How to create matching hig poly UV with low poly UV for normal mapping

[Matteo_Corona]

Hello guys! :)

I write here hoping to solve an issue that is boring me from a while.

I had a detailed hard surface model created with zbrush.
It’s a mesh composed by various polygroups and hard edges.

Now I would like to use this hig poly mesh and project it’s details on a normal map and then use the obtained normal map to transform a low poly moldel into the detailed brother.

the hig poly I want to use is this : (3 polygroups: border, outer side and inner side).

Nothing new until now.

The issue that I can’t solve regards about what I need to do in order to have the two UVmaps (the low poly UVmap and the hig poly UVmap) matching each other shape because, if the shape of the two uv maps are different, I can’t fit the details on the low poly mesh.

I am getting mad triyng to solve this issue but still I haven’t get the solution, I don’t know this point of the overall workflow and I am not sure if I am on the goodway to get the result I want too.

Some suggestions, please?

ps:I could zremesh

Best regards and thanks for the attention

Matteo

Attachments

[beta_channel]

Your highpoly object doesn’t need UVs, at all.
I’m at little lost as to what it is you’re trying to achieve.

[Matteo_Corona]

Your highpoly object doesn’t need UVs, at all.
I’m at little lost as to what it is you’re trying to achieve.

I would like to create normal map from an high poly model and use it on the same model but retopologized and with a less poly count.
I have to use this model into Unity 3d or into other 3dapp not only zbrush.

[Cryrid]

As was mentioned, only the final low poly mesh requires UVs for baking a normal map. The UVs aren’t used in the highpoly at all; it’s surface geometry alone (the vertices) will provide all the information required for the low poly to sample and create its own normal map, instead of creating a normal map for the highpoly and then trying to apply it to the low poly (which I suppose you could do, but ultimately it would look incorrect as the data contained in the normal map is designed specifically to work in conjunction with the tangent and vertex information of the mesh it was baked for).

If you’re using an external program to create the normal map (xnormal, maya, etc), you can just give your remeshed model a set of UVs using UV master or whatever other UVing solution you’d prefer, and just export it along with the sculpt. Import the two meshes into the baking program, make sure the highpoly and low poly targets are looking at the right meshes, and you’re good to go.

If you’re baking in zbrush, the sculpt does need UVs, but the caveat there is that the sculpt and the low poly mesh need to be the exact same mesh. You’d have to take the remeshed model, UV it however you want, add it as a subtool to your original sculpt, and then start subdividing it while using Tool:Subtool:Project All to project the detail from the sculpt to your remeshed version. Then you’d be able to create the normal map internally as it uses the difference between its subdivision levels.

Personally, I recommend baking xnormal. It’s quick, easy, supports polypaint data, you don’t have to worry about projecting geometric details cleanly, you can work with the actual smoothing groups that the ingame mesh would have (zbrush doesn’t use them), and perhaps more importantly it can be synced to use the same tangent basis as Unity for a more correct render.

[Matteo_Corona]

As was mentioned, only the final low poly mesh requires UVs for baking a normal map. The UVs aren’t used in the highpoly at all; it’s surface geometry alone (the vertices) will provide all the information required for the low poly to sample and create its own normal map, instead of creating a normal map for the highpoly and then trying to apply it to the low poly (which I suppose you could do, but ultimately it would look incorrect as the data contained in the normal map is designed specifically to work in conjunction with the tangent and vertex information of the mesh it was baked for).

If you’re using an external program to create the normal map (xnormal, maya, etc), you can just give your remeshed model a set of UVs using UV master or whatever other UVing solution you’d prefer, and just export it along with the sculpt. Import the two meshes into the baking program, make sure the highpoly and low poly targets are looking at the right meshes, and you’re good to go.

If you’re baking in zbrush, the sculpt does need UVs, but the caveat there is that the sculpt and the low poly mesh need to be the exact same mesh. You’d have to take the remeshed model, UV it however you want, add it as a subtool to your original sculpt, and then start subdividing it while using Tool:Subtool:Project All to project the detail from the sculpt to your remeshed version. Then you’d be able to create the normal map internally as it uses the difference between its subdivision levels.

Personally, I recommend baking xnormal. It’s quick, easy, supports polypaint data, you don’t have to worry about projecting geometric details cleanly, you can work with the actual smoothing groups that the ingame mesh would have (zbrush doesn’t use them), and perhaps more importantly it can be synced to use the same tangent basis as Unity for a more correct render.

thanks Cryrid, the ways u suggested me are working well!!! Thanksa lot!!! :)))))))))))))))))