As I was doing test on the skin shader for the fresnel reflection, I discovered that it’s impossible in the Vray mtl to get nice fesnel effect, like it should be.
I tried in Mental ray with the architectural mtl and design to do a fresnel effect, and it’s quite simple and easy, I just played with the curve and I get a nice effect. I tried to reproduce this effect in Vray but was unable, and also notice where the light hit the surface and generate a high light how much better the one in mr look.
I tried to join an image but it do not work.. I don’t know why..
I think something like a vray fresnel map or something like that that you can add and have lots of control would be really cool addition! Or something into the Mtl already integrate like in the arch and design
Exactly…
Use a falloff map and set it to fresel. Problem solved
But I do remember Vlado saying the SSS2’s reflection was different from the standard vray material…hmmm maybe I’m wrong here, I’ll try and find the thread.
Yes your wrong. Thats what i do using à fallof iu do not get the same result as in Mr and in the sss2, there is just something not working well in the reflection right now. Cant wait to have an option to get it right.
Would it be possible to show some examples (screen-shots /scenes) between MR and Vray and explain us what is not possible to be created with Vray ?
Thank you very much in advance.
Yep - could you pop out some render buffers of the affect you’d like to see from mental ray? Maybe a black object with one or two area lights from the side so we can see exactly what the reflections look like?
For what it’s worth, I reckon the mental ray glass in that book is wrong, the spec highlight is changing but the actual environment reflection is not being affected in the same way.
Here’s an exemple, ( i tried to upload it , it was not working had to do it with the basic uploader version..) so you see, the one top left is the one in mr, you noticed a nice fresnel edge effect, all the other are Vray test, I tried with fallof custom curve, with the vray mtl fresnel checked and with the arch and design .. and I could not get the same result.. I have the same problem for my skin shader trying to do a custom fresnel, the one in the sss2 shader seems to wrok well but is not exposed and cannot be used in any other mtl on tweaked etc. So I would like it to be exposed, I kn ow vlado told me it should be exposed soon, hope it’s not just exposed in the sss2 shader but also as a map fresnel or something so we can use it in other mtl, like the vray mtl, etc.
Hmm - what is the MR one reflecting? It’s got a nice fresnel edge alright but is it reflecting brighter than the environment it’s seeing? As in is it breaking energy laws for the sake of looking nice? Is it the white rim at the edge that you’re liking in the mr render?
joconnell is right, there is nothing in the scene (nothing that is visible from that angle, at any rate) to cause the bright edge in the mr rendering if the shader is physically accurate. Can you post that scene?
I guess it’s reflecting the plane, wich is grey. I do not have the scene, but I just rebuilted it now, and I put the plane pink and the environnement white, work well to me.. Yes I like the fresnel effect around, I cannot get it right in Vray, it’s like if it’s never as sharp and there is energy loss at some angle compared to mr. That’s also why I was not able to match the fresnel of the sss2. BTW the fresnel effect was strong because I putted it to the roof, just for show cas.. you can lower if you want, you will see in the exemple and in the scene that I will post.
I cannot link the files or images from work, so I’ll do it when I’m home, in about 1h.
You can get the same effect with a Vray Blend Material. Create a VrayBlendMaterial. In the Base material slot you put a VrayMaterial with your intended diffuse color.
In the first Coat Materials slot also put a Vray material with a black diffuse, reflections and fresnel as desired. Activate the “Additive shellac mode” and turn the blend amount color
to white.
Yeah I already know all that stuff Samuel for years now… the point is that I can’t get an accurate fresnel effect in Vray, Vlado is supposed to exposed the fresnel in the sss2 so it should be good after since the fresnel in the sss2 look quite good, but we need to be able to adjust it, like the glossiness,etc and be able to add maps to control the effect better.
I think the issue is that the fresnel in vray IS accurate, but that’s the problem - you want to get a technically inaccurate result, but one that looks right to you! In your video you were boosting the specular up quite high using the rgb level of one of the maps in your shader which in theory breaks the accuracy of the material but it’s giving you a result you want. There have been a few other times when vlado’s been asked to put in features in materials that might break them on the physics side, but they’re very handy for artists to have that little bit more control.
with the sss2 it’s easy to get this, look , do a simple test yourself, put the sss2 with the fresnel on , on one of your head character, and try to match it exactly with a blend mtl, good luck. ^^ Anyway Vlado know about it and he will expose it in Vray 3, I hope it gonna be a map or something that we can use in the vray mtl also, not just a part in the skin shader.
Hmm - with those pictures though I’d say you’d probably have very powerful lights quite far away, so the diffuse lighting is normal due to the falloff distance, but your spec and reflection is really high since the distance from a light affects it’s intensity less?
Terminology getting mixed up here?
I’m guessing you mean most of the reflection is coming from the ground?
As for your examples, maybe using something CG would be better, as most people here won’t be bothered recreating those fighting images just to try to make the regular vray reflection match what SSS2 has.
Make a scene and post it, and we can fiddle and tweak to see how close we get.
http://books.google.ca/books?id=feVF3\_TZO9cC&pg=PA379&lpg=PA379&dq=3dsmax+edge+fresnel&source=bl&ots=ulIoZxMmI2&sig=imGDsh9dkZc-zFq1AcBvOFDFVE0&hl=en&sa=X&ei=XQ6FUoajNpOMyAGC4YH4Dw&ved=0CEgQ6AEwBA#v=onepage&q=3dsmax%20edge%20fresnel&f=false
