what it does is to let you compose the final result by tweaking directly the color for fg emissions and
irradiance… the fgemissions are controlled with something like the raytype in xsi or the one made by
szabolic… here you get also an HSV color corrector to better manage the effect… it simply catches the fg
rays and return the shader after implemented the c.correction… this happens only for the fg and photon
rays… that is…
- use the emission tab to get fg into the scene… basically how much that color will
contribute to the final fg/gi solution… enabling emission will let you overwrite the standard emission for
the shader… if you have already an emitting material, like a constant or one with incandescence enabled
you can tweak that ‘emission’ with emission tab params… if not you can specify directly a 2nd color just
for the fg calculation. the scene example is when you have a sphere dome ‘emitting light’, here you ctrl
how much light will be in the scene from the sphere, how much is saturated that color and so on… by
tweaking the saturation you’ll get rid of overbleeded skies while maintaning the right colors visually.
the irradiance otherwise ctrl how much of that fg solution will be showed on your material… and it is in all
the aspect the same as the irradiance controls you’ll find under the maya materials (mentalray tab)…
that for using this one you’ll have also to [color=white]put to black… here the default values act really as the default [/color]
from maya… what does the irradiance function? compute the irradiance, multiply that for the diffuse color
and then add the whole to the final color for the mat… here you have the possibility to use a different
color from the diffuse one… with maya mats the diffuse color is inherithed from the diffuse slot… here you
can specify a different one… if not should be the same as your diffuse… and also you can fine tune your
colors mood under a fg/gi env… that is different than just tweak the diffuse color… so in general…
- use the irradiance tab to fine ctrl the fg solution on that material, to control overexposures I have
implemented a really fast and smart tone mapping algorithm[size=2] that without have to make a whole pass, [/size]
can get rid of overexposed zones while maintain the same ambient and color scheme by exposing the
virtual sensibility and aperture for that color conditions (the second sphere is just tonemapped).
the scene example is when you have already made the light and gi setup but you find your obj too
overexposed or maybe to dark and not so in contrast with the whole scene and you wanna simply
color correct them as you were in a non gi env.
obviously you can enable both of them for your materials.
the basic setup is:: put to black the irradiance for your maya material, plug it into the input of the
ctrl_irradiance shader, enable irradiance and then tweak your params.
a little addendum is to consider the photon shaders in maya. that are a litte weird… each illum mat has
already a photon part… but this one will work only if the last shader will be that material… that is if you
use just a simply colorpasstrought node… it wont work (maybe use the surfaceshader shader…)…
so I exposed the maya_photonsurface shader and you can simply use this one and plug it into the
photon slot for the mr mat and get full ctrl over your shader net… it is true that the params there should
match the ones of your diffussive mat… but better make a phen to link those then use the maya buildin,
at least for me. do not (re)register in the mr rayrc file… just put in the include folder.