Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: danio1011 on 2018-08-16, 18:23:02

Title: IOR for unfinished wood?
Post by: danio1011 on 2018-08-16, 18:23:02

Hello,

I often have to do raw, unfinished wood exteriors.  I find with an IOR of 1.52, even with a low reflection glossiness and bump, I get a bit of a plastic look.  I remember hearing that unfinished wood is a 'lambertion' and didn't have reflectivity in the same way.  Would it be physically correct to set the IOR to 1.0?  Or is that crazy talk?

Thanks,
Daniel

Title: Re: IOR for unfinished wood?
Post by: Njen on 2018-08-17, 04:29:03

An IOR of 1 is technically a vaccum, even air is about 1.000293. No dielectric would be close to an IOR of 1, as most dielectric surfaces are roughly between 1.35 to 1.7, with 1.52 being near the most common value. I really wouldn't go lower than 1.35 for rough wood.

If you are looking for a rougher wood, try adjusting the glossiness and bump of your surface.

Title: Re: IOR for unfinished wood?
Post by: matsu on 2018-08-17, 13:59:19

Make it really rough (like 0.25 or something) and add a bit of bumpmap. That usually works for me, anyway.

Title: Re: IOR for unfinished wood?
Post by: Nekrobul on 2018-08-17, 13:59:43

1.52 is perfectly fine for the wood.

But wood itself is very tricky and there is 80% chance that you would be needing to use blend fresnel falloff material trick to make proper wood texture.

Title: Re: IOR for unfinished wood?
Post by: danio1011 on 2018-08-17, 19:00:28

Thanks all for the feedback!  1.35 and low ref. glossiness\high bump is working pretty well.  I'd be curious about the blend fresnel falloff trick?  Is this to emulate figure or the 'fuzz' of rough wood (similar to fabric)?