Hi Ben, <br><br><div class="gmail_quote"><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
The problem is that the roots of GIS are in digital cartography,<br>
which is a 2D discipline. So the GIS datamodels were all originally<br>
designed for 2D, including the vector model. Raster elevation<br>
layers served the purpose as simple pseudo-3D models ("2.5 D").<br>
<br></blockquote><div>As far as I can tell in the 2.0 branch we will have support for 3D geometries according to the GML ISO specification. We will be capable of defining solids, etc. <br><br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
As time went by, more and more people from "3D fields", such as<br>
geology created a demand for real 3D data management, so capabilities<br>
to load, view, and (to a limited degree) add 3D data was introduced.<br>
And some GIS (such as GRASS GIS) also learned a limited amount of<br>
3D analysis.<br>
<br>
But many fundamental GIS aspects, such as topology, remain firmly<br>
in the 2D domain, and it will be a long time before that changes,<br>
because 3D topological relationships are a whole lot more complex<br>
than 2D ones. Currently, 3D remains an "add-on" to GIS, that works<br>
more or less well (and then there is 4D, but let's not even get<br>
into that).<br>
<br></blockquote><div> </div><div>I'm agree, and in my opinion, the vast majority of 3D users mainly to give a different perspective of the data for a visual analysis. This is changing, and in the near future 3D geoprocesses (like multiresolution algorithms for massive data) will be absolutelly necessary. <br>
</div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Polygons versus more complex 3D shapes are a good example. By<br>
definition a polygon is a planar construct. Anything more complex than<br>
that must be sub-divided into simpler polygons (usually 3D triangles),<br>
so the GIS vector model can handle them. E.g. a TIN is just a collection<br>
of simple triangles. And any other shape can also be decomposed into<br>
triangular "faces".<br></blockquote><div><br>For the records, gvSIG3D don't support TIN at the moment. <br><br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
-- And I don't think the gvSIG 3D extension handles voxels yet (?)<br></blockquote><div><br>Are you kidding me? ;).<br><br>Cheers!<br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div><div class="h5"><br>
----- Original Message -----<br>
> Yes, you are right.<br>
><br>
> What it is about is how to handle "dirty" polygons that is invalid.<br>
> How to find that they are invalid without putting to much effort in<br>
> it.<br>
><br>
> The isValid function is a GEOS-function and only handles x z<br>
> coordinates as far as I know, so a part of extending PostGIS<br>
> capabilities in 3D is<br>
> taking care of validation. Those functions is not in place yet (I<br>
> think, I have if something new has been committed there by the guy<br>
> implementing TIN and Polyhedralsurface)<br>
><br>
> Do you have a good way of validating that the polygon is coplanar in<br>
> gvSIG, I guess you have to handle invalid data too. How do you<br>
> validate the data?<br>
><br>
> Or same question from another angle. How do you define the plane in 3D<br>
> extension?<br>
><br>
> Or what happens if the extension gets the polygon I had as example?<br>
> I will try when I get it up running :-)<br>
><br>
> I am a novice in 3D so sorry for maybe naive questions.<br>
><br>
><br>
> Regards<br>
> Nicklas<br>
><br>
><br>
><br>
><br>
><br>
> On Wed, 2011-01-19 at 16:03 +0100, Jordi Torres wrote:<br>
> > I missed the link... :S<br>
> ><br>
> > [1]<a href="http://postgis.refractions.net/docs/ch04.html" target="_blank">http://postgis.refractions.net/docs/ch04.html</a><br>
> ><br>
> ><br>
> > 2011/1/19 Jordi Torres <<a href="mailto:jtorresfabra@gmail.com">jtorresfabra@gmail.com</a>><br>
> > Hi Nicklas,<br>
> ><br>
> > What I meant is that a polygon is a two-dimensional shape,<br>
