Dear GRASS list,
I’m a new GRASS user and I’m trying to create a 3d map using NVIZ from the GRASS command line. The map contains a number of vector layers, as well as a single raster that I’m using for the elevation model. So far I have been able to create a 3d surface from the raster, overlaid with lines from a vector file using the syntax:
nviz elevation=raster_filename vector=vector_filename
For the next step, I’d like to apply symbology to the vector layer. Specifically, I want to fill polygons with a specified color (high priority), set layer-specific transparency (low priority), etc . . … I haven’t been able to figure out how to do that, or even whether it’s possible. I’m considering another way to accomplish this, by simply creating a 2d version of the map with the desired symbology in QGIS, exporting that as a raster, then using that file with the color parameter to nviz. That solution does not seem optimal, however.
Eventually I’m working to use NVIZ to animate changes in the elevation surface as a time-series, but for now I’ll be happy if I can get individual images with the desired look.
I’ll welcome any advice, suggestions, tips, direction to apropos documentation, etc…
Thanks,
Gregory
P.s.
In case it’s relevant, here’s some system/software info;
Mac OS 10.8.3
GRASS 6.4.2 (binary installation from William Kyngesburye)
All required frameworks also installed via Kyngesburye’s binaries
Hi,
consider using GRASS 7 because it includes v.colors, so you can set
different colors according to some attribute value. Nviz functionality
in GRASS 7 is integrated in wxGUI (select 3D view in Map Display). You
can use m.nviz.image for command line. In the nviz version you are
using, there should be 'thematic mapping' option for points (color,
symbol, size). In wxNviz, there is similar option also for line width.
On Mon, Mar 25, 2013 at 5:42 PM, Gregory Penn <gregory.penn@gmail.com> wrote:
For the next step, I'd like to apply symbology to the vector layer.
Specifically, I want to fill polygons with a specified color (high
sorry, it's possible to display only bounderies of 2D polygons (in all
versions), you could either try to display it as a raster or create
and display 3D polygons (by adding z coordinate to areas, but you
probably don't want this).
priority), set layer-specific transparency (low priority), etc . . .. I
transparency is supported only for raster and 3D raster layers
haven't been able to figure out how to do that, or even whether it's
possible. I'm considering another way to accomplish this, by simply creating
a 2d version of the map with the desired symbology in QGIS, exporting that
as a raster, then using that file with the `color` parameter to nviz. That
solution does not seem optimal, however.
Eventually I'm working to use NVIZ to animate changes in the elevation
surface as a time-series, but for now I'll be happy if I can get individual
images with the desired look.
I suggest using m.nviz.image (you can set view, light, ... parameters
interactively in GUI and generate the m.nviz.image command from
toolbar) or you can play with the new animation tool in GRASS 7.
Anna
Anna,
Thank you for your thorough and helpful response. I'll install GRASS 7 as
you advised. I'm looking forward to trying it out.
Cheers,
Gregory
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