FAQ

From ZBrush Info

Frequently Asked Questions

Get answers to the most commonly asked questions about ZBrush. To learn more check out [www.zbrushcentral.com ZBrushCentral].

General

What is ZBrush?

ZBrush is both a modeling and painting program, with unique features not found in other graphics programs. In particular, ZBrush can work with models that have up to several million polygons, and its painting features allow not only standard painting operations, but painting "depth" onto the canvas as well. This can be used to advantage in both scene composition and in modeling very fine details.

ZBrush 2 Performance Tips - Getting the Most from Your System

Optimal Settings

• Multi-Processing. For systems that are capable of multi-processing or hyper threading, this feature can significantly enhance performance. It is a good idea to run the "Test Multithreading" button located in the Preferences>Performance menu. ZBrush will then tell you whether or not multithreading is recommended for your system-configuration. If it is, then both the Draw and Render options should be activated. Note: As of this writing, these settings are not saved with the preferences. Instructions for what to do are given below.
• Undo/Redo Settings. Setting these values incorrectly is the most common cause of frequent "Compacting Mem" Messages. This message is displayed whenever ZBrush has to write to disk rather than being able to use RAM. The way that the Undo settings work is that they tell ZBrush the minimum number of undo's to keep available for you. Wherever possible, ZBrush will make more than that available. However, as your mesh reaches higher numbers of polygons, ZBrush will be forced to make a decision to either reduce the number of available undo's or start writing to disk (which is much slower than RAM). The higher this value is set to, the more often ZBrush will be forced to use your RAM for storing undo information rather than mesh information, which degrades performance. It is highly recommended to leave this value at the default and only change it slightly upward if you know that you absolutely want to have more undos available at all times.
• MaxPolyPerMesh. ZBrush checks to see how much RAM your system has and determines a recommended mesh density. Exceeding this density (which is shown in millions of polygons) can be done by increasing the slider setting. It is not recommended to increase this setting to more than double the recommended value.
• Threshold Settings. There are three sliders in the Performance menu that affect how ZBrush handles models with multiple subdivision levels while you're working with them. These settings are optimized to provide most users with the best possible performance, but you are able to modify them if you need to. As a general rule, these values should be set to lower values for better performance.

QuickAndDirtyEdit. This preference in the Performance menu is turned on by default and makes the renderer perform as fast as possible while editing 3D objects. It is recommended that you leave it active unless you are noticing artifacts that would affect your work.

Optimal Workflow

• Quick 3D Mode. Whenever you are editing a model (especially one with high resolution) the "Quick 3D Mode" button should be pressed. It's located on the top shelf by default, next to the Polyframe button, and is pressed by default. This mode allows ZBrush to use faster rendering routines. Only turn this feature off when you wish render-time smoothing to be applied to the mesh (such as when you're going to snapshot it to the canvas).
• Partial Mesh Visibility. When working on high resolution meshes, it is very beneficial to hide a portion of the mesh and only keep visible that part that you are currently working on. This not only accelerates ZBrush's interactivity, but also reduces the amount of RAM that is required while editing the mesh.
• Fast Render Mode. The Render palette makes four rendering options available to you. Preview is selected by default, which renders materials in real time. Of course, that extra information also means that some system resources are not being devoted to modeling, and can slow performance down when working with a really dense mesh. For modeling purposes, you are usually more interested in shape and so don't need the material rendering routines. Changing to Fast render mode will speed up interaction with your mesh. It is recommended to use this setting for long modeling sessions; especially when working with a large document size.
• Fast Shader. This material is partway between the Fast and Preview renderers. Like any material, it instructs ZBrush's rendering engine for how to deal with light on the surface of your model. However, it has fewer modifiers than most other materials and so will render faster in Preview mode. Note that using this material in Fast Render mode will not make a difference, since that render mode ignores any material selection, including the Fast Shader. It is recommended to use this material for long modeling sessions; especially when working with a large document size.
• Sharing System Resources. If other applications are active while you are actually working with ZBrush, you may experience slower performance because a portion of your system resources are being reserved for those other applications. Exiting other applications (including unnecessary items in the system tray) will free the CPU time and memory to be used by ZBrush.
• Saving the multiprocessing settings.
  • As mentioned above, the multiprocessing systems are not currently saved with the preferences. This will be handled by an updated Test Multithreading script, which will be released in the future. Until then, there are two simple options for you, if the test shows that multithreading is recommended.
  • First would be to simply hold down the Ctrl/Cmd key and drag the MultiDraw and MultiRender buttons onto your shelf. Save the preferences, and you will now be able to immediately activate them at any time that you want the extra performance that they provide.
  • The second option is to modify your default ZScript so that the settings are automatically enabled every time you start ZBrush. To do this, simply open the DefaultZScript.txt file in any text editor and replace it with the following:

