LuxC4D 0.06c

[jeanphi]

Hi,

The LuxBlend export script has an option to clamp RGB values. However you must not clamp all RGB values (for emitters, they don't need clamping, and RGB colors applied to fresnel based materials don't need clamping otherwise you'd get dark glass for example). LuxBlend currently doesn't have those refinements so this feature isn't used much.

Jeanphi

[Dade]

How does this work in other renderers, such as Blender or Maya?

I'm not 100% sure but Luxblend should have an option to cap the colour values to 90% (it doesn't scale them, just cap the values).

[abstrax]

One thing to make note of though - 100% white doesn't exist in the real world. That would be a surface that reflects 100% of all light hitting it. The whitest white you'll encounter in the real world reflects *maybe* 80% of the light hitting it. Keep this in mind - C4D's conventions don't really simulate real-world conditions. I've done perfectly reasonable renders of "white walled" rooms in LuxRender where the wall colour was 50% grey in C4D.

Ok - I'll play with the different modes and post the results later today.

Anyhow - the question (from a usability standpoint) is, if there should be some sort of "adapted conversion" between a non-physical editor and a physical renderer. Otherwise you can never use any kind of (editor) preview for your final rendering, which would turn the renderer useless IMHO.

If Lux needs a white value of ~80% (or less) for the brightest natural white, then a 100% C4D-white should convert to that. I know this depends a lot on other factors such as lighting and camera settings, but if a renderer should be useful for any person from a creative rather than a technical background, than this is inevitable... IMHO.

How does this work in other renderers, such as Blender or Maya?

Cheers

Dirk

Hi Dirk,

I think there is still a misunderstanding: It's not that Lux "needs" a 80% grey to get a bright natural white. You can get a bright white with 50% grey as well as with 20% grey - it's just a matter of exposure time. Lux just behaves like a camera: If you expose long enough even the darkest colour (except 100% pure black) becomes white eventually.

And yes you can get good results with 100% colours, too. The problem is more a numerical one: In some circumstances you can get fireflies, which are caused by numerical degeneration while light bounces between perfectly white surfaces.

I have thought about capping or scaling colours during export. There are two reasons why I haven't done it yet: I don't know where to cap (at 80%, 90%, 95%, 98 or 99%) and I don't know how to cap textures (which can be 100% white, too) without adding extra load (by putting all textures into a scale texture) which slows down Lux again.

And I didn't think it was necessary. All the above problems are mainly tone-mapping problems and not colour problems. That's the reason why by default the next version of LuxC4D will use "maxwhite" as default tone-mapping (check your Lux mailbox ), which I hope to release this weekend.

Cheers,
Marcus