[Gvsig_english] Fwd: PostGis + 3D extension
Jordi Torres
jtorresfabra at gmail.com
Wed Jan 19 16:03:56 CET 2011
I missed the link... :S
[1]http://postgis.refractions.net/docs/ch04.html
2011/1/19 Jordi Torres <jtorresfabra at gmail.com>
> Hi Nicklas,
>
> What I meant is that a polygon is a two-dimensional shape, enclosing an
> area with its vertices that is in the same plane, coplanar. If you don't
> define your polygons this way it's impossible to know how to tesellate and
> render it. I don't know about the specification of polygons in postgis, but
> maybe it's up to the user to define its vertices correctly. I found this[1]
> in the postgis doc, see point 4.3.5, maybe it helps.
>
> Greetz.
>
> [1]
> 2011/1/19 Nicklas Avén <nicklas.aven at jordogskog.no>
>
>> sorry about off list posting
>>
>>
>>
>>
>> On Wed, 2011-01-19 at 14:35 +0100, Jordi Torres wrote:
>> > Hi Nicklas,
>> >
>> > Please, let' s take this conversation "on-list". The attacments did
>> > not pass the list control, that's the reason why I wrote to you
>> > directly.
>> > About generating 3D datasets it's simple if you have the data in .shp
>> > (using shp2pgsql). That's the way I get my data.
>> > In the other hand, a polygon cannot be in more than one plane in 3D,
>> > if this is the case, this structure must be tessellated into triangles
>> > or at least polygons in the same plane.
>>
>> Well, what do you mean by cannot be in more than one plan?
>>
>> I understand that it cot can when it comes to rendering and so on.
>> And it cannot when it comes to valid polygons.
>>
>> But you can express a polygon in wkt that has vertexpoints in more than
>> one plan.
>>
>> for example:
>> POLYGON((0 0 0,0 5 0, 0 5 5, 10 5 5, 10 5 0, 10 0 0, 0 0 0))
>>
>> In many examples the result is undefined and impossible to decide
>> without more information and that's why I have to deal with it in
>> distance calculations and send an error msg instead of trying to
>> calculate the distance.
>>
>> Or am I missing something?
>>
>> Regards
>> Nicklas
>>
>>
>>
>>
>> > (the same as openGL do when rendering concave polygons). May be the
>> > tesselator included in the 3D extension eats this kind of structure,
>> > but I don't trust.
>> >
>> > About PostGis I am a noob or less than a noob. I only know the basics
>> > to set a database and do a sql query. And I learned it yesterday :). I
>> > am a 3D developer, and postgis is a tangential theme for me. So for
>> > the questions about postGIS ask to the gurus in the list... ;)
>> >
>> > Cheers.
>> >
>> >
>> > 2011/1/19 Nicklas Avén <nicklas.aven at jordogskog.no>
>> > Yes, that would be nice :-)
>> >
>> > It is a little bit difficult to create 3D datasets I think, at
>> > least if
>> > the polygons contains more than 3 points (counting the first
>> > and last as
>> > 1) because they have to be in the same plan. That is the part
>> > in the 3D
>> > distance code that I am most worried about. Now there is no
>> > real test if
>> > people sends polygons not on one single plan to the function,
>> > because
>> > such a test is quite expensive to calculate if the polygon has
>> > many
>> > points. Also there have to be some tolerance.
>> >
>> > Have you tried the PostGIS trunk lately?
>> >
>> > It will be interesting to test and visualize
>> > st_3d_shortestline through
>> > gvSIG.
>> >
>> > Cheers
>> > Nicklas
>> >
>> >
>> > On Wed, 2011-01-19 at 13:55 +0100, Jordi Torres wrote:
>> > > Hi Nick,
>> > >
>> > > Is a lot of triangular separate polygons, if you want the
>> > archive to
>> > > do testing I can send it to you.
>> > >
>> > > Cheers.
>> > >
>> > > 2011/1/19 Nicklas Avén <nicklas.aven at jordogskog.no>
>> > > Thanks a lot
>> > >
>> > > I will try it as soon as possible. When I have this
>> > woking
>> > > there will be
>> > > a blog post about this extension and comming 3d
>> > distance
>> > > functions in
>> > > postgis.
>> > >
>> > > Is TIN supported? or is it a lot of triangular
>> > separate
>> > > polygons in the
>> > > example picture?
>> > >
>> > > Great work!
