[GRASSLIST:78] Re: nviz bird's eye view/shaded relief image

[Paul Kelly]

Hello
For a long time also I have struggled with the limitations of accurate
positioning in NVIZ and have had much more success using the older SG3d
(which only runs on Silicon Graphics workstations at present although it
might be possible to port it to other Unix using the software at
http://www.thp.uni-duisburg.de/Ygl/ ). I am not sure but I think the
'interactive arrow' positioning may be inherent to the 'togl' Tcl/TK to
OpenGL interface that is used in NVIZ. I have found it impossible to use
for very precise positioning.

Would it be helpful to have six positioning sliders for easting, northing
and elevation (i.e. position) and yaw, pitch and roll Euler angles (i.e.
attitude / viewing direction) of the camera / observer? I think this would
be a good idea and may be able to be added to NVIZ---it would be good if
there was some sort of wishlist consensus about this.

You may be able to obtain the same effect by manually editing a 3dview file
in the GRASS database and loading it from the option on the file menu in NVIZ.
This sort of works in the CVS version but I'm not sure if it's there in
5.0.2. There is no command-line option to load a 3dview file at present
like there is in SG3d but I'm fairly sure it would be trivial to add it.

Paul Kelly


On Sun, 18 May 2003, Nick Cahill wrote:

> A better way to make a shaded relief map might be to use r.out.tif,
> which will write a tif file of your map. You might be able to adjust
> the tones, to lighten the shadows, by modifying the color table of the
> shaded relief map using r.colors.
>
> I would be interested too in setting the view in NVIZ without using the
> interactive arrow, though.
>
> Nick Cahill
>
> On Sunday, May 18, 2003, at 05:38  AM, Ian Macmillan wrote:
>
> > Hi all, I am trying to use NVIZ and am having a hard time getting a
> > nice bird's
> > eye view.  The "top" button centers the image nicely, however north
> > generally
> > points left diagonally (or some other random direction).  Is there
> > anyway to
> > set the view for nviz other than that interactive arrow (ie command
> > line)?
> >
> > I am ultimately trying to make a nice shaded relief map, without any
> > perspective.  I used shade.rel.sh, however obtaining nice lighting is
> > non-trivial with this script (things are usually too dark, regardless
> > of sun
> > angle).  Any ideas out there?  I am using GRASS 5.0.0 on OSx 10.2.6
> >
> > Thanks,
> > Ian
> >
>
>