Inverse Square Law for Lumipolys

[khan973]

Hey,
I was wondering If somebody could script / create a node that would be able to apply Inverse Square law on a surface.
We would just need a distance parameter (or input) then, we can plug it to the Luminosity channel and get our lumipolys to react like Area lights.
Currently, I'm trying with Layer gradient.

[khan973]

That was a stupid thinking, it can't work as the surface isn't volumetric and remains in one particular distance...
But maybe all th other surfaces around could be affected by the luminosity of this lumipoly according to it's distance... Sounds more complicated and painful though

[jure]

I think you can do this with nodes.

First try to match lumi poly intensity to Area light intensity at 1m/100%. Then add necessary controls to lumi poly luminosity channel. You could also hook it up with distance to object or anything else you want...

But ofcourse there are no controls for falloff type for lumi polygons. They will always behave realistically with inv^2 falloff.

[khan973]

That's exactly what I did, but it cannot work.
Light fallof in Lightwave can be controlled and it means that it evaluates how it affects objects based on the distance from the light center.
With lumipoly, I think you can't control that parameter unless you choose on each other surface how it's affected by the lumi surface based on their distance from the lumipoly's surface.
It seems to affect it linearly anyways

I tried to change the light intensity with the distance, but if I do so, the whole lumipoly surface will have one fixed value and will cast light linearly from that value.

There might be a way but it's probably beyond my understanding of nodes.

[Captain Obvious]

As I posted in the other thread...


Luminous geometry ALWAYS has inverse square falloff. You can change this with nodes, though: use the spot info's 'ray length' or whatever it's called, plug it into a gradient or something.

[khan973]

Aw really?
Cool man, that's a really good new!!! But how comes?

[Captain Obvious]

Basically, because luminous geometry are not LIGHTS, as such. Imagine if the moon was twice as close to the earth! It would appear four times bigger, and even though the surface would appear to be the same intensity, the increased size means that four times more light would reach you -- the total intensity would be quadrupled. Same thing with luminous geometry. If they're further away, they will appear 'smaller' to the surfaces being illuminated, and thusly cast less light on them.

[khan973]

Thats makes a lot of sense to me it even appears to be really obvious. You haven't stolen you name!

[brownie]

I used to have so much difficulties to deal with fallof that I wouldn't claim for an addition in luminous sufaces as an option!

[khan973]

You won't have to use it if you don't want to

[steven444]

it seems to b inverse square law of difficulties