> > enclosing an area with its vertices that is in the same<br>
> > plane, coplanar. If you don't define your polygons this way<br>
> > it's impossible to know how to tesellate and render it. I<br>
> > don't know about the specification of polygons in postgis,<br>
> > but maybe<br>
> > it's up to the user to define its vertices correctly. I<br>
> > found this[1] in the postgis doc, see point 4.3.5, maybe it<br>
> > helps.<br>
> ><br>
> > Greetz.<br>
> ><br>
> > [1]<br>
> ><br>
> ><br>
> > 2011/1/19 Nicklas Avén <<a href="mailto:nicklas.aven@jordogskog.no">nicklas.aven@jordogskog.no</a>><br>
> > sorry about off list posting<br>
> ><br>
> ><br>
> ><br>
> ><br>
> > On Wed, 2011-01-19 at 14:35 +0100, Jordi Torres<br>
> > wrote:<br>
> > > Hi Nicklas,<br>
> > ><br>
> > > Please, let' s take this conversation "on-list".<br>
> > > The<br>
> > attacments did<br>
> > > not pass the list control, that's the reason why I<br>
> > wrote to you<br>
> > > directly. About generating 3D datasets it's simple<br>
> > > if you have<br>
> > the data in .shp<br>
> > > (using shp2pgsql). That's the way I get my data.<br>
> > > In the other hand, a polygon cannot be in more<br>
> > > than<br>
> > one plane in 3D,<br>
> > > if this is the case, this structure must be<br>
> > tessellated into triangles<br>
> > > or at least polygons in the same plane.<br>
> ><br>
> ><br>
> > Well, what do you mean by cannot be in more than one<br>
> > plan?<br>
> ><br>
> > I understand that it cot can when it comes to<br>
> > rendering and so on.<br>
> > And it cannot when it comes to valid polygons.<br>
> ><br>
> > But you can express a polygon in wkt that has<br>
> > vertexpoints in more than<br>
> > one plan.<br>
> ><br>
> > for example:<br>
> > POLYGON((0 0 0,0 5 0, 0 5 5, 10 5 5, 10 5 0, 10 0 0,<br>
> > 0 0 0))<br>
> ><br>
> > In many examples the result is undefined and<br>
> > impossible to decide<br>
> > without more information and that's why I have to<br>
> > deal with it in<br>
> > distance calculations and send an error msg instead<br>
> > of trying to<br>
> > calculate the distance.<br>
> ><br>
> > Or am I missing something?<br>
> ><br>
> > Regards<br>
> > Nicklas<br>
> ><br>
> ><br>
> ><br>
> ><br>
> ><br>
> > > (the same as openGL do when rendering concave<br>
> > polygons). May be the<br>
> > > tesselator included in the 3D extension eats this<br>
> > kind of structure,<br>
> > > but I don't trust.<br>
> > ><br>
> > > About PostGis I am a noob or less than a noob. I<br>
> > only know the basics<br>
> > > to set a database and do a sql query. And I<br>
> > > learned<br>
> > it yesterday :). I<br>
> > > am a 3D developer, and postgis is a tangential<br>
> > theme for me. So for<br>
> > > the questions about postGIS ask to the gurus in<br>
> > > the<br>
> > list... ;)<br>
> > ><br>
> > > Cheers.<br>
> > ><br>
> > ><br>
> > > 2011/1/19 Nicklas Avén<br>
> > > <<a href="mailto:nicklas.aven@jordogskog.no">nicklas.aven@jordogskog.no</a>><br>
> > > Yes, that would be nice :-)<br>
> > ><br>
> > > It is a little bit difficult to create 3D<br>
> > datasets I think, at<br>
> > > least if<br>
> > > the polygons contains more than 3 points<br>
> > (counting the first<br>
> > > and last as<br>
> > > 1) because they have to be in the same<br>
> > > plan.<br>
> > That is the part<br>
> > > in the 3D<br>
> > > distance code that I am most worried<br>
> > > about.<br>
> > Now there is no<br>
> > > real test if<br>
> > > people sends polygons not on one single<br>
> > > plan<br>
> > to the function,<br>
> > > because such a test is quite expensive to<br>
> > > calculate<br>
> > if the polygon has<br>
> > > many points. Also there have to be some<br>
> > tolerance.<br>
> > ><br>
> > > Have you tried the PostGIS trunk lately?<br>
> > ><br>
> > > It will be interesting to test and<br>
> > > visualize st_3d_shortestline through<br>
> > > gvSIG.<br>
> > ><br>
> > > Cheers<br>
> > > Nicklas<br>
> > ><br>
> > ><br>
> > > On Wed, 2011-01-19 at 13:55 +0100, Jordi<br>
> > Torres wrote:<br>
