[Ernesto]

I am performing some tests to find out how the light is being distributed in the diferent emiting surfaces, but cannot understand it clearly by what I can see in the images. That is why I decided to ask, perhaps someone that has already debunked this topic.

I understand that we have two types of emiting materials that distribute their light in two diferent ways.

1) Absolute Intensity, for instance I have a 100w material. This means that if I have 4 objects of diferent sizes, each of them will emit 100w no matter the size nor shape. This could cause the density of the light, to vary accordingly to the size of the object. Then, a smal object may concentrate the 100w in almost a point, meanwhile a huge object would emit a dim light all over its surface, which will be equivalent to 100w, only that it would be distributed is its area.

2) Relative Intensity, in case I have a 100 lux material. Since Lux are Lumens/m2, they will distribute accordingly the surface area.
If I have the same 4 objects each of them will emit a diferent amount of light depending on the area of each of them. On the other hand they will show an equivalent brightness since the light will be proportional to the surfaces. There would be no concentration in any place.

My questions are:

a) if I have separated (separated in space) surfaces in the scene, but that were converted into a single object (as we used to do in V1.7 to get a single multilight channel for them all) what would be the behaviour?

b) what happens when we use multilight?
All the separated objects now looks a single object. (perhaps it only looks like, but they remain separated?) Does this change any of the previous parameters?

Ernesto

[renbry]

Multilight (and emitters) are now material-based; meaning 100 objects with the same Emitter material would follow the distribution rule from the material. Multilight would also only show one channel.

If you combine the objects they would be considered face-assigned materials and would still obey the above rule (it would just be a bit confusing to deal with and I/we don't use face assignements if possible)

Does that make sense ?

[dariolanza]

Hi Ernesto,

Simply assign your emitter material to all your objects and all of them will work as one big emitter, but with a single common behavior (relative or absolute depending on how you define that emitting material).

Greetings

Dario Lanza

[choo-chee]

hope this helps:
small object will emit a strong point of light with sharper shadow.
big object will emit (with the same emitter) weaker point of light with softer shadow.
so for a bulb I use a small plane like 0.5X0.5 cm but for indirect fill light I use 10X10 plane.