ZBrushCentral

Zbrush is driving me nuts!

ZBrush Usage Questions
#1

I’ve been using zbrush to work on my demo reel for the past month or so, and even though I’m loving the results I get out of it, I’ve been pulling my hair off at the same time… It feels like zbrush is full of little quirks and bugs related to navigation… Here’s what I’ve come across, hopefully there will be solutions to some of these, so that I can enjoy the zbrush experience!

My computer is a 2.8ghz c2duo with 4gigs of ram.

  1. Canvas size: I’m working on a 24" screen, zbrush makes me feel like I need a 15", because scaling the canvas slows down navigation so much… that is really stupid, why do I have to compromise canvas size for speed?

  2. Zoom range: Often I will run into situations where I can’t zoom any further, the object just won’t grow any larger, this is in local mode in which I work most of the time.

  3. Object shooting back: I’ve seen this reported already but I’m still gonna mention it: when working with zspheres, the object will sometimes shoot back, either to the very corner of the canvas, or just a short amount, which is equally annoying. I press ‘a’ twice, reframe it, try to redo what I was attempting (move/scale) and there it goes again. This can sometimes happen 3-4 times in a row.

  4. I’ve been having this glitch where the object will randomly flip upside down for a second, when rotating it. I attached a file showing this happen with the default soldier model. It’s really annoying :p.

  5. Perspective: it doesn’t seem to work with zspheres! so if I have a tool with both zspheres and polymesh3Ds, say a zsphere root running up a stone, when I toggle the adaptive skin on and off, with perspective on, the zspheres will appear to shift compared to the stone, because perspective is only affecting the meshes! So I’m stuck with the reverse perspective which is zbrush’s default (yea, objects grow bigger, the further away).

  6. Slow. With shadows on, zbrush is slow, navigation is not snappy, and this is with the default canvas size which is tiny on my 24" screen. I’ve seen it be pretty fast when I don’t have zpsheres though, but the scene I’m working on right now has over a hundred zspheres, still it’s only around 50k polys. I can usually crank it to around 10 million before it’s unuseable.

It would be awsome if I found solutions to some of these problems, and maybe others will be fixed by 3.5, cause I want to like zbrush, and I don’t want to have to switch to mudbox to get a better experience.

Thanks

A-

Attachments

zbrush_glitch.zip (34.1 KB)

#2
  1. Canvas size: I’m working on a 24" screen, zbrush makes me feel like I need a 15", because scaling the canvas slows down navigation so much… that is really stupid, why do I have to compromise canvas size for speed?

You’ve never said what your display resolution is. Also, if you zoom the canvas, that is a rendering operation ON TOP OF the real-time rendering. In other words, let’s say you zoom the canvas to 200%, then you’re rendering the document while you work and also real-time resizing it to double size. That can be pretty taxing. Especially at high resolutions with large canvas.

  1. Zoom range: Often I will run into situations where I can’t zoom any further, the object just won’t grow any larger, this is in local mode in which I work most of the time.

ZBrush isn’t an infinite universe. The canvas has a big buffer around it, but you’re not going to be able to scale something so far that it will go outside the available area.

  1. Object shooting back: I’ve seen this reported already but I’m still gonna mention it: when working with zspheres, the object will sometimes shoot back, either to the very corner of the canvas, or just a short amount, which is equally annoying. I press ‘a’ twice, reframe it, try to redo what I was attempting (move/scale) and there it goes again. This can sometimes happen 3-4 times in a row.

Known issue. Nothing more to be said about it at this time.

  1. I’ve been having this glitch where the object will randomly flip upside down for a second, when rotating it. I attached a file showing this happen with the default soldier model. It’s really annoying :p.

Sounds like you’re describing gimbal lock. Suffice it to say that this is a VERY complex issue. Each version of ZBrush has done a better job of getting around the mathematics involved with the phenomenon, but obviously it’s still not perfect. You can read more about gimbal lock through a google search if you’re really feeling masochistic one day.

