Corona 1.3 Normal Map Issues

[JJG]

Hey, recently I have been trying to render some objects with Corona that are using normal maps to make scene's more performance friendly.
I am having a bit of an issue though.

I am using xNormal to bake the normal maps.
These are my baking settings inside xNormal:



It seems to me like the normal map is incorrect when looking at the render I get from Corona.
It looks almost like the normal map is bending "inwards".

Here are some examples of the same normal map rendered in different applications, where the same normal map seems to work just fine:
Marmoset Toolbag 2
http://imgur.com/GhrNUxd.png
http://imgur.com/rcA1bs0.png
Substance Painter 2
http://imgur.com/ZzqT1IK.png
3ds Max 2014 : Corona v1.3
http://imgur.com/HHO217l

If someone could point me in the right direction as to what is going on here [...] because I don't quite get it.
Is this a bug or am I doing something wrong somewhere?

[dubcat]

90% of the time I have to "Flip Green" in Corona.
Even the Normal Maps you bake in Corona need to be flipped.

[Ludvik Koutny]

Yep, flipped green is unfortunately 3ds Max's standard of handling normal maps. Same happens with Mental Ray. But I think Corona would be better off defaulting to modern worldwide standard rather than 3ds Max's obscure one (flip green checkbox could be ON by default).

[JJG]

Well, I do not think the issue is with the bake per se.

I posted my xNormal bake settings because I wasn't baking with default +X.+Y.+Z.
I baked the whole normal map using +X, -Y, +Z; because as far as I understand this is 3ds max's coordinate system.

This is also the reason why I flipped the Y channel for marmoset since it uses +X, +Y, +Z.
But just in case, here is the render with Y flipped:
http://imgur.com/W3YfeGX

It still looks as though the normals are denting inwards.
I have also tried every possible other combination of flips inside the material, but the issue persists!
I can't get the normal map to behave the same way it does in Marmoset and Painter.

*Edit: http://imgur.com/q9q5s1T

[romullus]

If you took care of Y (green) channel flipping, then there should be no problems. Corona prior to 1.3 has issues with displaying normal maps on inverted surfaces, but in latest stable build it should work without issues. Could you test how your normal map works with other renderer in 3ds max (mental ray, vray or scanline) to see if there's problem with Corona or with your normal map.

[JJG]

I can try rendering in other 3ds max renderers once I get home from work.

[romullus]

Yep, flipped green is unfortunately 3ds Max's standard of handling normal maps. Same happens with Mental Ray. But I think Corona would be better off defaulting to modern worldwide standard rather than 3ds Max's obscure one (flip green checkbox could be ON by default).

I really hope that this won't happen. Corona plugin for 3ds max should follow max's standarts and not something else's. Everyone that works with max long enough, has bunch of normal maps already fitted to it's standart... well, at least i do. It would be rather annoying if there will be necessity to undo green channel flipping everytime i plug normal map.

[maru]

There could be a global "flip r/g/b" or "toggle flip r/g/b" somewhere in the UI or in converter script, but I can imagine how much havoc it could cause at the same time...

[Juraj]

But I think Corona would be better off defaulting to modern worldwide standard

Absolutely this. We'll soon have seamless interchangeability between applications, and unified shading, it's matter of few years. There will be minimum of users who use ONLY 3dsMax, and thus can't be bothered to change. Just because 3dsMax has it wrong doesn't mean others integrated plugins should follow suite to accommodate for it.

Everyone that works with max long enough, has bunch of normal maps already fitted to it's standart

There are users who works so long with 3dsMax they have bunch of maps with incorrect gamma saved. What to do with them now ? Let them work in stupid way ? Even Vray is getting rid of the "linearize" button in their UI so that everyone has to use linear workflow correctly, their old scenes be damned.

[JJG]

Alright, so here are two more renders using both Scanline Renderer and mental Ray, perhabs this will be useful.
http://imgur.com/tSSn3rf
http://imgur.com/ZddSsGn

They don't look that awesome either but they don't have that weird shadow going down the middle.

[PROH]

Hi. Might be wrong, but I think you should try removing all smoothing groups from the object, and then load the normal map with gamma override 1 instead of adding gamma in the normal map.

[JJG]

Hi. Might be wrong, but I think you should try removing all smoothing groups from the object, and then load the normal map with gamma override 1 instead of adding gamma in the normal map.

You are a genius, that's exactly it.
http://imgur.com/l0Biqax
I have also figured out why it worked in the other programs.
I exported from max with the zbrush preset active. Now even if I change the preset the change will not be saved and it will still just export the preset.
I didn't know that and I didn't see it either.

So, well.... I guess that's the end of this thread :P