> > > > Hi Nick,<br>
> > > ><br>
> > > > Is a lot of triangular separate<br>
> > > > polygons,<br>
> > if you want the<br>
> > > archive to<br>
> > > > do testing I can send it to you.<br>
> > > ><br>
> > > > Cheers.<br>
> > > ><br>
> > > > 2011/1/19 Nicklas Avén<br>
> > <<a href="mailto:nicklas.aven@jordogskog.no">nicklas.aven@jordogskog.no</a>><br>
> > > > Thanks a lot<br>
> > > ><br>
> > > > I will try it as soon as<br>
> > > > possible.<br>
> > When I have this<br>
> > > woking<br>
> > > > there will be<br>
> > > > a blog post about this extension<br>
> > and comming 3d<br>
> > > distance<br>
> > > > functions in<br>
> > > > postgis.<br>
> > > ><br>
> > > > Is TIN supported? or is it a lot<br>
> > of triangular<br>
> > > separate<br>
> > > > polygons in the<br>
> > > > example picture?<br>
> > > ><br>
> > > > Great work!<br>
> > > > Thanks<br>
> > > ><br>
> > > > /Nicklas<br>
> > > ><br>
> > > ><br>
> > > ><br>
> > > > On Wed, 2011-01-19 at 13:47<br>
> > > > +0100,<br>
> > Jordi Torres<br>
> > > wrote:<br>
> > > > ><br>
> > > > ><br>
> > > > > ---------- Forwarded message<br>
> > ----------<br>
> > > > > From: Jordi Torres<br>
> > <<a href="mailto:jtorresfabra@gmail.com">jtorresfabra@gmail.com</a>><br>
> > > > > Date: 2011/1/19<br>
> > > > > Subject: Re: [Gvsig_english]<br>
> > PostGis + 3D<br>
> > > extension<br>
> > > > > To: Users and Developers<br>
> > > > > mailing<br>
> > list<br>
> > > > ><br>
> > <<a href="mailto:gvsig_internacional@listserv.gva.es">gvsig_internacional@listserv.gva.es</a>><br>
> > > > ><br>
> > > > ><br>
> > > > > Hi Nicklas,<br>
> > > > ><br>
> > > > > Here you have attached a zip<br>
> > file. Substitute the<br>
> > > jars in<br>
> > > > the way Fran<br>
> > > > > told to you.<br>
> > > > ><br>
> > > > > And congrats to jaspa teams!!<br>
> > Good work!<br>
> > > > ><br>
> > > > > Cheers.<br>
> > > > ><br>
> > > > > 2011/1/19 Francisco José<br>
> > Peñarrubia<br>
> > > <<a href="mailto:fpenarru@gmail.com">fpenarru@gmail.com</a>><br>
> > > > ><br>
> > > > ><br>
> > > > > Hi.<br>
> > > > ><br>
> > > > > I just want to remark<br>
> > and say thanks to<br>
> > > JASPA team,<br>
> > > > who did<br>
> > > > > the hard work of this<br>
> > patch in gvSIG<br>
> > > Sprint. I hope<br>
> > > > we can use<br>
> > > > > it in 1.11 release.<br>
> > > > ><br>
> > > > ><br>
> > <a href="http://jaspa.forge.osor.eu/" target="_blank">http://jaspa.forge.osor.eu/</a><br>
> > > > ><br>
> > > > > Best regards.<br>
> > > > ><br>
> > > > > Jordi, please, can you<br>
> > send the latest<br>
> > > jars to<br>
> > > > Niklas?. I will<br>
> > > > > create a patch and<br>
> > upload it to the<br>
> > > repository.<br>
> > > > ><br>
> > > > > El 19/01/2011 13:30,<br>
> > Jordi Torres<br>
> > > escribió:<br>
> > > > > ><br>
> > > > > > Hi Nick and Fran,<br>
> > > > > ><br>
> > > > > > I have started a new<br>
> > thread in the list,<br>
> > > this way<br>
> > > > we won't<br>
> > > > > > merge topics.<br>
> > > > > ><br>
> > > > > > Fran has fixed the<br>
> > issues and now we are<br>
> > > able to<br>
> > > > see 3D<br>
> > > > > > geometries using<br>
> > postigs (attached is a<br>
> > > screenshot<br>
> > > > of a 3D<br>
> > > > > > polygons layer). By<br>
> > the way, polyhedral<br>
> > > is not<br>
> > > > supported by<br>
> > > > > > gvSIG postGis driver<br>
> > (even I don't now<br>
> > > if it is<br>
> > > > OGC<br>
> > > > > > compliant), so you<br>
> > have to decompose it<br>
> > > in<br>
> > > > polygons.<br>
> > > > > ><br>
> > > > > > Cheers!<br>
> > > > > ><br>
> > > > > > -- Jordi Torres<br>
> > > > > > Fabra<br>
> > > > > ><br>
> > > > > > gvSIG 3D blog<br>
> > > > > ><br>
> > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a><br>
> > > > > > Instituto de<br>
> > Automática e Informática<br>
> > > Industrial<br>
> > > > > > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> > > > > ><br>
> > > > > ><br>
> > > > > ><br>
> > ><br>
> > _______________________________________________<br>
