[HELP] Is projecting all in Zbrush same idea as baking normal maps?

laylala

Hello. I'm fairly new to both Zbrush and Maya and trying to learn the workflow between two.
here goes my dumb question... Is projecting all in Zbrush same idea as baking normal maps? 

so here is where I'm stuck :

I made a high ploy model in Zbrush and did retopo in Maya. I made a uv map of the low poly model and brought it back to zbrush.
At this point it's really confusing to proceed further. I understand the idea of transferring details from high poly model to low poly model, but why bake normal maps when you can just project all details in zbrush? Is there any difference? 

Also, I tried polypainting on both high poly model and low poly model(with uv map) just to see if there is any difference..(somehow I thought I'd see some difference because one has uv map) and it was pretty much the same. So..  does that mean if you want to paint in zbrush, you don't need to do retopo and do uv map? 

The model that I'm working on is a unicorn, it's fairly simple with only two subtools (body and eyes). It's rather stylized but also realistic looking.  

Thank you.

cryrid

They are two different concepts. In Zbrush, projecting can be a prerequisite step that might need to be done before you move on to baking the maps. 

Basically Zbrush is limited in that it won't let you bake texture maps (color, normal, displacement, etc) using two different models. It can only look at a single model/tool at a time, and so it looks at the difference between subdivision levels in order to figure out what data it is supposed to bake to the texture maps. This is why you have to 'project' the detail in Zbrush. This action takes one model (usually the new lowpoly) and shrink-wraps it to whatever else is visible (usually the sculpt). If you continue to subdivide and project enough times, you'll be left with a subtool that has the lowpoly topology and UVs at it's base level, with all the sculpted details and paint stored on higher subdivision levels (and because this single model now has subdivision levels and UVs, you'll be able to move on to actually baking the maps in zbrush). 

Personally, I'd avoid baking maps in zbrush.
Projecting is a hassle that usually creates errors of its own, and it gives you next to no options for baking the maps (no control over vertex normals or tangent basis, padding is stuck at a lower value, offset UVs might lead to bake errors, etc).  Xnormal is free and great for baking, Maya probably works just as well (though I'm not sure if it can read polypaint data?).

If you're baking with xnormal, then the highpoly model wont need UVs - only the lowpoly model needs them.  

laylala

Thank you so much Cryrid for your answer, I definitely want to look into xnormal for baking!

 I have few more questions about working in Maya. When importing object from zbrush to maya, do people usually delete the base mesh after they're done retopoloy? Whenever I click on the object it select the original object(the one that I imported) instead of the newly created retopology.

 In my outliner I have two imported objects and two polysurfaces(retopology). If I want to export them for xnormal to create a normal map, what is the best way to go about it? Should I place both uv in a 0-1 space? or do they have to have their own uv space? also if I want to place both uv in a 0-1 space, do I need to merge both polysurface1 and polysurface2? 

The two objects are horse's body and horse's mane. I'm not sure how to deal with multiple objects in maya.. it seems very different than subtool menu in Zbrush. I can't imagine how hard it will be dealing with so many objects in the future when I can't even navigate two. Sorry for my English it's a bit hard to explain.  

kanga

You haven't told us what you want as an end product. If its a low(er) poly mesh for a game engine then a low(er) poly mesh with the details of the high poly mesh is what you want. Projection in ZB is used in the sculpting process and is not necessary for making a game mesh. Its used to project the details from your original sculpt onto a new/better mesh with reorganized geometry so you can contunue working and achieve more detail. Its not always needed.

Find a tutorial on making a game character with ZB and Maya.

laylala

Thank you so much for your answer! I'll look into those tutorials! 

nellyb

cryrid said:

Basically Zbrush is limited in that it won't let you bake texture maps (color, normal, displacement, etc) using two different models. It can only look at a single model/tool at a time, and so it looks at the difference between subdivision levels in order to figure out what data it is supposed to bake to the texture maps. 

Thank you for explaining this! I spent a while searching for this answer