Jim Holsenback <jho### [at] povrayorg> wrote:

> I've been using:
> #declare LightDist = vlength(LightPos);
>
> as my value for fade_distance, Which is WRONG ... I want a smaller value
> for that and up the intensity of the light source to compensate ...
> @Christoph: Did I get that right?
>
> Jim

This is something I learned from doing the matinee scene.

What I have ended up doing, is set a relatively small fade distance (say the
size of the light itself).  I then figure out what general value I want it at a
certain distance (i.e., distance from light to your object or scene centre).
Then use the formula given in the help to back calculate the initial intensity.

For example, in my matinee scene for the projector, the distance from my
projector light to the screen is about 2400, I set the fade distance to about
4.5.  Back-calculating to get a value of 1 at the screen (calculate the
attenutaion value and take the inverse), gives an initial value of ~142,000!
This seems very high, but it works out well because of the samll fade distance.

-tgq

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