Working with Multiple Objects

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You can work with multiple objects in ZBrush two ways:

  • Polygroups
  • SubTools

Contents

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What Are Multiple Objects?

What do we mean by multiple objects? A model in ZBrush is composed of polygon faces. A model composed of multiple objects is one that has two or more polygon objects that are not connected. That is to say, they do not share any connected polygon faces.

A practical example is the DemoSoldier that ships with ZBrush. This model is composed of many other parts such as boots, backpack, shirt, vest, ect. For the DemoSoldier they are all separate SubTools but they could also all be one SubTool and simply be separated by Polygroups. The important element here is that they are separate polygon objects. The shirt does not share any polygons with the body. The vest does not share any polygons with the shirt.

If all you need is a way to keep track of your model's various parts, we recommend that you use Polygroups. Polygroups give you a direct, visual indicator of your groups. They can be turned on and off by pressing CTRL+SHIFT and clicking on them in the viewport. They will keep you mesh as one surface so that Transpose can be used to pose all the various elements together.

  • To learn more about Polygroups click here.

If, however, you find that you need more polygons see below.

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Keeping It Separate: The Polygroup Option

If you are importing your model from another app follow the steps below to make it ready for Polygroups:

  1. In your other application, select all the parts of your model that you want to use in ZBrush.
  2. Export them all as one single OBJ.
  3. In ZBrush, import the OBJ.
  4. Press Tool: Polygroups: Auto Groups.
  5. Divide the model and start sculpting.

Now, what happens if you find that you forgot a part and need to add it in? This is easy to do but there is one variable. Do you have levels of resolution?

If you do not have levels of resolution follow the steps below:

  1. Select the Tool: Polymesh tool. This is a star shaped polygon object.
  2. Import the new part. Press Tool: Import and navigate to the part you want to add to the model. This will bring it in as a separate model for now.
  3. Re-select your original model from the Tool palette.
  4. Add the new part to the existing model. Press Tool: Geometry: InsertMesh and choose the new part from the pop-up window.

That's it! You have added a new part to your model.

If you have levels of resolution we will modify the process slightly.

  1. Select the Tool: Polymesh tool. This is a star shaped polygon object.
  2. Import the new part. Press Tool: Import and navigate to the part you want to add to the model. This will bring it in as a separate model for now.
  3. Equalize the levels of resolution. Divide the new part so that it has the same number of resolution levels as the existing mesh.
  4. Re-select your original model from the Tool palette.
  5. Add the new part to the existing model. Press Tool: Geometry: InsertMesh and choose the new part from the pop-up window.

The only step we added was to equalize the levels of resolution.

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The Polygon Count Variable

When working with multiple objects or even large, detailed creature we can begin to run into the barrier of our polygon limits. Some times our systems are just not fast enough to work with the polygon count that we want or perhaps our operating system limits the amount of RAM we can use. Either way, we may find ourselves with a need for more polygons.

ZBrush has several ways for you to adjust your workflow based on your polygon needs:

  • HD Geometry and Polygroups
  • SubTools

As of this writing, HD Geometry does not translate into displacement maps so if you need to get your sculpting detail out of ZBrush and into another application you must use the SubTool method.

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HD Geometry and Polygroups

HD Geometry allows your model to go up to 1 billion polygons. This is more polygon information than SubTools are capable of.

  • Learn more about HD Geometry here.

Use Polygroups to keep your different objects separate. Polygroups allow you to easily select, hide or show groups.

  • Learn more about Polygroups here.
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SubTools

SubTools are separate polygon objects. Each SubTool can be equal to the maximum number of polygons your system can handle. If your system handles 8 million polygons and you have 4 SubTools then your model can be composed of 32 million polygons.

SubTools are, however, separate. You can NOT sculpt or pose multiple SubTools at the same time.

SubTools also provide an easy to see visual outliner.

  • Learn more about SubTools here.
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