[Gvsig_english] Fwd: PostGis + 3D extension

Nicklas Avén nicklas.aven at jordogskog.no
Wed Jan 19 14:48:56 CET 2011


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




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