[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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listserv.gva.es/pipermail/gvsig_internacional/attachments/20110119/c24dfc69/attachment.htm 


More information about the Gvsig_internacional mailing list