POV-Ray
This assignment is not compulsory
Sometimes it is necessary to produce more realistic images,
containing shadow, reflection and refraction. The systems we have
looked at so far, have no (direct) support for such effects. One system
that can produce striking images is POV-Ray
(which uses ray
tracing) and I have installed it on the student system.
To run it you should first copy some init-files. This should be done
once.
cp -r
/chalmers/users/thomas/VIS/povray/.povray .
Note the dot
Then set the path:
If you are using tcsh:
set path = ( $path
/chalmers/users/thomas/VIS/povray/bin )
If you are using bash:
export
PATH=$PATH:/chalmers/users/thomas/VIS/povray/bin
To run POV-Ray you need a description of a scene, that contains
the geometry of objects, light sources etc. There are many scene-files
available. Look in /chalmers/users/thomas/VIS/povray/share/povray-3.6/scenes/
To minimize the amount of typing (or cutting and pasting) I
suggest that you create a soft link to this directory:
ln -s /chalmers/users/thomas/VIS/povray/share/povray-3.6/scenes scenes
ls scenes will show you the directories containing scenes.
Let us start with a scene from the advanced directory, the file scenes/advanced/biscuit.pov. If
we look at the file (it is an ordinary text file) we can understand
some parts of the description. In the beginning of the file there are
the two lines:
// +w320 +h240
// +w800 +h600 +a0.3 +am2
giving suitable parameters to the POV-Ray-program, +w gives the width
(in pixels) and +h the height. Let us start with the first set.
povray +w320 +h240
scenes/advanced/biscuit.pov
If everything works, there should be some printout in the terminal
window and we should get a new window where we can see the scene being
rendered. When the image is complete, the new window disappears, but
the image is stored in biscuit.png
. We can look at the image by typing xv biscuit.png for example. To
make an image of higher quality we increase w and h; the runs requires
some two minutes, but the result is worth waiting for. Note, for
example, the shadows and the refraction in the glass jar.
If you do not want to wait, I have stored the image. Type:
xv
/chalmers/users/thomas/VIS/povray/biscuit.png
Another nice images is: xv
/chalmers/users/thomas/VIS/povray/woodbox.png
Here is a small version of the image:
The learn a lot about POV-Ray, there is a manual page,
/chalmers/users/thomas/VIS/povray/man/man1/povray.1
and a doc-directory:
/chalmers/users/thomas/VIS/povray/share/doc/povray-3.6/
These pages are also
available from the POV-Ray homepage
A web-page, with stunning ray traced images, is the Internet Raytracing Competition.
