ZBrush FAQs


ZBrush 4 Sculpting for Games: Beginner's Guide

ZBrush 4 Sculpting for Games: Beginner's Guide

Sculpt machines, environments, and creatures for your game development projects

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Q: Why do we use ZBrush and why is it so widely used in the game and film industry?
A: ZBrush is very good for creating highly detailed models in a very short time. This may sound trivial, but it is very sought-after and if you have seen the amazing detail on some creatures in Avatar (film), The Lord of the Rings (film) or Gears of War (game), you'll know how much this adds to the experience. Without the possibilities of ZBrush, we weren't able to achieve such an incredible level of detail that looks almost real, like this detailed close-up of an arm:

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But apart from creating hyper-realistic models in games or films, ZBrush also focuses on making model creation easier and more lifelike. For these reasons, it essentially tries to mimic working with real clay, which is easy to understand. So it's all about adding and removing digital clay, which is quite a fun and intuitive way of creating 3D-models.

Q: Where can one get more information on ZBrush?
A: Now that you're digging into ZBrush, these websites are worth a visit:
http://www.pixologic.com. As the developers of ZBrush, this site features many customer stories, tutorials, and most interestingly the turntable gallery, where you can rotate freely around ZBrush models from others.
http://www.ZBrushcentral.com. The main forum with answers for all ZBrush-related questions and a nice "top-row-gallery".
http://www.ZBrush.info. This is a wiki, hosted by pixologic, containing the online documentation for ZBrush.

Q: What are the most important hotkeys in ZBrush?
A: The following are some of the most important hotkeys in ZBrush:

  • To Rotate your model, left-click anywhere on an unoccupied area of the canvas and drag the mouse.
  • To Move your model, hold Alt while left-clicking anywhere on an unoccupied area of the canvas and drag the mouse.
  • To Scale your model, Press Alt while left-clicking anywhere on an unoccupied area of the canvas, which is moving.
  • Now release the Alt key while keeping the mouse button pressed and drag.

Q: What is the difference between 2D, 2.5D, and 3D images in ZBrush?
A: 2D digital Images are a flat representation of color, consisting of pixels. Each pixel holds color information. Opposed to that, 3D models—as the name says—can hold 3-dimensional information. A 2.5D image stores the color information like an image, but additionally knows how far away the pixels in the image are from the viewer and in which direction they are pointing. With this information you can, for example, change the lighting in your 2.5D image, without having to repaint it, which can be a real time-saver.
To make this even clearer, the next list shows some of the actions we can perform, depending if we're working in 2D, 2.5D, or 3D:

  • 3D – Rotation, deformation, lighting,
  • 2.5D – Deformation, lighting, pixel-based effects
  • 2D – Pixel-based effects

A pixel-based effect, for example, could be the contrast brush or the glow brush, which can't be applied to a 3D-model.

Q: How can we switch between 2.5D and 3D mode?
A: We can switch between 2.5D and 3D mode by using the Edit button.

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Q: What are ZSpheres?
A: ZSpheres is a technique, unique to ZBrush, which allows us to create a model from scratch directly inside ZBrush. You'll see that this is a very fast way to rough out a model. As ZSpheres have a round shape, this technique is especially useful for organic forms, like a tree or a character, but less useful for modeling more straight forms like a building.
Working with ZSpheres mainly relies on four functions: Draw, Move, Scale, and Rotate. We can convert ZSpheres into a polygonal mesh using the Adaptive Skinning method. There are two modes of adaptive skinning—the newer one, and the classical skinning. Preview the mesh with classical skinning unclicked and then with classical skinning clicked, to determine which algorithm gives you better results. If both are the same, then ZBrush fails to skin your ZSpheres with the newer method and uses classical skinning as a fallback.

Q: What is Polypainting?
A: Polypainting lets us apply color onto our model on a per vertex basis. This is also commonly referred to as vertex colors in other 3D programs or game engines.
When using Polypaint, each vertex holds color and material information we can paint. This means the amount of detail we can paint depends on the amount of vertices we have.
For example, in a texture map, each pixel holds color information similar to each vertex we can paint. A typical game texture size would be 1024 x 1024 pixels, which is around one million pixels in total. So if we want to cover the same amount of detail as a 1024 x 1024 texture, we would need at least one million vertices. This is the reason why we always polypaint at the highest level of subdivision where we have the maximum amount of vertices available.

Q: What does masking do?
A: Masking protects parts of the mesh from actions such as sculpting or painting. Although it looks like masking darkens parts of the mesh, the colors aren't changed. It is just for visualization.

Q: What can we do to fix symmetry errors on a mesh?
A: There are chances of things going wrong when n the middle of finishing a complete model. For example, we may accidentally have pressed the X-key and deactivated symmetry. We didn't take notice of it and continued working, but all of a sudden, we rotate the model and see that our work hasn't been mirrored over to the other side. No need to panic, a feature called SmartReSym, located in the Deformations subpalette will help us out here.
As shown in the next screenshot, we can easily mask good-looking areas that we want to preserve and simply leave the area, to be corrected, unmasked. After determining which axis we want to mirror on, it just takes us one click of a button to mirror the details over.

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We don't even have to mask one half; we can also mask everything except for one air outlet and have it mirrored from the other side. After mirroring, make sure you check the mesh where the borders of the masking have been, there may be some little distortions that need some touchup.

Q: What are Textures and how are they used in Games?
A: Textures are images applied to 3D objects. In games, most of the texture sizes are a "power of two", so typical sizes are 256 x 256, 512 x 512, or 1024 x 1024 pixels.
In modern games, there are several types of textures that affect the look of the model in the engine. The idea behind having that many textures in games is, like always, the need for saving performance. The following three are the most commonly used types:

  • Color/diffuse maps are the most basic textures determining the base color of the object, most of the time ignoring any lighting direction.
  • Normal maps are used to simulate high polygon details on a low polygon model by dynamically simulating light and shadow on the surface. You've probably seen them before because they can easily be spotted by the dominance of purple colors. Most of the time, normal maps are generated by software, opposed to handmade color and specular maps.
  • Specular maps define the amount of specularity of the surface, where white means shiny and black means dull. Color in a specular map will tint the highlights.

However, this list isn't complete at all. There are many more types of textures but these are the most common ones used in games.

Q: How can we access the settings for the clipping and masking brushes?
A: We can access the settings for the clipping brushes by holding down their respective hotkeys while changing the settings. (Ctrl for the masking brushes and Ctrl + Shift for the clipping brushes)


This article attempted to answer a few frequently answered questions on ZBrush.

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ZBrush 4 Sculpting for Games: Beginner's Guide

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