On 04/01/2011 01:32 PM, Trevor G Quayle wrote:
>>>
>>
>> OK ... so here's what I've come up with and it seems to work.
>>
>> #declare Intensity = function (LD,FD) { 1/(2/((1+(LD/FD))*(1+(LD/FD)))) };
>>
>>   From your example I used LD=2400 and FD=4.5 and get 142756 and some
>> change ;-) ... If I missed something feel free to set me straight as I'd
>> like to include this in [3.4.7.9] along with a small narrative.
>>
>> Jim
>
> That's exactly it.  However I would maybe modify it slightly for presentation.
> You can simplify by removing the double reciprocal (just invert the original
> equation).  Also, this is true for fade_power of 2, I would leave fade_power as
> part of it for completeness and to avoid confusion:
>
> #declare Intensity = function (LD,FD) {pow(1+(LD/FD),FP)/2};

LOL ... thanks fer makin' it purdy ;-)

>
> Also I would perhaps call it 'intensity multiplier' or similar.  If you want a
> base intensity of 2, you would multiply this factor by 2, etc.
>
> -tgq
>
When you get a second I'd appreciate a little QA:
http://wiki.povray.org/content/Documentation:Reference_Section_4.4#Light_Fading

Thanks :-)

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