[GRASSLIST:5031] New volume data set

[Markus Neteler]

Here a fwd from the developers list from Helena Mitasova:

On Thu, Dec 02, 2004 at 12:56:45PM -0500, Helena Mitasova wrote:
> New data set for testing the GRASS5.7 volume support has been added
> to the GRASS Sample datasets (http://grass.itc.it/data.html):
> it includes Slovakia DEM and Precipitation data.
> You can get it directly from here:
> http://mpa.itc.it/grasstutor/data_menu2nd.phtml
> See sample visualization here http://grass.itc.it/grid3d/index.html
> (images on the top of the page)
> The volume visualization still needs some "tuning"
> so below are some hints how to make the images.
>                                                                                             
> Let us know if there are any serious problems
> (but read the below hints before complaining that you don't see
> anything)
>                                                                                             
> Helena
> -----------------------------------------------------------
> Quick tour:
>  The map 'dem500' is used for a DEM.
>  There is a 3D file 'precip3d.500z50' that can be used
>  for isosurfaces and cross-sections.
>                                                                                             
>  nviz el=dem500
>                                                                                             
>  Then load the volume (Panel -> Volume -> New).
>                                                                                             
>  To see the isosurfaces use values between 600 and 1300
>  (e.g. 700 and 1000 with transparency of approx. 100 and
>   a third isosurface 1300 with no transparency).
>                                                                                             
>  Set the polygon resolution to 3 or less (note that for
>  resolution 1 you may need to wait a little depending on your
>  machine's speed) to render the volume.