Setting Up GI using Radiosity in 3ds Max5

Brian C. Morris - American College of Thessaloniki tutorial


In this tutorial you will use the Photometric Point Light and the Radiosity Engine to illuminate the Radiosity_Stockroom_start.max scene with Global illumination.


The Task

You must get a realistic Global illumination render with light bouncing and color bleed. When I first wrote this tutorial the optimized renders took about  6 minutes on a pentium4 1.2gh machine with 1gb Ram. You are most likely using s faster machine by now (like me) but you should always try to optimize anyway. The output size is already set up in the file. Check feedback at bottom of max UI to check render time for both cameras. Use the 2 cameras in the scene to render both views, try not move these cameras so it will be easy to compare the images.


The file is setup with System Unit Scale in centimeters and Display Unit Scale in meters. Don't change these settings or the Global Subdivision Settings will not match  in step 2 and proper scale is very important for Max's advanced lights and Radiosity.


Lets Go:

1.    Open the max file Radiosity_Stockroom_start.max, remember to "Adopt the file's unit scale" if asked. Lets add the Target Point Light . Activate the left viewport, activate the Target Point light creation mode, now in the left viewport mouse-click/hold in the light fixture, drag straight down to the floor and release.  Go the the modify panel, Turn on the Adv.Ray Traced Shadows. Also, make sure the light does not intersect the light fixture geometry (see image below for position and settings).




2.  Activate the Radiosity engine: from the Rendering menu à Advanced Lighting, or just use the 9 keyboard shortcut. Now input the settings below.


initial Quality to 85% if not already.

Refine Iterations (All Objects) to 3

Filtering to 3

Enable Global Subdivision Settings with Meshing size 1.0 m




3.     Calculate a Radiosity Solution by Clicking the start button. This may take a minute or two depending on machine. When the calculation is done you will see the meshing subdivisions and a radiosity lighting preview in the viewports. Not bad, lets see how long it will take to render though?




4.     Do render from Camera01. You should get a render that looks like my below. Its too dark but we will fix it in the next step. For now load the render into channel A of the Ram Player and leave Ram Player open.




5.     The render was a little dark. You need to Add a Advanced Material Overide material to Walls_floors_Ceiling material to fix this. So find the Walls_Floor_Celing material in the Material Editor click on the “Multi/Sub-Object” button to add a Advanced Material Overide material. (make sure to keep the old material).




6. Now to input the some initial settings in the Advanced Material Overide material


Reflectance Scale to 1.5

Color Bleed to .4




7.    Now that we have added the Lighting Overide material the radiosity solution invalid. Click the "Reset All" button and then the "Start" button to Re-Calculate the Radiosity Solution.




8.   Do render from Camera01. You should get a render that looks like my render02.jpg. Now load it into channel B of the Ram Player and leave Ram Player open. Compare it, better but still to dark.




9.   Go back to the Advanced Lighting dialog box, click the Setup button (next to No exposure control selected). This will open the Environment dialogue window, now in the Exposure Control rollout chose Logarithmic Exposure Control and leave the default settings.




10. Do render from Camera01You should get a render that looks like my render03.jpg. Now it’s a bit too light, with a lot of color bleed. Load it into channel A of the Ram Player. Do scene hold or save.




11. In the Logarithmic Exposure Control parameters bring the Contrast up, and the Brightness down a bit. Notice the change. Then from the Advanced Material Overide material bring the Color Bleed down a little bit. Again re need to recalculate the radiosity solution, click the "Reset All" button and then the "Start". After you have a new radiosity solution do a render.




12. Repeat steps in 11 until your render looks like my render below. That's it for the basic setup. I hope you get the general idea.






If you need even better results and you don't mind waiting for renders you can add an additional refinement stage known as Re-gathering. Its located in the Rendering Parameters rollout of the Advanced Lighting (Radiosity) dialog. The "how-to" details are for another tutorial but below is a render and time comparison.

Machine: Time on Dual Xeon (6gh total) with 2024mb Ram

No Re-gathering = 0.00.03

Yes Re-gathering = 0.01.21


© Tutorial by: Brian C. Morris