GI Photon Light Leaking and Tone Mapping

[nicknitro]

 

 

I have just started doing some lighting tests on my spare time to practice and have a few questions.

 

Specs: Max 2010 Mental Ray

Lights: 1 Directional Light (Sun) 2 Free Area Spotlights generating photons (placed at both windows)

 

Problems:

 

I get light leaking in the corners of my room model which I know is a common error but was wondering the best way to correct this.

 

Gamma correction + Tone Mapping - I have been trying to Tone Map my images because when I save out my Image as the one you will see (jpeg) it saves out a lot darker then it is in the Render Window.

Gamma set to 2.2 Gamma input and output set to 2.2 as well.

 

MR Photographic Exposure Control

Tone Mapping - Exposure Value 10

Physical Scale - Unitless set to 8000

 

I do understand there is a bunch of splotchyness on the wall with the windows. This is just preliminary lighting tests to fix issues (like the ones listed haha)

[Justin Hunt]

generally light leaks are a caused by either single sided geometry, photon sample radii being too big or photon energy being too high.

 

Try using the mrsun and sky and mrportal lights, as they are designed for this type of lighting setup.

 

Then use the Physical units for the exposure control.

 

To start with leave the photon sample radius OFF (ie let mr decide how big it should be) then try with your own setting, keeping it reletive to the size of the room.

 

Also be sure to use FG with 0 bousnce to clean up the photon solution. Draft preset is good enough.

 

For some reason your attatchment isn't showing up so I have covered the "common" problems.

 

jhv

[nicknitro]

Thanks so much I really appreciate it I will go over your comments and try to set up those settings when I open the scene up next.

 

The photo isn't showing up huh? Hm it shows up on my comp....

 

 

Does this work?

[Justin Hunt]

Yes it is working, it must have been the work firewall,

 

Those leaks look like something is wrong with the geometry.

 

The other thing to set with the MRsun is the Photon emit radius. Set it to be slightly larger than the window and then focus it through the window itself. This will force the all photons shot from the sun to be focused into the room instead of spreading them all over. Also means you can shoot less photons.

 

jhv

[nicknitro]

Ok I will try the Mr Sun and Sky with portals next and see what kind of results it gives me.

 

thanks a lot I appreciate it.

[Justin Hunt]

I you like , shoot me the file and I can take a look. I am interested in what is causing that leak, as it looks more like direct light than a leak.

 

PM me if your interested.

 

jhv

[nicknitro]

Justin

 

What I actually did as was I forgot that there was a modeled tall wood closet in that corner so what I did was just unhid it

 

I rebuilt the box aka the room to see if that was the issue and was still getting that bright spot in the corner. All verts were merged and whatnot. I think it maybe be my direction light acting crazy.

 

Ill be posting more WIP's soon on this project.

 

Thanks for your time man I appreciate it

 

 

EDIT: New Test Render (about 20 minutes of messing with the lights)

 

Edited March 18, 2010 by nicknitro

[bobaki]

Thank you guys..by reading the replies and the issues that people been having, i had the same issue and i got it fixed..By adjusting the Global Illumination Radius...The higher the radius the more light leaks it will be in the scene..

 

Btw i am using Autodesk Maya 2011 and Mental Ray..

[Jennifer]

Try turning off FG to see how your GI solution looks without the cleanup. If you see a lot of splotchiness then increase the "Average GI Photons Per Light" to get a smooth result before using FG. You can shoot millions of photons if needed. Good advice above on using the Photon radius setting for Daylight, and adjusting the Radius value.

 

Photons don't like to go around corners, so adjusting your geometry to make sure interior objects aren't poking through to the outside and ensuring you have a sealed shell around the scene can help.

[bobaki]

guys...i am getting the same issue..however when i crank down the radius, it kinda minimizes the error and then when i crank the photons, i am getting the samething..

I have extruded the edges so it had more thickness to it but i dont know what is causing it..