Some questions about HP - LP in Zbrush

Numbtea

Hey all, I've been playing about with Zbrush for a bit. I've decimated my model to around 1000 from 400k after finishing my sculpt. I'm just wondering how I can take that high poly information and use it on the Low poly version. I've done this 100% in Zbrush so it didn't initially have UV's. I took the LP into Maya and unwrapped it but then when I tried to create a normal using xnormal the map was poor.
I know you can normal map in Zbrush. I'm just wondering how I can tell the program to 'link' these meshes together. As the program doesn't decimate it down to lower Subdivison levels. (As usually I'd just take a LP mesh, up the subdivs then sculpt detail - but this time I've gone completely starting from a Zsphere).
Sorry if this isn't much to go on with just text. If you need me to specify anything just ask and I'll try to answer as best I can. Thanks for the help.

SuperFranky

To use your highpoly info on low poly you will need to bake a Normal Map. And that requires UVs. You will probably have to make a low res mesh either using Zremesher, external software or Zbrush's Topology brush to create new topology. It's probably not a very good idea to use Zbrush for normal baking, use Xnormal instead.

Numbtea

So with the Low poly I exported from Zbrush into Maya to UV (From that mesh that I decimated) how do I apply the 'Newly' UV'd item to Zbrush and have it normal map the High Poly to the low?

cryrid

So with the Low poly I exported from Zbrush into Maya to UV (From that mesh that I decimated)

I'd seriously recommend not using Decimation Master to create your lowpoly mesh. Its goal isn't to crunch something down in a way that pleases a game engine; you're still going to end up with a lot of uneccessary vertices and a lot of long thin triangles (which I'm under the impression are bad for preformance, and potentially bad for shading). It's probably not going to be a good result for normal mapping either if it tries to preserve certain details that should really be pure normal map information, and doesn't use any custom smoothing.

Retopologize it by hand. It won't take too long, and the result will be superior.

. I took the LP into Maya and unwrapped it but then when I tried to create a normal using xnormal the map was poor.

You might want to post some screenshots of the model, the uvs, the normal map, and what it looks like when applied to the model, and perhaps your xnormal settings. If xnormal isn't giving you a good result, ZBrush's basic normalmap tool is not going to be a magic solution.

If you insist on using zbrush for a normal map, then you're going to need to import the UV'd mesh as a new subtool, and experience the (sarcastic) joys of subdividing decimation master's triangulated mess and trying to use Tool: Subtool: Project all to transfer the detail from the hp to the lp in order to recreate subdivisions.