/*===========start===========*/
// Activates MultiThreading at startup

[VarDef,MultiThreadingInited,0]
[If,!MultiThreadingInited,
    [VarInc,MultiThreadingInited]
    [IPress,Preferences:MultiDraw]
    [IPress,Preferences:MultiRender]
]
[pd]

/*===========end===========*/ 

What FILE FORMATS does ZBrush 2 support?

• For 2D images, the BMP, PSD, PICT and TIFF formats are supported. When exported from the Alpha palette, the TIFF format is a 16 bit image ideal for use with displacement maps. In addition, ZBrush will import the JPG format. Multi-layer PSD images will be flattened on import since ZBrush's layer system is very different from Photoshop's.
• For 3D objects, ZBrush supports OBJ and DXF. The OBJ format is the most common, since it supports UV mapping (ZBrush will use any UV mapping that's applied to the model, or can assign UV coordinates itself). Additional formats will be possible in the future through plugins.

Modeling

I've drawn a model on the canvas, but when I try to do something with it, I just get another copy of the model, or can perform only basic operations such as rotation and scaling. What do I do?

This results from the dual aspects of ZBrush, painting and drawing. When you first put a model on the canvas, you are "painting" it. If you then attempt to do something on the canvas, that counts as another paint stroke, and you will get another copy of your model. This allows you to rapidly create scenes such as a field of flowers, from a single flower model.
To sculpt a model after drawing it on the screen, you need to go into 3D Edit mode--the t key toggles between 3D Edit Mode and paint mode, or use the Edit button that appears above the canvas.

I forgot to go into 3D Edit mode to sculpt, and now have an extra copy of my model on the screen. How do I get rid of it?

This is a common question for people who have just started with ZBrush; you'll quickly get into the habit of immediately going into edit mode after placing your model on the screen. In the meantime, just hit Template:Key:Ctrl n to clear the canvas, and then redraw the model and go into edit mode, as described above.

I've scaled my model, but when I export it, it is the same size as it was when I imported it. How do I change the size of my model in ZBrush?

The standard "scaling" operations in ZBrush are really just zoom operations. When ZBrush imports a model, it internally and invisibly scales it to fit in a 2x2x2 cube. This allows maximum accuracy when working with very high resolution models. When the model is exported, it is rescaled again, to come out at the same absolute size as the original model.
Normally, you will not need to change the absolute sizes of models in ZBrush. In fact, since ZBrush has no built-in absolute system of measurement, it is difficult to do so. Such an operation can be done very quickly and easily in an external program.

I've seen the fine detail that can be achieved with ZBrush, but can't see how to do it with the sculpting tools. How is this done?

Very fine detailing in ZBrush is normally done with Projection Master, a plugin that ships with ZBrush. With it, the model is "dropped" to the canvas, where it may be painted with all of the ZBrush paint brushes. Since these brushes can affect canvas depth in an infinite number of ways using Alphas, almost any kind of desired detailing can be achieved. Colors and other properties can also be painted.

How should I SAVE MY MODEL so that I can edit it later?

Save it using the Tool>Save As button. Saves using the Document palette only save a snapshot of the model rather than the full 3D data that's necessary for continued sculpting.

What can I do to IMPROVE PERFORMANCE when sculpting high resolution meshes?

First, hide the parts of the mesh that you aren't working on at the moment. Fewer visible polygons means faster performance. Second, try not to rotate your model at a high subdivision level. Instead, go down a subdivision level before rotating the mesh and then go back up in level to continue sculpting. You may also find that it helps to hide and unhide parts of the mesh when you are at a lower subdivision level. Also, the Preferences>Performance menu has several sliders for fine tuning ZBrush on your system. Hold down the Ctrl key and place your pointer over each to learn what they do. (Note: If you adjust QTransThreshold1, QTransThreshold2 and QEditThreshold, be sure that they become progressively higher. Setting all three to maximum will actually degrade performance.)

How can I CENTER MY MODEL on the canvas?

Alt click on any blank part of the canvas. You can also click once on the Move or Scale buttons that are located on the right shelf in the default configuration.

How can I RESELECT AN OBJECT or have more than one editable object?

This question is covered in depth in this thread.

Texturing

My texture wraps okay, but there's a THIN LINE at every UV SEAM.

