Any tips on how to make UV edges not look off when baking a high poly mesh onto a low poly?

Irraka · May 2018

My question is how would I go about making sure my UV's line up really well so that when I bake a HP model onto a LP model the seems don't look off. For instance trying to sculpt a crack on the HP model and it goes over a seem where the UV is. Is there a way to make sure this doesn't look off or is this a problem that needs to be cleaned up in photoshop?

CrackRockSteady · May 2018

You need to do a better job of explaining what you mean by "look off". Probably best to just post an image of the issue you're describing.

There really shouldn't be any issues with details being baked across UV seams...

Edit: It will also help if you give more information about what exactly you're doing. What are you modeling, what modeling software are you using, what software are you using to bake, what are you using to display the model (Marmoset, UE4, rendering in max/maya, etc)

Irraka · May 2018

Okay so here is an image of what my problem is. https://i.imgur.com/AXBAxhU.jpg I'm trying to bake a High poly mesh onto a low poly mesh from zbrush as you can see the edges of the UV shells look off where they should be seamless.

PolyHertz · May 2018

Are you saying you baked the normal map in zbrush? Don't do that if so, as iirc zbrush doesn't support mikkt space (the most common tangent bases used these days). Also, if you have split normals along the seam try baking with them merged (ie. one smoothing group / soft edge).

Irraka · May 2018

PolyHertz said:

Are you saying you baked the normal map in zbrush? Don't do that if so, zbrush doesn't support mikkt space (the most common tangent bases used these days). Also, if you have split normals along the seam try baking with them merged (ie. one smoothing group / soft edge).

No I didn't bake the normal map in Zbrush. I created a low poly model in maya, uvmapped it in maya, then I imported the obj into zbrush, created a high poly mesh, exported that and created the bakes in xNormal and when I bring up the low poly model in Marmoset and put the normal material on the low poly model it looks weird in some spots.

m4dcow · May 2018

It almost looks like your whole model is all hard edges/no smoothing groups, so you likely have an issue with your low poly mesh.

CrackRockSteady · May 2018

I think @m4dcow is right, I think it's a combination of how your model is smoothed and the way you baked your normal map.
It looks like your model is all hard edges/separate smoothing groups, but you've failed to break your UVs at those edges, which is giving you weird results at the corners. The areas I've circled in red on your normal map are what I'm talking about (there are more that I haven't circled obviously). Almost all edges on your model are going to get weird shading because the map isn't correctly baked.

Image: https://us.v-cdn.net/5021068/uploads/editor/td/a5kwsfceutwy.jpg

Check out this thread/document: http://polycount.com/discussion/146667/a-practical-guide-on-normal-mapping-for-games/p1

Here's also a relatively simple demonstration of the problem. Your model appears to be having the issues seen on the center cube (separate smoothing groups, connected UVs). You'll want to separate smoothing groups/split UVs.

You'll need to set up your smoothing groups and UVs in a manner that works properly for baking normal maps in order to avoid shading issues like this.

Any tips on how to make UV edges not look off when baking a high poly mesh onto a low poly?

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