Question regarding Light multipliers - help

[Cesar R]

I am intrigged....

 

In an MR scene (interior render)

I have the following lights

 

1 MR-Spot = SUN

1 Skylight ( I am not using the "daylight system")

1 or more mr light portals.

 

Each of these lights has a multiplier, I find sometimes that I am going higher than 1.0 and depending on the scene I am have all these weird combinations. On the attached scene for example the "sun and sky" are set to 3.0 the portal to 1.0

 

In addition, you also have have the GI solution and Fg solution multipliers. Should these be set to 1.0 all the time? or can I play with them depending which solution I want to contribute more the scene lighthing? (makes sense)

 

What about the color?

I set my sun to "yellow"

sky to "light blue"

portals to while.... since the light goes through the mr portal, is it going to be WHITE?

 

If someone can help me warp my head around this it would be great !! I can post the scene if needed, but for some reason the exposure control preview always comes out black...

[mattclinch]

The mr (mental ray) Sky Portal object provides an efficient method of “gathering” existing sky lighting in interior scenes without requiring high final gather or global illumination settings that would result in excessively long render times. In effect, a portal acts as an area light that derives its brightness and coloring from the environment.

 

so the colour is defined by the environment - ie. your skylight, assuming you have the 'color source' in the advanced parameters set to 'use existing skylight'. the 'color' option simply acts as a tint to the existing colour source - so white will not change the colour temp of the light from the portal.

the intensity is also linked to the skylight in the same way - the multiplier value is a multiple of the skylight intensity.

.

Use existing Skylight - Uses the skylight. By default, with the mr Sky light using the mr Physical Sky environment map at their default values, this tends to give a bluish illumination, as with real-world skylight.

 

i would try as much as possible to keep every multiplier at 1 for physical accuracy. if something is too dark you should change the mr photographic exposure value first, and try to get a good balance with that, only altering the intensity of sky portals to fine tune and balance the lighting.

certainly the GI and FG multipliers should be kept at 1.

 

i would consider using a full daylight system with the sky portals rather than a separate skylight and mr-spot. i have always found this a much better light solution.

[Cesar R]

hi thanks for your reply, where are you getting those quotes from? I wast tying to follow for sintance on the past where there should be a button for "Use existing Skylight" ? but there isnt. I am in Max Design 2011. I did notice that with in the Daylight system you can choose to use a MRSKY or a SKYLIGHT. The Mrsky doesnt have any color source, whereas the skylight does.

[Cesar R]

Duh,.. the help file ! I miss the day when Kinetix would ship a manual w the software !!!

[Cesar R]

I guess my question in.. Mentalray has made it so easy to make sky and sun, however before this was incorporated into the software I am sure the sky and sun where modeled by using two different / separete lights. Something like i was originally doing?

 

I m reading the help file but I have gotten as far a getting the MR enviroment map into a slot in the material editor, but I cannot indentify how to change the sky color so that is it not so blue. I guess another alternative is to change the tint of the mr portal, but I feel the blue from the sky is too strong. I am looking down the hallway and I dont see any bue light.

[jinsley]

I guess my question in.. Mentalray has made it so easy to make sky and sun, however before this was incorporated into the software I am sure the sky and sun where modeled by using two different / separete lights. Something like i was originally doing?

 

I m reading the help file but I have gotten as far a getting the MR enviroment map into a slot in the material editor, but I cannot indentify how to change the sky color so that is it not so blue. I guess another alternative is to change the tint of the mr portal, but I feel the blue from the sky is too strong. I am looking down the hallway and I dont see any bue light.

 

why don't you drag and drop the mr physical sky shader into the material editor? there are some options available there to manually set the tint... the other option would be to use an environment map in the environment slot.

[Cesar R]

why don't you drag and drop the mr physical sky shader into the material editor? there are some options available there to manually set the tint... the other option would be to use an environment map in the environment slot.

 

yeah that is what I think I am doing and I am lost of the color of the sky, unless I am missing something,

see attached

[jinsley]

uncheck the "inherent from MR SKY" and then you can play with the non-physical tuning paramteters...

[Cesar R]

^ yes that works. Too bad yo can only go between blue and yellow for the sky.