POV-Ray : Newsgroups : povray.general : How to make spotlight not start out as a point? Server Time
31 Oct 2024 23:31:39 EDT (-0400)
  How to make spotlight not start out as a point? (Message 1 to 2 of 2)  
From: jhu
Subject: How to make spotlight not start out as a point?
Date: 23 Jul 2014 16:50:00
Message: <web.53d01fbcc6b3adf5657c65ce0@news.povray.org>
I'd like the start to be of some arbitrary radius instead of a point. How would
I do this?


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From: Alain
Subject: Re: How to make spotlight not start out as a point?
Date: 23 Jul 2014 17:37:29
Message: <53d02b19@news.povray.org>

> I'd like the start to be of some arbitrary radius instead of a point. How would
> I do this?
>
>

You can always make your spotlight an area_light.
As you should be using version 3.7, adding area_illumination will make 
it all the better.
Don't forget to take advantage of the adaptive feature, and note that 
the value after adaptive is NOT a boolean: Using adaptive 0 don't turn 
the feature OFF but set it to start with zero subdivisions, or start 
sampling with only the 4 corners. Very good as a start point... In some 
cases, it may even be good enough for your final render.
Altough area_light take longer, and area_illumination still some more, 
it's relatively fast.

If you have the time, replace the light with a disk with some high 
emission value at the bottom of an open cylinder and use radiosity. Take 
advantage of radiosity adaptive sampling by using importance. The 
radiosity based spotlight will need importance 1 while you can set a 
default importance of 0.00001 and samples 10000000, 500000000...
This cause the general objects to get, on average, about 100 samples, 
but the spotlight will get the full 10 000 000 samples.

Both can be combined. In this case, the radiosity settings can be much 
more relaxed, making things go much faster.



Alain


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