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<title>Re: [GRASS-user] 3-D plane workflow</title>
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Thanks very much.<br>
That is just what I had in mind. Is it then possible to convert that to a raster elevation to use for some height calculations?<br>
<br>
--Adam<br>
<br>
<br>
-----Original Message-----<br>
<b>From: </b>Anna Kratochvílová [<a href="mailto:kratochanna@gmail.com">kratochanna@gmail.com</a>]<br>
<b>Sent: </b>Saturday, March 02, 2013 09:12 AM Pacific Standard Time<br>
<b>To: </b>Adam Dershowitz<br>
<b>Cc: </b>GRASS user list<br>
<b>Subject: </b>Re: [GRASS-user] 3-D plane workflow<br>
<br>
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<p><font size="2">On Wed, Feb 27, 2013 at 12:38 AM, Adam Dershowitz<br>
<adershowitz@exponent.com> wrote:<br>
> I would like to be able to put some surfaces in the space over a DEM. In<br>
> other words, I have a DEM, and then I need to calculate some regions that<br>
> are "keep-out zones" in space above. I can calculate where these surfaces<br>
> are fairly easily in Python, for example. So the output of my calculation<br>
> would be some points. In the easiest example, it would just be 4 sets of<br>
> x,y,z that represent the four corners of a plane.<br>
> I would then like to be able to visually show this plane (or multiple<br>
> planes), over the DEM, and show that the DEM does, or doesn't, penetrate<br>
> this surface. If it does penetrate, I would like to be able to calculate<br>
> the penetration height.<br>
><br>
> The kind of thing that I would like to do, would end up looking like the<br>
> examples of Slovakia precipitation that Mitasova has done. Some of those<br>
> examples show a DEM, and then a surface that is being penetrated by the DEM.<br>
> I have been reading some of the examples for 3D visualization (such as here:<br>
> <a href="http://grasswiki.osgeo.org/wiki/Help_with_3D">http://grasswiki.osgeo.org/wiki/Help_with_3D</a>), but figured that a post here,<br>
> but might get me a little more guidance about a general suggested workflow.<br>
><br>
> In those examples, are the isosurfaces does as 3D rasters? If I just want a<br>
> plane in space, and I have the four corner points, is a 3D raster seem like<br>
> the best way to draw it? Are those examples displayed with NVIZ or<br>
> paraview?<br>
><br>
> Is the following a reasonable approach:<br>
><br>
> Calculate the surfaces in some code and export as faces:<br>
><br>
> F 4<br>
> 0 100 10<br>
> 50 50 80<br>
> 0 0 10<br>
> 0 100 10<br>
><br>
> Then, import into Grass with v.in.ascii.<br>
> Next, I would have to convert to a raster: v.to.rast.<br>
> Then, I would have to convert to an elevation: r.to.rast3elev<br>
> Finally, I could export both the surfaces and the ground DEM with<br>
> r3.out.vtk, and visualize with paraview.<br>
><br>
> Is this a reasonable workflow? If I just need a semitransparent surface, is<br>
> it necessary for it to be 3D, or can it be done with 2.5D (all I really need<br>
> is x,y and elevation, like a DEM). For, example, I might be able to just<br>
> skip the raster version and use v.out.vtk? Or maybe I can just use nviz<br>
> to visualize what I need, if I can get it to the right format.<br>
> If I do convert the plane to a raster, I suppose I can then use mapcalc to<br>
> calculate the height difference between the plane and the ground DEM?<br>
><br>
> I am just looking for some general workflow guidance for a good overall<br>
> approach to get going. It seems like there are some things that are not as<br>
> clear about 3D work in GRASS, and I am just trying to get a reasonable<br>
> picture.<br>
> Any thoughts are greatly appreciate.<br>
><br>
> Thanks much,<br>
><br>
<br>
<br>
Hi Adam,<br>
<br>
I am not sure if this is exactly what you want but have a look at the<br>
attached screenshots. This is done in wxNviz. I created a plane (3<br>
points) with<br>
<br>
v.in.ascii -n input=inputFile.txt output=out format=standard separator=" " z=3<br>
<br>
The file containes what you already used (F 4 ...). Then you can<br>
display it in 3D view. However, the transparency of the surface is not<br>
working well together with the vector (note to developers: the same<br>
issue is in old nviz). You can play with using wire style as in the<br>
screenshot. If it is not clear, just ask for more details.<br>
<br>
Regards,<br>
Anna<br>
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