Baking normal map with symmetry mesh

miqus

Hello, i know that this problem is really popular here, but since i didn't fixed my mesh i decided to show you sample mesh.

I tried this: http://polycount.com/discussion/60615/symmetry-normal-map-issues

But everytime I check my normal map in MT2 or UE4, it looks like this. Seam is really small, and barely visible, but still annoying.

Here is few workflows i tried to do, but I can't do it well (i using xnormal):

1. Exported half LP mesh -> exported cage | not fixed

2. Exported half LP mesh -> mirrored mesh moved -1 on UV -> exported cage | not fixed

3. Exported full LP mesh -> not welded -> exported cage | not fixed

4. Exported full LP mesh -> welded -> exported cage | not fixed

5. Exported full LP mesh -> welded -> mirrored mesh moved -1 on UV -> sharp edges in center of symmetry mesh (Blender) -> exported cage | not fixed

@edit Also, without normal map, seam is still visible. Why?

http://i.imgur.com/UOYVXKl.jpg

Steppenwolf

First thing i would try is to flip green channel on the normal map.
Have you tried baking only half the mesh, then use symmetry afterwards before you get the mesh into game (without welding the parts)?
Seeing as you have some issues even without normal map this could be related to vertex normals (try resetting them) or lightmap uvs.

miqus

Steppenwolf said:

First thing i would try is to flip green channel on the normal map.
Have you tried baking only half the mesh, then use symmetry afterwards before you get the mesh into game (without welding the parts)?
Seeing as you have some issues even without normal map this could be related to vertex normals (try resetting them) or lightmap uvs.

Thanks for comment

I spent more time on this topic and I manage to find solution. This is simple mesh, but i think it will work in more complicated meshes. As you said, I believe that it could be problem with vertex normals.
Here are my steps:

1. I have created low poly mesh, half was deleted, after that I made UV and then symmetry.
2. I made two materials so I can see which is mirrored and which is base mesh.
3. After that I triangulated mesh.
4. I made a copy and I placed on different layer, which will be my main mesh (exported to engine).
5. I came back to my base one, I picked mirrored part and I scaled down placing in empty space on UV. This will be my low poly for baking.
6. Then I duplicate again for cage, and then pushed geometry
7. I made bake using those meshes and I checked my normal map on my mesh which was copied in 4.
This is how it's looks like (with normal map and without normal map):

I think that I made mistake before, because I triangualted mesh before I made symmetry part, that's why seam was visible even without normal map.

musashidan

You shouldn't have to go through all that hacking. Here's a quick vid tut I did a while ago. It's for Max but the very same steps apply to any 3D package:
https://www.youtube.com/watch?v=nDYLzxs7iQg

miqus

musashidan said:

You shouldn't have to go through all that hacking. Here's a quick vid tut I did a while ago. It's for Max but the very same steps apply to any 3D package:
https://www.youtube.com/watch?v=nDYLzxs7iQg

Thanks for comment but I hope that you know, that not every part of mesh element can be so easily flipped in UV map like on this tutorial - there are boxes, and circles, what about more complex mesh? Also, this guy didn't triangulated mesh before baking, which can case problems in engine.

musashidan

miqus said:

Thanks for comment but I hope that you know, that not every part of mesh element can be so easily flipped in UV map like on this tutorial - there are boxes, and circles, what about more complex mesh? Also, this guy didn't triangulated mesh before baking, which can case problems in engine.

That guy is me. For odd shells or non-symmetrical shells you can mirror the shells back across after the flip. In Max there's a mirror uvs tool that doesn't invert the shells.

miqus

Oh, I didn't know that If i had 3ds max I could try this, but since I working in Blender I need to find different solution. This one which I write few posts earlier, didn't work well and problem still exist on more complex shapes. I tried also move mirrored part -1 on UV, but it's still not fixing issue. Halp!

@edit

Ok, so here is another mesh, with small bend on top.

http://i.imgur.com/ZgIauDW.jpg

Why there is seam on mesh, even without normal map? Maybe it should look like this, but then baked normal map will look bad. I tested it many times, and everytime I have problem with mirrored baked normal map.

miqus

Anyone? I don't understand it. I tried do everything, yet problem still exist. Why this seam is visible even without normal map? That shouldn't looks like this. I fixed problem with that cube which I posted earlier, but on more complex shapes you still see some problems on conection between base and mirrored part.

A lot of people say that

1. You need move mirrored part -1 on UV

or

2. You should weld vertices

but nothing helps. I spent on this almost whole day on testing

hansolocambo

musashidan it sure is a good technic. Not as "simple" as you say it is though And when you work on a complex low poly mesh with hundreds of Texture Sets, mirroring horizontally each UV set one by one trying not to fuck up once along the way is quiet a challenge and takes time. Damn there should be an easier way

musashidan

@hansolocambo 100's of texture sets on a single asset? What on Earth are you working on?