  1. Perspective: it doesn’t seem to work with zspheres! so if I have a tool with both zspheres and polymesh3Ds, say a zsphere root running up a stone, when I toggle the adaptive skin on and off, with perspective on, the zspheres will appear to shift compared to the stone, because perspective is only affecting the meshes! So I’m stuck with the reverse perspective which is zbrush’s default (yea, objects grow bigger, the further away).

As I understand things, real-time perspective is basically a form of deformation that’s being applied to a model’s polygons as it’s drawn on the screen. ZSpheres don’t have polygons, while the preview mesh does.

  1. Slow. With shadows on, zbrush is slow, navigation is not snappy, and this is with the default canvas size which is tiny on my 24" screen. I’ve seen it be pretty fast when I don’t have zpsheres though, but the scene I’m working on right now has over a hundred zspheres, still it’s only around 50k polys. I can usually crank it to around 10 million before it’s unuseable.

Again, what’s your display resolution? I will tell you that rendering performance is handled by your CPU. The larger the canvas size and the greater the display resolution the harder your CPU has to work to be able to render in real-time. If you’re hitting the wall of what your CPU can do, you could try a lower display resolution. Or it may be time to invest in that quad core you’ve always wanted.

#3

On the zoom or scale object limit. I have that problem all the time with say a full body were you can’t zoom close enough to say the head. The main solution for that is hiding everything but the head, then scale works as if the only only object in the canvas, so the limits change.

Are you chaging the document size to max out space on your 24inch? Which I assume you are running the monitor 1920*1200. I’d imagine that could get slow if the doc size is near that compared to default. I often leave it at default on my 20inch, where it as some buffer around the tools and menus. Using document zoom just a tad never seems to slow it down, only more pixelated.

Have you tried a doc res size that works well with your machine, then use zoom to fill the rest of the screen? With sculpting, I don’t bother with higher rez docs unless for rendering or texturing with projection master. Most everyhting in Zbrush is at default when it comes to quality.

Oh, and using ZAppLink has a saved view option, which you export for later, and is great for recovering that exact angle of your tool if you want to reload it into a higher rez doc for rendering and such.

#4

Thanks for your replies, I am indeed working at 1920x1200. I’ll try hiding the parts of the mesh, that might help.

From what aurick is saying, it seems like most of these problems I’m having are due to the fact zbrush is not a 3D app, and are ‘normal’… no true perspective, max zoom range, canvas size affects performance, gimbal locking from having to rotate the object instead of camera…
I’m starting to wonder… what’s the advantage of it being 2.5D? It seems like it brings nothing but workflow problems.

The performance is not that bad actually with polymeshes, it’s especially slow with zspheres, when you have hundreds of them.

A

#5

There are very good reasons for 2.5D, and it’s ZBrush’s 2.5D nature that makes some of ZBrush’s more famous features possible.

If you’re doing an illustration in ZBrush, you can snapshot your models to the canvas as pixols. They then become digital paint rather than polygons. This means that objects become a part of the scene in ways that you don’t get with a 3D app, and can be blended into it in ways that would require heavy postrender work with a 3D workflow. From the very start, ZBrush was designed for illustrators.

For people who are only using ZBrush’s 3D features, there are still ways that 2.5D helps:


  • You can use Projection Master to convert to pixols, then paint 3D details onto the model using all of ZBrush’s 2.5D tools – including other 3D objects. Then Projection Master can pick the model up again and deform the mesh to match what you just painted.
  • ZAppLink can be used to send your model to Photoshop, where you can use that app’s filters, text, and other features to in effect paint directly on your model. In short, you can do Photoshop stuff without needing to work on an unwrapped model and compensate for seams or texture distortions. Photoshop becomes a ZBrush plugin, and you can paint what you want to see.
  • Key is the fact that a 3D app must track every element of your scene at all times and from all angles, even if those elements aren’t currently visible to the camera. That’s a lot of system resources being reserved for scene management. Because ZBrush isn’t a full 3D app but rather a hybrid, it can focus all of those resources instead on a single model. This is one of the reasons why ZBrush can handle millions of polygons in real-time, or even a billion HD polygons.
In short, your question can be turned on its head. Especially for illustrators. “What’s the advantage of using an animation package? It seems to require lots of workarounds (like normal maps and displacement maps) in order to get any serious detail or realism.” :wink: