Helena,
The data included in the slovakia3d set works fine,
the 3d region is in this case preset to 0.0-4000.0.
However, if I change the 3d settings, I run into
the same problem:
g.region b=3000.0
r3.mapcalc test=1.0
loading the new volume "test" into nviz places it at the
wrong z-location (0.0 - 1000.0 instead of 3000.0 - 4000.0).
Slices visualisation gives me the expected result, although
at the wrong location.
If I reset the region's z-range to 0.0 - 4000.0,
nviz shows "test" extents to be 0.0 - 4000.0.
If I slice through the data, however it appears at
the RIGHT position (3000.0 - 4000.0). The rest of
the z-range is displayed as NULL (btw., it would be
nice to have transparent NULL voxels).
I hope this will help to track down the problem.
Best wishes,
Benjamin
----- Originalnachricht -----
Von: Helena Mitasova <hmitaso@unity.ncsu.edu>
Datum: Samstag, 11. März 2006 2:56 pm
Betreff: Re: [GRASS5] Voxel progress
>
> HOWEVER, I fail to visualise such a layer model in NVIZ.
> The first problem is that NVIZ seems to be unable to correctly
> position volumes that have a bottom > 0.0.Ben,
have you tried whether the current nviz volumes work with the
Slovakia data set?
http://mpa.itc.it/grasstutor/data_menu2nd.phtmlWhen the volume support was written the 3D region definition was
separate from the
2D region - later they were merged and it is possible that the nvizvolume support has not been
adjusted properly. Also, this capability has not been tested much
so
there could be bugs.
So let me know whether you see the same problems with the Slovakia
data set and we
can try to track it down.Helena
>
> You can test this even with a very primitive volume
> (use the 3d region settings as shown above):
>
> r3.mapcalc test=1.0
>
> If you load this into NVIZ (and set the bottom of the 3d region >> 0.0),
> it will not display the extents of the volume as it should.
> If you start rotating the view around a bit and increase
> height enough, the extents will be temporarily visible and you
will
> see
> that the whole model has been
> displaced from its original z-range 9.0 to 12.0 and is displayed
> at 0.0 to 3.0!
>
> Obviously, it is not possible to display slices or isosurfaces in> such a
> model, as the NVIZ extent and the real data extent do not match.
> So this seems to be a bug in NVIZ(?).
>
> But here is what really puzzles me: if I adjust 3d region
settings and
> set the bottom to 0.0, NVIZ shows the correct extent, but has the
same> problems!
> I.e. I only get a display of the extent as wireframe for as long as
> rotate the view, change the height or whatever.
>
> Everything disappears after that and I cannot display slices or
> isosurfaces.
>
> is it possible that NVIZ has trouble with small 3d regions or
high 3d
> resolution?
> Am I doing something totally silly?
>
> Finally, some points that I could not figure out from any
> documentation
> and am still a bit unsure about. Maybe someone could reaffirm my
> conclusions about these:
>
> 1. GRASS Z coordinates increase towards the top of the region
> 2. r3.in.ascii expects the bottom slice first in the ASCII input
file>
> I would so much like to get this working. It would be tremendously
> useful for archaeological applications of GRASS GIS!
>
> Best,
>
> Benjamin
>
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