Normal map glancing angles behavior.

[Adanmq]

Hi all. I´m trying to create a Carpaint shader using Corona and i have found a problem using normal maps to create flakes on glancing angles. I´m using Vray to compares just because it´s the only other engine i have, and i´m not sure if this is problem or just Vray being not precise enough. But i want to achieve the Vray Result because it´s more appealing to me.

I convert the material from Vray using the corona converter just to get the exact glossy values in order to get perfect match. But the real problems it´s the normal map, in Corona its visible at glancing angles causing some sort of "noise".

There is some examples:





And Corona render without Normal map. Look perfect:


All renders are RAW.

Thanks in advantage.
PD: Excuse my bad English.

[Nejc Kilar]

The way I see it just makes me want to plug the normal map into the falloff slot which is totally not a solution anyway... Weird problem ya got here :)

[juang3d]

It feels like if the vray material had a bit of anysotropy because the speculation reflection is not round, it's a bit deformed in a direction, I may be completely wrong but is what I see in the vray picture.

Cheers.

[romullus]

To me Corona result looks more legit. Could it be due to different strength of normal bump in both renderers? Can you try to increase strength in Vray or decrease it in Corona and see if you could match results?

[Ondra]

it is probably because od different ways textures are filtered in both

[maru]

Yup, looks like texture filtering to me. You can try slightly increasing blur parameter in Corona and see what happens. It could also make the result less "jaggy". Also check your normal map in Corona if it's configured properly, and if its strength is similar to what is used in Vray. See: https://coronarenderer.freshdesk.com/support/solutions/articles/5000501663

[Adanmq]

Thanks you all guys. I think i found the problem, using Corona Map (0 filtering blur) instead of 3D Studio MAX map and decreasing a little bit flakes intensity works perfect for me. And the Corona result looks better to me now. :D

Now i´m trying to improve the flakes map itself.

[maru]

don't know how you made them but I rendered some Ngons scattered over a plane some time ago and it seems to be a good direction :)

[Adanmq]

Thanks you maru!!.
I´m making mine using Substance Designer but i´m thinking on scatter some real flakes and render the normal map from MAX.

[Tanakov]

Hey, can you give more details on how you do this kind of materials?

I was looking for a neat solution as Im soon about to use "GalaxyStar" stone and would like to have that thing up my sleave.

[maru]

The birds are singing that there might be a video tutorial about this soon. ;)

[maru]

procedural flakes using cellular map, not perfect, but probably usable

[Adanmq]

Thanks Maru, look very good i will try it. Right now i make a normal map from the OSL Vray Texture but i need to render it every time and i must have UV cords, xD

Tanakov, my Shader its similar to the one from the tutorials, very simple stuff. I Share it so you can take a look. It can be optimized and maybe remove one Blend but i want to have the possibility of control the metallic/Dielectric ratio of my material, because flakes look much more integrated this way, whit out the dielectric mix the metal looks "exposed". I include 2 Flakes maps generated using the OSL Vray texture, i´m working on a better way of making them.

You need a metallic base, but the light hit this metallic surface after travel trough the paint pigment, so in order to simulate this you need to "tint" the metal reflections properly. Mix it with a Dielectric to better catch highlights and give it a better look and finally you need a clear-coat, mix it using Fresnel falloff and use a IOR of 1.47-1.6.
You control the spread of flakes using the glossy from the metallic base, the Normal bump or by using another normal map.

Here is an example:


If someone have some ideas of how to improve the shader i really will appreciate it, ;)

Download:
https://drive.google.com/file/d/0Bys9_iWhCgvfWDU0aXVDQXExNjQ/view?usp=sharing