>> > > Thanks
>> > >
>> > > /Nicklas
>> > >
>> > >
>> > >
>> > > On Wed, 2011-01-19 at 13:47 +0100, Jordi Torres
>> > wrote:
>> > > >
>> > > >
>> > > > ---------- Forwarded message ----------
>> > > > From: Jordi Torres <jtorresfabra at gmail.com>
>> > > > Date: 2011/1/19
>> > > > Subject: Re: [Gvsig_english] PostGis + 3D
>> > extension
>> > > > To: Users and Developers mailing list
>> > > > <gvsig_internacional at listserv.gva.es>
>> > > >
>> > > >
>> > > > Hi Nicklas,
>> > > >
>> > > > Here you have attached a zip file. Substitute the
>> > jars in
>> > > the way Fran
>> > > > told to you.
>> > > >
>> > > > And congrats to jaspa teams!! Good work!
>> > > >
>> > > > Cheers.
>> > > >
>> > > > 2011/1/19 Francisco José Peñarrubia
>> > <fpenarru at gmail.com>
>> > > >
>> > > >
>> > > > Hi.
>> > > >
>> > > > I just want to remark and say thanks to
>> > JASPA team,
>> > > who did
>> > > > the hard work of this patch in gvSIG
>> > Sprint. I hope
>> > > we can use
>> > > > it in 1.11 release.
>> > > >
>> > > > http://jaspa.forge.osor.eu/
>> > > >
>> > > > Best regards.
>> > > >
>> > > > Jordi, please, can you send the latest
>> > jars to
>> > > Niklas?. I will
>> > > > create a patch and upload it to the
>> > repository.
>> > > >
>> > > > El 19/01/2011 13:30, Jordi Torres
>> > escribió:
>> > > > >
>> > > > > Hi Nick and Fran,
>> > > > >
>> > > > > I have started a new thread in the list,
>> > this way
>> > > we won't
>> > > > > merge topics.
>> > > > >
>> > > > > Fran has fixed the issues and now we are
>> > able to
>> > > see 3D
>> > > > > geometries using postigs (attached is a
>> > screenshot
>> > > of a 3D
>> > > > > polygons layer). By the way, polyhedral
>> > is not
>> > > supported by
>> > > > > gvSIG postGis driver (even I don't now
>> > if it is
>> > > OGC
>> > > > > compliant), so you have to decompose it
>> > in
>> > > polygons.
>> > > > >
>> > > > > Cheers!
>> > > > >
>> > > > > --
>> > > > > Jordi Torres Fabra
>> > > > >
>> > > > > gvSIG 3D blog
>> > > > > http://gvsig3d.blogspot.com
>> > > > > Instituto de Automática e Informática
>> > Industrial
>> > > > > http://www.ai2.upv.es
>> > > > >
>> > > > >
>> > > > >
>> > _______________________________________________
>> > > > > Gvsig_internacional mailing list
>> > > > > Gvsig_internacional at listserv.gva.es
>> > > > >
>> > >
>> >
>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>> > > >
>> > > > --
>> > > > Fran Peñarrubia
>> > > > Scolab
>> > > > www.scolab.es
>> > > >
>> > > > Asociación gvSIG
>> > > > www.gvsig.com
>> > > >
>> > > >
>> > _______________________________________________
>> > > > Gvsig_internacional mailing list
>> > > > Gvsig_internacional at listserv.gva.es
>> > > >
>> > >
>> >
>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>> > > >
>> > > >
>> > > >
>> > > >
>> > > >
>> > > > --
>> > > > Jordi Torres Fabra
>> > > >
>> > > > gvSIG 3D blog
>> > > > http://gvsig3d.blogspot.com
>> > > > Instituto de Automática e Informática Industrial
>> > > > http://www.ai2.upv.es
>> > > >
>> > > >
>> > > >
>> > > >
>> > > > --
>> > > > Jordi Torres Fabra
>> > > >
>> > > > gvSIG 3D blog
>> > > > http://gvsig3d.blogspot.com
>> > > > Instituto de Automática e Informática Industrial
>> > > > http://www.ai2.upv.es
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > --
>> > > Jordi Torres Fabra
>> > >
>> > > gvSIG 3D blog
>> > > http://gvsig3d.blogspot.com
>> > > Instituto de Automática e Informática Industrial
>> > > http://www.ai2.upv.es
>> >
>> >
>> >
>> >
>> >
>> >
>> > --
>> > Jordi Torres Fabra
>> >
>> > gvSIG 3D blog
>> > http://gvsig3d.blogspot.com
>> > Instituto de Automática e Informática Industrial
>> > http://www.ai2.upv.es
>>
>>
>>
>
>
> --
> Jordi Torres Fabra
>
> gvSIG 3D blog
> http://gvsig3d.blogspot.com
> Instituto de Automática e Informática Industrial
> http://www.ai2.upv.es
>
--
Jordi Torres Fabra
gvSIG 3D blog
http://gvsig3d.blogspot.com
Instituto de Automática e Informática Industrial
http://www.ai2.upv.es
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