Before exporting, press Tool>Texture>Fix Seam. This creates a 4 pixel buffer around all of the UV edges. If necessary, you can change the FSBorder setting to modify the border width. If you still have seams appearing, even after applying the Fex Seam operation, then you should make sure that texture antialiasing is turned off in your rendering engine. It might also be necessary to turn off MIP mapping.

Can ZBrush paint BUMP MAPS?

The only difference between a bump map and a displacement map is how it is used by your rendering engine. To create a bump map, follow the steps to create a displacement map and export the resulting alpha. ZBrush can also apply the current alpha to a model as a bump map for rendering in ZBrush. Follow the regular steps for applying a displacement map, but leave Tool>Displacement>Mode turned off.

My texture is JUMBLED when applied to my model in my other software.

Different programs use different coordinate systems. Before exporting your texture from ZBrush, try pressing Texture>Flip V. This will allow the texture to wrap correctly in most programs. If it doesn't, try Flip H instead, or a combination of the two.

How do I work with MULTIPLE TEXTURES on the same object?

ZBrush currently allows one texture to be wrapped onto a model at a time. If you have a model that uses multiple maps, then any texture that you apply will wrap correctly onto one part of the model and incorrectly onto the rest of the model. This doesn't affect your ability to texture the model, though. Simply paint one map at a time. You can even hide the other portions of the model so that they aren't distracting you while you work on the current texture.

What do you mean by "UV REGIONS"?

UV Regions are a means of applying multiple maps to the same model without using material zones and overlapping mapping. The premise is that each region occupies a range of coordinates. The most common region is the default of 0,0 through 1,1. However, other regions are possible such as 1,0 through 2,1, 0,1 through 1,2, or even 0,0 through -1,-1. For rendering engines that support it, a single model can have dozens of textures without any overlapping coordinates. This kind of mapping has an added benefit in ZBrush in that you can use it to assign polygroups to make life easier for texturing and sculpting. Press Tool>Polygroups>Uv Groups, and ZBrush will assign each region to its own mesh group.

How do I ASSIGN AUVTILES OR GUVTILES?

Since these two mapping methods are precision techniques, it is necessary for ZBrush to know what size the texture will be before the coordinates are assigned. You should begin by creating a base texture of the desired size. In the Texture palette, enter the width and height of the texture that you will create, and then press New. For best results, the texture dimensions should be a power of 2 (256x256, 512x512, 1024x1024, 2048x2048 or 4096x4096). After you have created the base texture, go to Tool>Texture and press the AUVTiles or GUVTiles button. That's all there is to it! Before setting the mapping, you can also set the AUV Ratio slider. This causes polygons to be mapped to different sizes on the texture depending upon their relative sizes in the mesh. If you are going to be displacement mapping your model, it is recommended that you leave this setting at 1.

Displacements

What is the MULTIDISPLACEMENT PLUGIN?

It is used to create multiple displacement maps for the same model, when that model has been UV mapped with multiple regions. For example, the head might use coordinates 0,0 through 1,1 and the body coordinates 1,0 through 2,1. This makes it possible to create several displacement maps for the same model, for rendering engines that support such mapping.

What is the PURPOSE of a displacement map?

Displacement maps take bump mapping to the next level. The problem with bump mapping is that it only performs displacements toward the camera. As a result, the profile of your model is not changed. Displacement mapping can move points or pixels in any direction, which changes the silhouette of the model and creates a more realistic effect. In addition, animation packages can't handle the huge numbers of polygons that ZBrush supports. Displacement maps are the key to overcoming this weakness. You would rig and animate a low poly version of your model with very little drain on your system resources. At render time, you would then apply a displacement map to make the finished scene look like you'd actually animated the ultra high resolution ZBrush version of your model. In short, displacement maps make it possible to greatly increase the realism of your scenes with minimal impact on your system resources.

What is the difference between ADAPTIVE mode and DPSUBPIX?

The adaptive mode should be used when you have applied disproportional modifications to your mesh (such as by extensive use of Pinch brush). If your mesh deformation is fairly uniform, you'll get faster results with adaptive mode off. Furthermore, you'll be able to use the DPSubPix option to virtually subdivide the mesh to much higher resolution (even if your system can not normally handle such resolution). Each DPSubPix level increases the virtual resolution of the mesh by 4. For example, a 1 million poly mesh with DPSubPix set at 1 is similar to the result that you'll get if the mesh had 4 million sub-polygons, DPSubPix of 2 will produce results similar to 16 million sub-polygons. DPSubPix of 3 is similar to 64 million sub polygons.

