Some questions about ZBrush and co

Aranoth

Hello,

Currently I use Cinema4D to make my models, BodyPaint to unwrap the textures and Photoshop to paint them.
All is fine.

However I want to try to use normal maps for per pixel lightning in my engine. But I have some questions :

1) Normal maps are just textures that represents the normal of each pixel. Tools like ZBrush (or Mudbox) allow us to sculpt the low poly models and generate a normal map for them, right ?

2) If so, should I unwrap the texture coordinates of my model before importing it to ZBrush ? I think so because I don't see how ZBrush can generate a normal map without UV coords.

3) Can ZBrush made the diffuse texture for me ? Can I just color my model in ZBrush and apply the shading of the sculpt to it ?

4) Imagine I had sculpted my model in ZBrush, but I want to apply some changes to the low poly model (ie: the anatomy was wrong ), what happen in ZBrush then ? Is it possible or should I make sure the low poly model won't change ?

5) Is there free alternatives to ZBrush ? I'm downloading xNormal right now but I'm not sure when I will be able to test it. I'm not even sure they do the same job.


Thanks for your time

Valandar

1 ) Sort of. What they do is allow you to ramp the model up to ludicrous polycounts, sculpt them, and then return that information as displacement or normal maps, among many other things.

2 ) Depends. You can either do it that way, or you can create the model entirely in ZBrush, and retopologize.

3 ) ZBrush can do something similar - you can paint the vertex colors. And when the model has 5-6 million polys, that's often right about a single pixel per vert - or less!

4 ) Depends on the change. If it's simple pushing of shapes, you can simply lower the resolution down to the base shape, move and twist and pull there, then ramp back up and get started again where you left off. If it's a fundamental change, yeah, you'd need to start over. But by using what are called subtools, you can even do things like swap out parts in ZBrush.

5 ) As things stand now, the two primary alternatives to ZBrush are Mudbox and 3D Coat. I don't know exactly how Mudbox compares to ZBrush except that it IS comparable, whereas 3D Coat is a lower end solution that while it does the same job, isn't quite as powerful as either ZB or MB.

And you're welcome!

pior

Hi Aranoth!

You seem to have a fairly good grasp on these questions already! With what V added, I think you've got everything you need. I would suggest you create a post in Pimping and Previews showing your early sculpted model (or even, a classic subdivision model made in C4D), try to bake this down to an appropriate lowpoly and ffrom there, ask whenever you hit a problem.

A few things that could help :

For your early models, don't try to go too complex in terms of workflow.Yes Zbrush can 'texture' models but the process is a whole (rather rigid) pipeline in itself with workarounds and tricks to know. I would suggest trying the following basic pipeline for now.

> Make a highpoly test model that you like, but don't spend too much time on it. Don't UV it. You don't even need to Zbrush it.

> Create a lowpoly model that matches the outline of this highpoly test model, with a polygon count that your engine reasonably supports. UV it using automatic relax tools wherever you can, but try to keep the UV islands as large as possible, with seems in hidden away (no fully automatic unwrap.) Don't try to UV map the oldschool way. (ie there is no need to unwrap the edges of the UV islands on straight lines, this would only cause troubles). Make sure that the lowpoly is triangulated before export.

>Export both hi and lo as OBJ.

>Get familiar with the Xnormaltexture baker (you don't necessarily need to play with its 3D viewer), how to load objects, how to setup bakes.
Render the tangent space normals, the objecs space normals also for test sake, the wireframe, and the AO (AO settings will need alot of experimentations to get them right)

> I would suggest you also play with the Xnormal tool that let you convert a tangant space normalmap into a 'crevice' map. This is a very handy thing to have to push the texture the extra mile and can make a great difference. Crazybump is great at generating this map too, but is not free.

> Create your starter texture in Photoshop combining : The AO map, the crevice map, and maybe even the Blue channel of your Tangent space NMap. This should get you started for your diffuse and specular maps, as it will give you a very nice non-directional shading that will greatly support your coloring.

> Color your diffuse in photoshop, or using the 3D paint techniques you are maybe already familiar with.

> Time to throw all this in your engine!!

Good luck!

Aranoth

Thanks for the replies and the tips, Valandar and Pior, I will experiment following Pior's protocol.

See you in Pimping and Previews then !