[GRASS-user] Filling 2D polygons NVIZ?

GRASS GRASS user
1

Hi,

I was wondering if there are any plans to enable filling of 2D polygons in
NVIZ.

I'm using GRASS 7 but it appears that this feature currently isn't
available.

My workaround is summarised below, but perhaps someone could suggest a
simpler approach. Overlaying a rasterised vector derived simply from
v.to.rast does not give a good display in NVIZ given the topography of the
base DEM layer, hence the method below which extracts DN values from the
DEM.

Summary:
convert 2D polygon to raster (v.to.rast)
create mask from latter raster
add mask (r.mask) and create new layer using r.mapcalc extracting cell
values from DEM: if( dem,dem,0 )
set colour of new raster using r.colors
in NVIZ set Z position of new layer above DEM (e.g., 100)

Cheers,
Richard
GRASS 7
Version: 57592

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2

On Sun, Sep 8, 2013 at 10:08 AM, RichardC <richtcooper@hotmail.com> wrote:

Hi,

I was wondering if there are any plans to enable filling of 2D polygons in
NVIZ.

I'm using GRASS 7 but it appears that this feature currently isn't
available.

AFAIK it only works with 3D polygons.
Untested: convert your 2D polygons to 3D with z=0?

Markus

3

I tend to find that after running v.to.3d the resulting polygons are
distorted from the original.

E.g.,

v.to.3d --overwrite input=w001001urban2_rtv_split@PERMANENT
output=w001001urban2_rtv_split_3d height=0

Attached images show the results. I've also tried using v.split to see if
that helps, but there is no difference.

<http://osgeo-org.1560.x6.nabble.com/file/n5077179/2dview.jpg&gt;

<http://osgeo-org.1560.x6.nabble.com/file/n5077179/3dview.jpg&gt;

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4

I've added a ticket at: http://trac.osgeo.org/grass/ticket/2076

Here's shot of the layer in gvSIG's 3D viewer, so I think may be related to
how NVIZ displays 3D polygons...

<http://osgeo-org.1560.x6.nabble.com/file/n5077486/gvsig.jpg&gt;

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