POV-Ray : Newsgroups : povray.binaries.tutorials : Re: Where are my lights???? : Re: Where are my lights???? Server Time
1 Jun 2023 00:52:10 EDT (-0400)
  Re: Where are my lights????  
From: Ken
Date: 9 Apr 1999 01:37:44
Message: <370D82E5.175D0F9A@pacbell.net>

  I took a look at your scene file and think I can explain your
proceedural misunderstanding. I would have tried rendering it
after making some changes but I am rendering a scene while on line
and don't want to stop it right now.
  You have each of your disks located at y = 0. You also have a
couple of cylinders at y = 0 that are at least 1/2 a pov unit thick
(I didn't memorize all of the paramaters of your scene so bear with
me on my generalizations}. Now you have added several cylinder light
sources ringing this construction all at a uniform distance of 80 units
or so and each is lying on the y = 0 zero plane. All I can tell you is
that in pov, as it is in real life, light cannot travel through solid
objects and that is what you are expecting them to do with the current
arrangement. Add a positive y value to your light statements and they
should start to work. I am almost certain that is your problem.

They are specified now as:

 light_source { <0, 0, 80 > stuff }

Try changing them to:

 light_source { <0, 3, 80 > stuff }

and see if that makes a difference in their perfomance.

Also when I checked to see what camera position you are using
I noticed that you have your camera at:

camera { location < 0, 200, 0 > look_at <0,0,0>}

You are very lucky that this alone is not crashing the program. In
most cases it causes a divide by zero error and the program terminates
with a program fualt. Even if you are getting away with it now it is not
a good practice to continue. If you need a straight overhead position
like this always add a very small amount of -z to the camera location.

camera { location < 0, 200, -0.0001 > look_at <0,0,0>}

That very tiny amount will keep the program from having the divide by
zero problem and will in all but the most extreme cases be totaly
undetectable in the way the scene looks when rendered.

Ken Tyler


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