Understanding Flipped UVs and Normal Map Channels
polycounter lvl 15
Hey, quick question. I want to see if I have this right. Regarding inverted Normal maps showing up on one half of your model when you've have uvs overlapping with mirrored geometry.
The error arrives from flipped UVs with tangent space normal maps is dependant on which axis you've mirrored your object in. So since for characters, you generally mirror along the X or Z, so your Green channel would be consistent since it contends with vertical shading. This would require your Red channel to be flipped either manually or in engine. Same for something like a pillar you mirrored vertically, your red channel would be consistent while your green channel has now been inverted.
Feel free to correct my wording if I'm off base, trying to dig a bit deeper on the subject. Thanks ahead of time!
The error arrives from flipped UVs with tangent space normal maps is dependant on which axis you've mirrored your object in. So since for characters, you generally mirror along the X or Z, so your Green channel would be consistent since it contends with vertical shading. This would require your Red channel to be flipped either manually or in engine. Same for something like a pillar you mirrored vertically, your red channel would be consistent while your green channel has now been inverted.
Feel free to correct my wording if I'm off base, trying to dig a bit deeper on the subject. Thanks ahead of time!
Replies
Which error is that ?
Are you talking about mirrored UVs on stacked/offset islands?
you should only need to flip channels if bake and render are opengl and directx(or vice versa)y-/y+ I've never had to flip the red channel.