[GRASS-user] 3-D plane workflow

[Adam Dershowitz]

On 2/26/13 9:56 PM, "Hamish" <hamish_b at yahoo.com> wrote:

>Adam wrote:
>> I would like to be able to put some surfaces in the space over
>> a DEM.
>
>in NVIZ, add a new raster surface, and set the map to a constant
>value instead of a map name. You can either change the value of
>the constant or the z-position offset to move it around.

That won't do what I need.  The problem is that the planes I want are
finite and not horizontal.  Instead they are polygons where I have the
corner points defined.  For example, just picture an arbitrarily oriented
square floating in space over the DEM based ground.


>
>For a finite surface area, use r.plane or like
>  r.mapcalc "constmap = 100"
>and load a second raster surface in NVIZ's raster controls.

I suppose I could calculate out the dip and azimuth for r.plane, or the
equivalent equations for r.mapcalc.  Then, I would need to  generate a
mask as well.  
Another thought that I had was to import the points as vectors, then to
use r.surf.nnbathy to generate the raster surface values.


>You can also set its transparency level to make it translucent
>for a nice see-through effect.
>
>3D vector faces may work as well, but they are not as mature.
>
>
>Hamish
>
>ps- Helena/Carla: re. the shading I think there is some bug in
>at least tcl/tk NVIZ where one of the light sources (the direct
>one?) gets turned off and does not go back on. the only way back
>is to save the state and restart NVIZ.


Thanks for the info.  It is helpful.

--Adam