Terrible shading errors with baked normal maps

Fisher007

Hi,

I have some issues using baked normal maps. Any tougher gradient gives massive shading errors, no matter what I do. The only solution is to use hard edges with UV splits at higher degrees.

Baked a simple box, left side has soft edges, right side has hard edges. 

As you can see it is perfectly fine in Marmoset. (or at least perfectly usable)

Any idea what should I do? Is it not possible to bake normal maps in Max anymore?

Thanks,
Fisher

LMP

Looks like you need a higher bit depth for the color channels. Try to bake them in a format that supports 16 bit color channels, also try turning on dithering, that should also reduce the artifacts.

Fisher007

As far as I know UE4 only uses 8bit only and Max makes dithered normal maps automatically.

JedTheKrampus

That's a tangent space sync problem. If you triangulate, make a cage, and then bake in xNormal with the checkbox checked in the MikkTSpace options, Substance Designer, Knald, Blender, or Mightybake and optionally flip the green channel if it needs to be flipped it will work fine. Or, you can export the tangents with your lowpoly from Max to xNormal and it will use those for the tangent space. If you do that you will need to import those tangents in the the UE4 import options as well for it to look right.

Fisher007

Hi Jed,

Yes, I managed to get good results with xnormal, although the main problem is that I don't really want to leave the modeling software. It's probably me, but baking more complex forms usually ends up with quite a back and forth. Exporting then importing to xnormal doesn't really make it faster.  So the big question for me if it is possible to bake in Max for UE4.

Thanks!
Fisher

JedTheKrampus

You should be able to bake a world space/object space normal map in Max and convert it to tangent space with xNormal (look in the Tools tab) and have it work correctly. That would mean that you don't have to fiddle with the cage etc. in xNormal. I'm not a veteran Max user so I'm not totally sure about this but I think it should work. I've used it enough to know that the tangent space normal maps it gives you are not quite correct for the tangent basis it exports.

Fisher007

I tried that as well, no luck so far unfortunately. 

JedTheKrampus

You need to swap the blue and green channels of the object space normal map baked in Max for it to work correctly.