grass4.1/3d.view.sh

[John Mackenzie]

Thiru,

3d.view.sh is just a canned set of views.  Look at the commands 
in the script to see how it's done.

We've used d.3d here for stacking images showing
groundwater pollutant concentrations at various
depths in an aquifer.  Resize the display monitor
window so it's tall, then 
   d.frame -e
Divide the monitor window into as many frames
as you want, e.g.
   d.frame -c frame=one at=75,100,0,100
   d.frame -c frame=two at=50,75,0,100
   d.frame -c frame=three at=25,50,0,100
   d.frame -c frame=four at=0,25,0,100
then 
   d.frame -s one
   d.3d map=map.one elevation=elev.map exaggeration= lines= color=
   d.frame -s two
   d.3d map=map.two elevation=elev.map exaggeration= lines= color=
   etc.
You just have to experiment.  Setting exaggeration=0 gives flat
maps; lines= determines how many pixels between trending lines (a
function of current resolution); I like a trending line color=gray.

If you want to control viewing angle, center of view, eye position, 
etc, it's generally easier to work through the menu.  Experiment
with the view using a coarse grid, lines only.  Then when you get 
what you like, switch to fine resolution will colored cells, which
can take some time to display.

d.3d can't handle vectors directly, but last year I fooled around with
something Malcolm Williamson at CAST and some others suggested:
   d.mon start=CELL
   d.rast map1
   d.vect vec1
   d.vect vec2
   etc.
   d.mon stop=CELL
This creates a composite raster image file with vectors overlaid on
raster(s) which you won't see displayed.  Then 
   d.mon select= your previous viewing monitor
   g.region rast=D_cell
(BTW, the CELL raster file is in its own arbitrary x-y coordinates,
so you may have to define the dimensions of CELL before starting it with
   setenv GRASS_WIDTH w
   setenv GRASS_HEIGHT h
where w and h are numbers of pixels, maybe 2000 x 1500.)
   d.frame -e
   d.3d map=D_cell etc.
I'm probably leaving out a step or two, but if you experiment, you
should be able to get some eye-poppin' stuff.
 
Our dean occasionally drags VIP's through our site who are completely 
clueless about GIS, and if I demo r.mapcalc and their eyes start
to glaze over I can always switch to some razzle-dazzle.  
They like the info-gasm, the rush of thinking they're absorbing 
far more information than they really are.

John Mackenzie
U. of Delaware

> Thank you very much for responding very quickly.
> I am a very beginner to gis.
> I want to produce some 3d picture.
> 
> Could you please tell me how to achieve that?
> 
> Thanks again
> 
> Thiru