I’ve been watching different V-Ray tutorials on creating metal materials such as Chrome and Aluminum and the IOR settings differ greatly from tutorial to tutorial! One says to use a IOR values between 8 and 20 and another says between 20 to 100? Then there are IOR lists that say Chrome is 2.4 and Aluminum is 1.44, which does not make intuitive sense to me.
Which range do you suggest I use?
What would you suggest for Aluminum?
Hi Bart,
I always went off zap’s mental-ray post on the subject: http://mentalraytips.blogspot.com.au/2007/10/making-better-metal-with-miamaterial.html
the same holds true using fresnel and an IOR of 25-50 in vray as far as I have found. I have never found the scientific numbers, I just go on “look” :")
Chris
http://refractiveindex.info/?group=METALS&material=Aluminium
as this website shows.. ior really depends hugely on light wavelength, so that is why its hard to give an accurate figure.
just for reference, visible light is approximately between 0.4 and 0.75 um
You’re after complex IOR’s or conductive
Check this out:
http://www.chaosgroup.com/forums/vbulletin/showthread.php?53203-IOR-on-fresnel
After doing some testing a few months ago, I found that using Vlado’s suggestion of a ramp (plug the info sampler node in a ramp -facing ration in Vcoord- then plug the ramp in the reflection colour), seemed the best solution for now.
As it’s at the edges for metals where it goes wrong (imho) with fresnel values.
Thanks RobPhoboS for the interesting links about the the custom BRDF. I’m going to look into the FXPHD - MYA214 course to learn more.
I’m familiar with the ramp / facing ratio approach, but agree it’s not very elegant, I’ll be waiting for the new implementation also.
yeh, vlado please a “K(Extinction coefficient)” value for vraymtl. 
No problemo 
Once you’ve done a couple of tests you can save a setting for specific/typical metals and it’s better than just sticking with high a value fresnel (imho).
I’m HUGELY far behind with my own tests unfortunately so I’ve got to start over with soo many things, argh but this is high up on the list to get ‘sorted’ in my workflow.