, it looks easy enough
to add a<br>
> little logic to deal with ISO type numbers) For exportToWkb,
I’m wondering<br>
> if maybe an optional parameter (wkbVariant?) that defaults
to<br>
> wkbVariantOGC would be sufficient?<br>
<br>
Sounds good to me. Is "wkbVariantOGC" the variant currently
implemented ? Is<br>
our 3D support really compliant with an OGC standard ?<br>
<br>
><br>
> It also seems the wkb reader/writer have little handling for
empty geometry<br>
> types. I’d like to add some in, if that’s OK.<br>
<br>
Are you sure about that ?<br>
<br>
See :<br>
<br>
>>> from osgeo import ogr<br>
>>>
ogr.CreateGeometryFromWkb(g.ExportToWkb()).ExportToWkt()<br>
'LINESTRING EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('LINESTRING<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'LINESTRING EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('LINESTRING<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'LINESTRING EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('POLYGON<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'POLYGON EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('MULTILINESTRING<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'MULTILINESTRING EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('MULTIPOLYGON<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'MULTIPOLYGON EMPTY'<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('GEOMETRYCOLLECTION<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'GEOMETRYCOLLECTION EMPTY'<br>
<br>
The only exception is POINT EMPTY due to the lack of wkb
representation for it<br>
:<br>
>>>
ogr.CreateGeometryFromWkb(ogr.CreateGeometryFromWkt('POINT<br>
EMPTY').ExportToWkb()).ExportToWkt()<br>
'POINT (0 0)'<br>
<br>
<br>
><br>
> Fortunately the only substantial difference for ISO WKB is the
type number.<br>
><br>
> I’m starting an isowkb branch on my git repo to hold this
piece of work, I<br>
> don’t think it’ll be very big.<br>
><br>
> Then I’ll start asking about ‘m’ dimensions :)<br>
<br>
That's a fresh new land to explore...<br>
<br>
><br>
> P.<br>
><br>
> --<br>
> Paul Ramsey<br>
> http://cleverelephant.ca<br>
> http://postgis.net<br>
><br>
> On December 12, 2013 at 2:33:41 PM, Even Rouault<br>
> (even.rouault@mines-paris.org) wrote:<br>
><br>
> Le jeudi 12 décembre 2013 21:36:42, Paul Ramsey a écrit
:<br>
> > Hey all,<br>
> > Is there already a facility for writing out ISO-standard
WKB in GDAL? The<br>
> > biggest difference is the wkbGeometryType number for the
case of 3d<br>
> > features. OGR currently uses the old extended SFSQL
adopted by PostGIS.<br>
> > ISO (naturally) did their own thing. As far as I can see,
there’s no<br>
> > support there now, or is there? P.<br>
><br>
> Hi Paul,<br>
><br>
> no, there's no support for ISO WKB yet. We still stick
to<br>
> http://home.gdal.org/projects/opengis/twohalfdsf.html<br>
><br>
> I can imagine we could have exportToISOWkb() method in
OGRGeometry*. Or we<br>
> could add an extra boolean argument bISOWkb to the existing
exportToWkb().<br>
> Not sure about WkbSize() : does the size of ISO WKB blobs
differ from the<br>
> unofficial WKB ?<br>
><br>
> Even<br>
><br>
> --<br>
> Geospatial professional services<br>
> http://even.rouault.free.fr/services.html<br>
<br>
--<br>
Geospatial professional services<br>
http://even.rouault.free.fr/services.html<br></span></div>
</div>
</blockquote>
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