ZBrushCentral

A few simple questions

ZBrush Usage Questions
#1

Hi, I’m new to the zbrush, yet it’s the first 3D program that I’m using, it’s been only a few days since I started, and there are a few questions that I need to ask, because I can’t seem to find the answer by myself so far. I will really appreciate whoever helps me, and I’m sorry if these has been asked before or explained, I checked around a bit but I couldn’t find the answers to my questions.

First is, can I duplicate a subtool and make it mirror image (?) of the original, for example I made an earring and put it to the left ear as subtool but I want to put another one to the right ear and I want it at the exact same location like the left ear. Is there a shortcut or something like that for it or do I have to append, move and rotate it all over again?

Second is, about the geometry, how can I lower the poly number, I mean when I started with a polysphere to make a face I could lower the poly number till 384 polys from the geometry window and I did higher the amount by ctrl+d till 393216 polys.
To make a hair I appended another polysphere as a subtool but I couldn’t lower the poly number like the first polysphere, the lowest I got was 24576 polys. There is no problem with getting higher values but I can’t seem to lower the poly number.

My third question is how many polys should I use if I don’t want my texture to look weird on the model.

And my last question is, this can be a bit ridiculous, but I didn’t quite understand the function of saving the document, so could you explain me for what use it’s for?

#2

alright…lets go backwards.

A document is like a photoshop/flat image. A ztool is a 3d model. If you want to save the document (most people never do), then you’re been working in 2.5d for some reason (illustration, sketching, etc). If you’re working on a 3d model you always want to save the ztool or .ztl.

The number of polys you want for a texture depends on the size of texture that you’re exporting as well as the amount of UV space applied to that object. Polypainting is vertex coloring. So 1 vertex = 1 pixel on a map. So if you’re using 100% of your UV space (most people get around 85%-90%) and you want a 1k texture then you need to have at least 1million polygons (1024x1024=1,048,576). So basically, if I have an entire character taking up 1 UV map that is 2k. And I have 90% of my UV space used and all of my UV maps have the same size relation then I will need to have

2048 x 2048 = 4,194,304
so
4,194,304 x .10 = 419,430.4
so
4,194,304 - 419,430.4 = 3,774,873.6

Anyway, a lot of math that most people don’t bother with. But in order to get exactly what I have in Zbrush as polypaint onto my model in another program all of my tools would need to come to 3,774,873.6. Most of the time you will go well over that and you let Zbrush figure out the mipmapping when it calculates the textures for you. There is a lot more that factors into that when you start having subtools to build your geometry and then you’re baking back down onto a proxy mesh, but we’ll leave that for another time.

To lower your polycount you need to “reconstruct” the lower subD’s.
tool>texture>enable UV (if turned off)
tool>geometry>reconstruct subD …or something to that end

To mirror is a 1 button click with Subtool Master (free plugin on pixologic’s site).

To do it in the standard UI you have to…
clone the object
append the subtool
delete lower subD’s
tool>deformation>mirror

Then reconstuct the subD’s back

Hope all this helps