lighting a large interior

#1

hello all cg’ers

I’m hoping to get a little help with some lighting issues. I am trying to do an interior render of a large concrete hall space that is lit mainly from a wall of frosted glass panels. I’m trying to simulate a large amount of natural light entering the space from the clear glazing (left side) and the frosted glazing (opposite camera), to get a more natural look, although i thought I may need to add some interior point lights in areas far from the wall.

basically, I’m trying to bounce as much light around the interior as possible. So in a second attempt, I tried to add an area light that has no intensity, and only emits photons.

I dont have much experience in successful interior renders, and I’m 0% on GI success.

Settings:
-color management ON - Linear workflow - sRGB input / sRGB Linear output -->32 bit float open exr
-Physical sun/sky used (lens shader deleted)
-Final gather on medium quality, 200 rays
-No gamma correction on textures (I think its not needed since my input is set to sRGB?)

second render has an attempt at inserting an area light the size of the translucent glass wall, just on the inside edge, with 0.01 intensity, emitting photons. GI settings are at default. I couldnt change the number of photons emitted, i dont know why the box was greyed out. I just got a milky haze in this version.

The interior is huge, the floor to ceiling height is 3.25 meters. My maya units are changed to meters.

I’d greatly appreciate any help. thanks in advance!

first try - only Final Gather

second try with GI and added area light

#2

I added an mi_portal_light node on the area lights, which I just discovered - -it helped a lot, but its still not at a professional level.

Any mental ray users out there have advice?

#3

start with the overal environment light to get that ambience…and see everywhere

#4

Hey nurbgurb,

Materials and lighting go hand in hand. It’s important to realize that even the roughest surfaces have even the smallest amount of reflection on them. If you increase and blur the reflection on the pillars, railing and ground a little bit I think you’d be surprised how much further your image can be taken.

It looks like the pillars are encased in fog. Make sure you enable shadows on the portal light.

-Dan

#5

Dan, thanks for the reply. Here is an updated version of the view, with the portal lights. (people are photoshopped in)

The concrete on the columns is the same shader as the floor. I used the color texture to drive reflection glossiness as well, to try to get a more realistic look. I’m trying to get better with materials, but need improvement. The columns still seem a bit cloudy maybe - the projection is too compressed in the y axis.

I replaced the rail with a metal preset in mia_material, and i think it helped a lot. I dont have a portal light coming thru the metal screen on the left, since direct sunlight is coming thru - and the metal screen is coming out black - it has a great looking brush metal finish. Do you have any ideas on how to get good ambient light on the backside of the screen?

No global illumination in this render, just final gather with 2 diffuse bounces.

#6

I am trying to add GI again, and its adding the same interior “fog” - do you have any idea why? I’m using almost all default settings

#7

I can’t be certain but maybe the radius in your GI settings is to high. Posting an image of your settings could be helpful.

To test, try disabling final gather and see how big the GI dots are in the render. You may need to decrease the photon count to be able to see the photons clearly enough.

#8

thanks a lot Dan. I dont know exactly what my settings were, but they were near default - I know that the radius size was set to automatic (zero). I just measured a distance and realized that my model is 1/100 the size of actual scale!

this probably has an effect here. I know that I can change the units in the settings, but is there a way to scale everything together in Maya? The problem is that I was importing the model from Rhino (in meters) and had maya at the default (in centimeters)

edit: i just grouped everything, scaled it up manually (some objects didnt play along well) and did a test render, and the GI doesnt seem to be too different from the 1/100 version.

#9

Glad to help out. Scale’s definitely very important. If you don’t have any rigs or unconventional grouping you should be able to group the entire scene and scale the group.

#10

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