Can I use a NORMAL MAP for the fine details?

Yes. What you would do is sculpt your high resolution model and create a normal map for it. Save the tool so that you can come back to the high resolution version later if you need to. Now switch to a medium subdivision level and delete the higher levels. Create a displacement map. You'll now have a displacement map for medium frequency details and a normal map for high frequency details.

How do I CREATE a displacement map?

Please see part 3 of the Telephone tutorial in the ZBrush 2 Practical Guide. There is also a ZScript tutorial available for you to watch, which can be found via ZBrush 2's built-in Help browser. It's called "Displacement Mapping Tutorial."

Interface

How do I MOVE THE CAMERA?

Canvas

You can pan the canvas by holding down the spacebar.

You zoom in and out of the canvas by using the and - keys on your keyboard.

Pressing 0 will return you to 100% magnification, and Alt 0 will activate ZBrush's special AA Half antialiasing display mode.

Bear in mind that zooming into the canvas will cause pixelation as the individual pixols are enlarged. Rather than moving the camera around the model, ZBrush uses a principal of moving the model in front of the camera.

Model

You rotate your model in edit mode by pressing and holding the left mouse button and clicking and dragging outside of the model. If the model fills the entire canvas just click and drago outside of the canvas area.

You can move a model in edit mode by holding down the Alt key then click and drag on the canvas.

To zoom/scale the model, you also use the Alt key. The technique is to hold down the Alt key, click on the canvas, then release the Alt key without releasing the mouse click. When you drag up and down, the model will be resized.

To center the model on the canvas (even if it's been moved out of sight by accident), Alt click on any part of the canvas or click once on the Scale or Move buttons on the right shelf.

If any of these methods of rotating your model are difficult just use the Move, Rotate, Scale buttons on the right hand side of the interface. Also, press CTL while hovering over the interface item to learn more about and remind yourself of the hotkeys.

Can I customize the interface and CREATE MY OWN PALETTE configurations?

Yes. The shelf is designed for you to be able to place any interface elements on it, including those that have been created by a plugin. There are four parts to the shelf: above and to either side of the canvas, as well as at the extreme bottom of the screen beneath the ZScript window. Many more opportunities are also available for customizing the user interface. The ZBrush 2 Practical Guide explains in the chapter on customization how to make use of these powerful features. You will also find more information in this thread.

What CAMERA FORMAT does ZBrush use?

ZBrush's camera is orthographic. While the gyro is active, perspective can be simulated using the Draw>Persp button and its associated slider. Perspective is not available when the object is in Edit mode.

Does ZBrush have MORE THAN ONE VIEWPORT?

ZBrush's pixol technology would not work with multiple viewports. For this reason, ZBrush has the main viewport, only. The fact that your models are only viewable from one angle also means that ZBrush can focus more resources on polygon manipulation, which makes it possible to have more detailed models than would be possible in a multiple viewport system. However, there is a ZScript available called QuadQuick that simulates a multiple viewport environment within ZBrush. There are plans to update this for Z2 as a plugin in the near future.

Can I set ZBrush to LAUNCH with a DIFFERENT DOCUMENT SIZE?

Yes. Not only that, but you can set it to have any number of layers, lighting configurations, etc. This is all accomplished through the StartupDocument. The ZBrush 2 Practical Guide explains in the chapter on customization how to make use of this powerful feature.

Projection Master

Projection Master doesn't fade the texture when I pick it up even though I had fade on.

Answer: In the Tool palette, under the Display Properties tab make sure that you set DSmooth above 0. It can be .01. This will enable fade when you pick your model up from Projection Master.  :)

What advice can you give for Softimage|XSI, MENTAL RAY, MAYA, LIGHTWAVE, VRAY, RENDERMAN and MAYAMAN, POSER, CINEMA 4D, and 3D STUDIO MAX?

This question is covered in depth in this thread.

Other Apps

Can UV MAPPING be done after the high resolution model has been sculpted?

Yes. All you need to do is go to subdivision level 1 and import the version of the base mesh that has the UV's that you want. Do this before you create your displacement or normal map. Alternatively, you can apply one of ZBrush's mapping methods.

When I import a model into ZBrush its ORIENTATION is different.

ZBrush 2 has the Preferences>Importexport menu, which makes it possible for you to synchronize ZBrush's coordinate system with your other software. Settings are available for both importing and exporting. Incidentally, ZBrush also offers several scaling options, which you can read about in this thread.