Custom fresnel curves in Softimage, is that possible?

Discussions regarding Materials, Material-Compounds or Shaders, etc.
ronaldomiranda
Posts: 38
Joined: 04 Mar 2013, 13:01

Custom fresnel curves in Softimage, is that possible?

Post by ronaldomiranda » 25 May 2015, 21:45

I recently read this article about custom fresnel curves for more realistic shading:

http://therenderblog.com/custom-fresnel-curves-in-maya/

and the same idea is on this tutorial for shading metals in modo:

https://vimeo.com/ondemand/shading1

wondering if its possible to create such curves in XSI, regardless of renderer (MR, vray or Arnold)...

User avatar
Mathaeus
Posts: 1750
Joined: 08 Jun 2009, 21:11
Location: Zagreb, Croatia

Re: Custom fresnel curves in Softimage, is that possible?

Post by Mathaeus » 26 May 2015, 10:21

Should be incidence node, plugged into scalar math curve. That's approximate translation of Maya sampler info and remap value.
Another story is, *what* you will remap with this. Is it a plain mix of diffuse and reflection shading, or there is a sort of dumping on top of everything, like energy conservation. Or there's something else in mix, too...
Anyway, it's interesting that in entire article ( if I'm correct), no word about RGB Fresnel, it seems he just considers as 'enough correct' to have a monochrome blend. Put numbers into equitation, and you're there....:) For small comparison, about ten years old custom Mental Ray shader called T2S Illumination, had a bunch of presets for various materials, I'd believe measured, all of them played in all RGB channels, giving a much better (imho) description of things like gold or copper - instead of just one of many Fresnel approximations.
By the way, default diffuse - reflection mix of MIA Mental Ray material, I think it is, in SI render tree 'language': inverted incidence, plugged into scalar math exponent node (with exponent of five), change range from 0.2 to 1.

ronaldomiranda
Posts: 38
Joined: 04 Mar 2013, 13:01

Re: Custom fresnel curves in Softimage, is that possible?

Post by ronaldomiranda » 16 Jun 2015, 19:04

*

Thanks Mathaeus for your reply and time!
you are much more ahead of xsi knowlegde than me, maybe some stelar years :)

the results seens pretty convincing (on the images show in the video demo)

:)

*
Last edited by ronaldomiranda on 17 Jun 2015, 12:19, edited 1 time in total.

User avatar
Daniel Brassard
Posts: 864
Joined: 18 Mar 2010, 23:38
Location: St. Thomas, Ontario

Re: Custom fresnel curves in Softimage, is that possible?

Post by Daniel Brassard » 16 Jun 2015, 21:57

Related subject on NVidia ARC forum if you are interested.

https://forum.nvidia-arc.com/showthread ... IOR-Curves

Refractive Index database

http://refractiveindex.info/

I also attached the last zip file from JJJenkins if your are not a NVidia ARC Forum member. It's for Maya but you probably can de-construct it for Softimage

A more recent version of the script is available on CreativeCrash at:

http://www.creativecrash.com/maya/scrip ... renderblog

P.S. The RGB values are explained in part 2 of the article.

http://therenderblog.com/custom-fresnel ... ya-part-2/
You do not have the required permissions to view the files attached to this post.
$ifndef "Softimage"
set "Softimage" "true"
$endif