Normal map seams in World Space?

damageINC

Hi all,

I've been running into this a lot lately and really have no idea why it's occurring but perhaps someone here has some exp with this. To make a long story short, I've been baking tangent space normal maps out of both max and/or Xnormal and when I inspect the maps they look peachy. However, when I preview them on the model in the pre_PBR version of Marmoset, I get odd smoothing issues in areas completely away from UV seams (under the nose and at the top of the lips for reference).

On further inspection, it appears that these artifacts are the result of something in world space normals as previewed by Marmoset. I want to know how this is possible and what I can do to get rid of them. I didn't bake it as a WS normal map so I'm not sure if I'm doing something wrong process wise. Thanks.

D4V1DC

a seam, disconnected verts, bad smoothing groups or overlapping faces probably can create this.

In TBag

lmao

/ Marmo there is a setting to use 3dsmax tangent space try that?

damageINC

Thanks for the help D4V1DC........I tried most of this to no avail. And as usual, it's the one obvious thing that you never consider that is causing the issue. Turns out (ready for this one?) that the relaxed uv island was inverted. Don't ask me how I got it into that state....but fixing this oversight appears to have cleared up the WS normal seam issue. Hurray for small victories!

I still am curious though about why a tangent space normal map has any world space info to get screwed up.

D4V1DC

Glad you sorted it out, i totally forgot about flipped faces see i would have gone bonkers over this too.

AlecMoody

"I still am curious though about why a tangent space normal map has any world space info to get screwed up."

I am very confused by this statement. Your tangent space map doesn't have any world space info in it- no tangent space map does.

EarthQuake

Before a tangent space map can be rendered on your model, the shader converts it to world space coordinates, that's what you're seeing in the world space debug mode.

stevston89

The errors you are having look more like smoothing group issues than seams. Seams always happen at you uv cuts, not in the middle of the uvs. Also try exporting as an obj with precision 12. I have had errors similar to that with hair planes.

damageINC

EarthQuake wrote: »

Before a tangent space map can be rendered on your model, the shader converts it to world space coordinates, that's what you're seeing in the world space debug mode.

Thanks Earthquake, I was wondering how that was generated. I've been doing a ton of tests to try and figure out exactly what's going on and I'm inching closer. I'm not convinced the inverted UVs were causing the issues entirely. I've found that I've gotten the best exports when toggling off Normals under the Geometry section of the obj rollout.

I then create a Object Space normal map in Xnormal and use Alec's HandPlane3D. That seems to give the best result. Although I still am getting a few seemingly simple objects where the edges of the low poly are showing in the normals (I've checked that the smoothing groups are correct and beyond resetting xforms and exporting the model I'm not sure what else I can do to clean it out). I'll update as I find more out. Thanks again for all the help.

EarthQuake

A few things:
1. Make sure all of your uvs are welded (sometimes I get randomly unwelded uvs out of Modo)
2. Make sure you don't have a hard edge/smoothing group in the area you're getting seams
3. If you have mirrored/overlapping UVs, make sure to offset the overlapping bits by 1 unit. There is a bug in 1.10 regarding overlapping uvs.
4. If using max, make sure "export mesh normals" is checked on, "smoothing groups" is not enough. Also toggle on/off the optimize settings here, some combination tends to do funky stuff.

You may want to try the free trial of Marmoset Toolbag 2 here: http://www.marmoset.co/toolbag/store as a number of uv precision and mesh normal issues have been fixed/improved in the current version.