I am obviously not understanding something related to light for a ray tracer.
A bit of a context:
My question is: in room at X degrees Celsius, for ray of light with an originating linear RGB color of (0.4,0.6,0.6), with an originating power in Watts of 750W, at what distance would it become invisible, with a color (0,0,0)?
My limited understanding tells me that light intensity decreases at the rate given by 1/(d*d).
At 500 meters: (what I am about to write is so ridiculous, but let's do it) So we would have A = 750 / (500*500) = .765 and put back in sRGB I multiply by 255
(A * 0.4, A * 0.6, A* 0.6) = (0, 0, 0) approx.
500m look way to high for a 750W light to reach a sRGB color of 0. So my calculation is wrong from the start.
My experiments so far:
Using Blender, with a white spotlight of 750W oriented at 90d, it takes approx 80m for it to be invisible to my eye, on a white plane.
We are talking of very non scientific measure, obviously but it gives an order of magnitude: 80m is far more plausible.
Could someone tell me how to correctly calculate the power and color of a light, from its originating color at distance X meters?
My current decision is to use a completely different light calculation and it yields visually correct results. Instead of starting with known units, I just decide the length in meters a ray can have and apply my attenuation according to the cumulated distance.