3D Studio Max R5 radiosity and logarithmic exposure control

[KOryH]

AAhhh the question of the ages.
I have been waiting on the mountian for the answer, but no one has spoken.

[Maven]

If you are looking to just fake the radiosity then just use the Light Tracer plugin.

[zicher]

The relationship between lights, radiosity, light tracer and exposure controls need to be understood a bit.

First, remember that the logarithmic exposure control needs to be used only if you have photometric lights in the scene and/or you use radiosity.

If you have only standard lights and light tracer there is no need for any exposure control at all.

The logarithmic exposure control has been introduced only to bring the extreme light ranges created by photometric lights into the range acceptable by the output file format. It helps in bringing overexposed areas down to an acceptable range, and darker areas up a bit.

Internally 3ds max uses much higher ranges (48 bits) than any monitor can handle (24 bit). The exposure controls compress that range (linear or logaritmic way) into the limited 24 bit range.

Rob
Discreet

[NNNSlogan]

That's what it says in the manual.

It still overamps the heck out of the red in my render, and no amount of tweaking seems to get the end results in the render to look at good as the viewport. The radiosity solution as set up by the logarithmic exposure settings looks great in the viewport as far as shading and color balance go, then looks awful in the render.

[zicher]

Some images may help...

There are many other factors that can affect the image. Suggestion is to start cutting down geometry and lights to narrow down the problem.
Remove filters, volumetric stuff, transparent objects, environment maps, etc etc.

Do you see an excessive color bleeding? Are your lights colored? What kind of shadows are you using? Are you mixing photometric and standard light? Are you using the Adv. Lighting Override material?

So far, most of the problems I found with Radiosity were my fault. I don't exclude that something in your scene may trigger an odd behavior, but I need more info to help.

Rob

[NNNSlogan]

"There are many other factors that can affect the image. Suggestion is to start cutting down geometry and lights to narrow down the problem.
Remove filters, volumetric stuff, transparent objects, environment maps, etc etc."

The geometry is a single sphere. The lighting is photometric sun and sky, necessary for the radiosity effect. There are no filters, no volumetric anything, no transparent objects, no environment maps, no etc.

"Do you see an excessive color bleeding? Are your lights colored? What kind of shadows are you using? Are you mixing photometric and standard light? Are you using the Adv. Lighting Override material?"

The reds are super intense. The material I'm using is just a red bitmap in a simple material, since you can't do it without something in the material. Shadows are not checked in the Sun light. I am not mixing photometric and standard light.

[NNNSlogan]

http://www.dragonsandmonkeys.com/maxcap1.jpg http://www.dragonsandmonkeys.com/maxcap2.jpg

[zicher]

Ok, I see now....

Check your sun light. If you used the default settings the intensity will be in the 80000-90000 range.

Then try this. Bring up the Brightness (in the log exposure control) to the default level of 65.

Turn on the Exterior Daylight. The extreme intensity of the sunlight requires it.

I don't have Max on this machine, so I can't set up a similar scene and check.

Rob

[NNNSlogan]

Sun intensity was set at 7432.24

[NNNSlogan]

That takes care of the red overamping, but the scene ends up looking bad with those settings, whereas the previous settings made it look the way I wanted in the viewport, but not in the render. This way it doesn't look right in either the viewport or the render.

I'll have to tinker some more I guess.

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