irradiance

[bertrand]

i m working on maya 7 and when i tweak the irradiance attribut in material tab i see no diferrence. Why? it is not supposed to change something and if it affect nothing why it s here?
bert

[ghostlake114]

Turn on Final Gather to see the result :)

[bertrand]

thanks but i Know that it should affect the final gather;) .the trouble is it don t.i post 2 jpg one with irradiance set to white and the other to black all the objects got the same lambert . So as to spot a maybe trouble i change the initial lambert to a new one, i check then uncheck the defaut light and i change the material type to blinn no difference so my conclusion is irradiance don t work in maya 7 or don t affect mental ray fg calculation. So bug or missunderstanding of the use of this attribut.
bert

[Wish]

And were your light is?)))
Make the incandescense of the PLANE higher!
________
Simca Aronde (http://www.dodge-wiki.com/wiki/Simca_Aronde)

[bertrand]

in this scene ther is no light, i kep it as simple as possible, it s just to see what is the irradiance attribut. So there is only diffuse shader, and mental ray fg. but when i change irradiance on the lambert nothing change.
I was supposing that the irradiance was use to help some object to participate more to the fg calculation. And irradiance color to bring the ability to give a color to this participation. the irradiance color give something bur the irradiance do nothing. So if someone can show me a set up so as to see the use of irradiance?
bert

[bertrand]

is there no reponse? on what is irradiance and how to observe the way it work?

[CTZn]

Maybe the point of Wish was relevant. Maybe irradiance is related with how much light is multiplied after diffusion on the surface... That's not the same as ambiant or color composants of the shader...

[bertrand]

I ve been trying to use irradiance with onlyfinal gather because it s a final gather related option. So i do not use any light. As say Wish i try to raise the incandescence of the above geometry but nothing change (exept more light of course) maybe because my geometry is grey.But i will add light so as to see if i got a difference.But if someone can set me up a scene where the tweaking of irradiance make a change, i will take it :p
bert

[bertrand]

ok i do some new test.
irradiance seem to controle the way the material of an object emit light. it replace the use of incandescence in traditional maya shader.no light is required. nor increasing incandescence.
and you can use it to increase color bleeding with only fg. and it only work with a texture or a ramp attached to it as far as ive seen.if some people got some complementary info...
bert