My V-Ray concerns -- please tell me I'm wrong.

[Vizioen]

The visual below is an example of a scene where the use of GTR was out of the question. I used GTR as BRDF on every material but I had an enormous amount of noise (noise that even didn't go away after hours of progressive rendering). Changing to Blinn/Ward cleaned the render up a lot better/faster.

There aren't any light portals here only vray disc lights to light the scene.

[vlado]

Can you get me that scene? I want to try it with the new glossy Fresnel that I'm working on...

Best regards,
Vlado

[LudvikKoutny]

Can you get me that scene? I want to try it with the new glossy Fresnel that I'm working on...

Best regards,
Vlado

Does this mean same thing as PBR standardized shading in new Corona (lower glossiness reducing reflectivity)? Because that's what I am currently missing the most in V-Ray. It makes absolutely HUGE difference in material creation process.

Aside from making material appear identical with what things like substance designer/painter output, it makes material creation process so much easier, and takes all the guesswork out of it.

As long as material is non-transparent dielectric (which vast majority of materials) is, you can simply keep reflection color 100% white, IOR around 1.5, and focus on glossiness map only, and you will get incredibly realistic materials almost every time. It is especially obvious with materials that have SSS. When using old fresnel, the materials look good from facing angles, but towards grazing angles, they all fall off into this generic hard glass-like shading, which makes most of them appear really unnatural.

I am currently in process of making some assets and doing both Corona and V-Ray version, and while in Corona I can IOR-1.5-and-100%-reflectivit-ze almost every material, with V-Ray I have to apply that old confusing rule of thumb where the rougher material gets, the lower reflectivity and higher IOR it has. So while regular glossy ceramics is IOR 1.5 and 100% reflectivity like in Corona, for example glossy furniture wood has to be IOR 1.7 and reflection around RGB160-180, and something like Concrete goes as far as IOR 2.2 and reflectivity of RGB-60-ish...

This dark magic kind of material setup feels very arbitrary, and results therefore vary a lot. That's why I think that this simple change is so big. It also makes material look a lot more realistic from various angles, where you don't feel like you need to tweak the material just a bit more once camera angle and lighting changes.

Lastly, especially when viewing large flat surfaces, surfaces with old fresnel tend to lose a LOT of reflection detail, where as glossy fresnel preserves that detail, increasing realism a lot.

Here's example of one asset I did recently:



Top one is Corona, bottom one is Vray. The point of interest here is the concrete floor. I could not use Corona PBR approach with V-Ray, because concrete would immediately light up and lose all the detail from grazing angle. Corona material is just IOR 1.5, 100% reflection and glossiness map, and V-Ray material is IOR 2.0, reflection color RGB 64, and same glossiness map.

No matter what combination of IOR, reflection color and glossiness map tweaking i tried, I could not get anything close to Corona result where I do not lose that glossiness texture structure at grazing angle.

So I am really sorry for hijacking this thread about performance, but I ma really very excited about having PBR style glossy fresnel in V-ray too

PS: It could also (at least partially) put end to those "how do I get this material looking right" kind of debates.

[vlado]

Yeah, it's the same thing... I'm afraid you'll have to redo your assets In the meantime, the alSurface material will do pretty much the same thing, so you can use that one. It will be included in the next V-Ray service pack too.

Best regards,
Vlado

[vlado]

PS: It could also (at least partially) put end to those "how do I get this material looking right" kind of debates.

Somehow I really doubt it...

Best regards,
Vlado

[LudvikKoutny]

That's awesome to hear.

I want to avoid AlSurface as its material creation philosophy just doesn't click with me. I guess I will get back to it sometimes in the future, but so far I wasn't very comfortable using it for regular materials. For SSS materials it works great though.

Redoing assets shouldn't be that hard really. I guess I can just get a script to make them all IOR 1.5, reflection colors to have max value, just filter out those that have maps plugged in reflection slot, and touch those manually. It will be definitely worth the improved results.

By the way, if you are looking for a scene to test glossy fresnel on, I've recently re-made my Esherick House scene in both V-Ray and Corona in nearly identical conditions: http://www.turbosquid.com/FullPrevie...ral=Rawalanche

I think it would be great scene to test all kinds of shading behaviors as well as do all sorts of interesting comparisons. If it would help you to get the glossy fresnel (or some other things) right, I can send you the scene.

[vlado]

Yep, the more scenes I have to play with, the better

Best regards,
Vlado

[LudvikKoutny]

It's sent

[Vizioen]

So I didn't have the GTR setup anymore but I just did a quick conversion, and the result is as expected. See below. I don't know but maybe I'm doing something wrong in terms of scene setup (lighting, exposure, color mapping). But after 20 minutes of progressive rendering and with active noise of 0.007 (30% left), it shouldn't look like this I guess. Where can I drop the scene? It's 230MB zipped.

Beauty:

Refl:

[vlado]

You can put it on wetransfer, or anywhere else like that, or you can email me to vlado@chaosgroup.com for the FTP info of our server.

Best regards,
Vlado

[Vizioen]

You can put it on wetransfer, or anywhere else like that, or you can email me to vlado@chaosgroup.com for the FTP info of our server.

Best regards,
Vlado

Ok I'm sending it to your email with wetransfer, should be there in a few minutes.

[vlado]

I got it, thanks! Will post some images with the glossy Fresnel option when it's in the builds.

Best regards,
Vlado

[BBB3]

Well I'm not quite sure but could this also be related to the BRDF you might be using? I tend to use GTR for everything nowadays but I experience A LOT more noise with this than with a blinn or ward.

I use GTX sparingly because of the noise on large surfaces and because of the white halo on grazing-angle reflections when using high glossiness.

[mitchell_architecural]

Was there ever an update to this? When Bertand speaks, I listen.

[vlado]

Was there ever an update to this? When Bertand speaks, I listen.

For the GGX, yes - like I said we are working the implementation of glossy Fresnel. For the 1.5 vs 3.4 comparisons, so far in all my tests 3.4 is a lot faster with the same settings and for similar quality - I'm still working on some good comparison images to post. If you want to know something else, please clarify.

Best regards,
Vlado