Banding artifacts on 16 Bit normal map only in UE

Sani

Hi, I've almost finished working on my game-ready model, and now I'm trying to set up a normal map for it. However, when I assign the normal map to the model, I encounter some nasty banding artifacts. This issue occurs only in UE (I also tested it in Marmoset Toolbag, Blender, and Substance Painter). I use a 16-bit normal map, and I've tried enabling "Use Full Precision UVs" in the static mesh editor, setting the GBuffer format in project settings to high-precision normals. I am using Normalmap compression in my texture settings, with sRGB turned off. Virtual texture streaming is turned on (because I also use UDIM textures), and the sampler type in the material editor is set to virtual normal. I would be very grateful for any help in solving this problem!

rexo12

I wonder if BC5 (Unreals NormalMap compression format) doesn't support 16 bits per channel. I can't find a definitive answer, but that is what Microsoft's DirectX docs suggest at least.

poopipe

Bc5 is two bc4 stuck together so it's 8bit 

Best practice is to not have massive wide gradients in your normal maps

An alternative would be to use bc6h or whatever unreal calls it but that's very expensive