> > > > > > Gvsig_internacional<br>
> > mailing list<br>
> > > > > ><br>
> > <a href="mailto:Gvsig_internacional@listserv.gva.es">Gvsig_internacional@listserv.gva.es</a><br>
> > > > > ><br>
> > > ><br>
> > ><br>
> > <a href="http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional" target="_blank">http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional</a><br>
> > > > ><br>
> > > > > -- Fran Peñarrubia<br>
> > > > > Scolab <a href="http://www.scolab.es" target="_blank">www.scolab.es</a><br>
> > > > ><br>
> > > > > Asociación gvSIG<br>
> > > > > <a href="http://www.gvsig.com" target="_blank">www.gvsig.com</a><br>
> > > > ><br>
> > > > ><br>
> > ><br>
> > _______________________________________________<br>
> > > > > Gvsig_internacional<br>
> > mailing list<br>
> > > > ><br>
> > <a href="mailto:Gvsig_internacional@listserv.gva.es">Gvsig_internacional@listserv.gva.es</a><br>
> > > > ><br>
> > > ><br>
> > ><br>
> > <a href="http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional" target="_blank">http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional</a><br>
> > > > ><br>
> > > > ><br>
> > > > ><br>
> > > > ><br>
> > > > ><br>
> > > > > -- Jordi Torres Fabra<br>
> > > > ><br>
> > > > > gvSIG 3D blog<br>
> > > > > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a><br>
> > > > > Instituto de Automática e<br>
> > Informática Industrial<br>
> > > > > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> > > > ><br>
> > > > ><br>
> > > > ><br>
> > > > ><br>
> > > > > -- Jordi Torres Fabra<br>
> > > > ><br>
> > > > > gvSIG 3D blog<br>
> > > > > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a><br>
> > > > > Instituto de Automática e<br>
> > Informática Industrial<br>
> > > > > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> > > ><br>
> > > ><br>
> > > ><br>
> > > ><br>
> > > ><br>
> > > ><br>
> > > > -- Jordi Torres Fabra<br>
> > > ><br>
> > > > gvSIG 3D blog<br>
> > > > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a> Instituto de<br>
> > > > Automática e Informática<br>
> > Industrial<br>
> > > > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > > -- Jordi Torres Fabra<br>
> > ><br>
> > > gvSIG 3D blog<br>
> > > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a> Instituto de<br>
> > > Automática e Informática Industrial<br>
> > > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> ><br>
> ><br>
> ><br>
> ><br>
> ><br>
> ><br>
> ><br>
> > --<br>
> ><br>
> > Jordi Torres Fabra<br>
> ><br>
> > gvSIG 3D blog<br>
> > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a> Instituto de Automática e<br>
> > Informática Industrial<br>
> > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> ><br>
> ><br>
> ><br>
> ><br>
> > -- Jordi Torres Fabra<br>
> ><br>
> > gvSIG 3D blog<br>
> > <a href="http://gvsig3d.blogspot.com" target="_blank">http://gvsig3d.blogspot.com</a> Instituto de Automática e Informática<br>
> > Industrial<br>
> > <a href="http://www.ai2.upv.es" target="_blank">http://www.ai2.upv.es</a><br>
> > _______________________________________________ Gvsig_internacional<br>
> > mailing list<br>
> > <a href="mailto:Gvsig_internacional@listserv.gva.es">Gvsig_internacional@listserv.gva.es</a><br>
> > <a href="http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional" target="_blank">http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional</a><br>
><br>
><br>
> _______________________________________________ Gvsig_internacional<br>
> mailing list<br>
> <a href="mailto:Gvsig_internacional@listserv.gva.es">Gvsig_internacional@listserv.gva.es</a><br>
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<div><div class="h5"><br>
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</div></div></blockquote><br></div><br><br clear="all"><br>-- <br>Jordi Torres Fabra<br><br>gvSIG 3D blog<br><a href="http://gvsig3d.blogspot.com">http://gvsig3d.blogspot.com</a><br>Instituto de Automática e Informática Industrial <br>
<a href="http://www.ai2.upv.es">http://www.ai2.upv.es</a><br>