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General => Terragen Discussion => Topic started by: Cyber-Angel on August 02, 2008, 12:09:47 AM

Title: Index of Refraction Value for Wet Rock (Was Index of Refelction)
Post by: Cyber-Angel on August 02, 2008, 12:09:47 AM
Dose any one know the real world Index of Refraction Value for wet rock as it would be useful to know so I can finish this WIP I'm working on a present?

Regards to you.

Cyber-Angel  ;D

Title: Re: Index of Refelction Value for Wet Rock (Reflection Shader)
Post by: sjefen on August 02, 2008, 10:07:55 AM
I don't know, but since it is water that causes it to look wet I would guess 1.33
Title: Re: Index of Refelction Value for Wet Rock (Reflection Shader)
Post by: Tangled-Universe on August 02, 2008, 01:03:25 PM
Maybe here ;D

http://forum.cinema4d.be/vb/showthread.php?t=1274 (http://forum.cinema4d.be/vb/showthread.php?t=1274)

Martin
Title: Re: Index of Refelction Value for Wet Rock (Reflection Shader)
Post by: cyphyr on August 02, 2008, 01:15:07 PM
There is no such thing as a reflective index. Reflective surfaces may or may not refract depending on if they are transparent or not. However the water which is on the rock will have a small refractive component which will be about 1.33 with a slight variation depending on if there is salt etc dissolved in it and its temperature but these are so small as to have little visible effect.
Richard
Title: Re: Index of Refelction Value for Wet Rock (Reflection Shader)
Post by: Virex on August 02, 2008, 05:54:12 PM
Quote from: Cyber-Angel on August 02, 2008, 12:09:47 AM
Dose any one know the real world Index of Reflection Value for wet rock as it would be useful to know so I can finish this WIP I'm working on a present?

Regards to you.

Cyber-Angel  ;D

Index of reflection? You mean the percentage of light that's being reflected? I don't have a clue, but a wild guess would be around 40%.
Title: Re: Index of Refelction Value for Wet Rock (Reflection Shader)
Post by: Cyber-Angel on August 02, 2008, 07:43:31 PM
Sorry Guy's Typo on my part, that should be "Index of Refraction" sorry for the confusion?  :-[

Regards to you.

Cyber-Angel
Title: Re: Index of Refraction Value for Wet Rock (Was Index of Refelction)
Post by: krecacy on August 05, 2008, 03:23:24 PM
Hi, there's no such thinkg like index of refraction for a wet rock - since it has to be refractive - that means at least a bit transparent. Since the rock is fully opaque u dont need an index of refraction (at least not a specific one - u might use 1.333 if you have to). What you are after is a nice reflection, not refraction. I am not an advanced TG user, but u might take advantage of fresnel reflection - which is true for almost all things around us.

Cheers
Title: Re: Index of Refraction Value for Wet Rock (Was Index of Refelction)
Post by: Christopher on August 05, 2008, 04:15:57 PM
A wet rock is both reflective and refractive. Just about everything in nature has an index of refraction to some extent.

Say the rock is mostly made up of Iron which has an index of 1.51. There is a slight transparency there even though it's on a micro scale. Steel has an index of 2.5 for example. Fresnel is very helpful.
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