ZBRUSH TO MAYA - 3D Links · PDF file3 1. Introduction Welcome to the ZPipeline ZBrush to Maya...

Click here to load reader

  • date post

    08-Feb-2018
  • Category

    Documents

  • view

    221
  • download

    1

Embed Size (px)

Transcript of ZBRUSH TO MAYA - 3D Links · PDF file3 1. Introduction Welcome to the ZPipeline ZBrush to Maya...

  • ZBrush To Maya 32-Bit Displacement Guide

    Scott Spencer

    November 10, 2005

    2005 Pixologic, Inc. All rights reserved.

    Pixologic and the Pixologic logo, and ZBrush and the ZBrush logo, are registered trademarks of Pixologic, Inc.

    Photoshop is a registered trademark of Adobe Systems, Inc.

    Maya is a registered trademark of Alias, Inc.

    All other trademarks are the property of their respective owners.

    Please mail comments or suggestions about this document to doc@pixologic.com.

  • 2

    1. INTRODUCTION ....................................................................................................................................... 3 2. MAYA MODEL PREP............................................................................................................................... 3

    2.1. MODEL REQUIREMENTS FOR ZBRUSH .................................................................................................. 4 2.1.1. Fixing Overlapping UVs ............................................................................................................... 4 2.1.2. Cleaning the Mesh Topology........................................................................................................ 6

    2.2. EXPORTING FROM MAYA....................................................................................................................... 6 3. SCULPTING IN ZBRUSH ........................................................................................................................ 7

    3.1. UV REGIONS AND POLYGROUPS ......................................................................................................... 10 3.2. FINAL UV ADJUSTMENTS AND VERTEX ORDER ................................................................................ 12

    4. DISPLACEMENT MAPS AND THE ZBRUSH ALPHA DISPLACEMENT EXPORTER ....... 13 4.1. GENERATING A DISPLACEMENT MAP ................................................................................................. 14

    4.1.1. Creating a comparison Image to check your Maya Renders ................................................... 17 5. BACK TO MAYA ..................................................................................................................................... 19

    5.1. MAYA SETUP FOR RENDERING............................................................................................................ 19 5.2. CREATE .MAP FILES ............................................................................................................................. 21 5.3. RENDERING WITH A SINGLE MAP........................................................................................................ 21

    5.3.1. Lighting and Test renders ........................................................................................................... 24 6. MULTIPLE DISPLACEMENT MAPS................................................................................................. 27

    6.1. SETTING UP UV REGIONS IN MAYA.................................................................................................... 27 6.2. MAKING THE DISPLACEMENT MAPS IN ZBRUSH................................................................................ 29 6.3. APPLYING MULTIPLE DISPLACEMENT MAPS IN MAYA...................................................................... 30

    7. BUMP AND DIFFUSE MAPS ................................................................................................................ 32 7.1. USING THE BUMP VIEWER MATERIAL. ............................................................................................... 32 7.2. APPLYING BUMP MAPS IN MAYA......................................................................................................... 34 7.3. CAVITY MAPS AND THE DIFFUSE CHANNEL....................................................................................... 35

  • 3

    1. Introduction Welcome to the ZPipeline ZBrush to Maya guide. In this manual Scott Spencer will guide your through a process of exporting your sculpt in ZBrush, for use in Maya with Mental Ray. Scott illustrates the processes he uses to work seamlessly between the two applications. This guide will focus on 32-bit displacement maps which enable real world displacement (no arbitrary scaling factors necessary) and produce the best possible results in achieving the look of your original ZBrush model.

    2. Maya Model Prep If your model started as a mesh in Maya, begin by loading your model in the Maya workspace. We will need to export the geometry as a generic 3D format that ZBrush can read. Maya will export OBJ files for this purpose. The OBJ exporter is a plug-in which must be loaded. The mental Ray renderer is also a plug-in we will load at this stage so it will be available when needed.

    Figure 1. Model Loaded Into Maya

    To load the object exporter and the Mental Ray renderer go to Window>Settings and Preferences> Plug-in Manager. This will load the Plug-in Manager window as seen below. The OBJ plug-in is called objExport.mll and the Mental Ray plug-in is called

  • 4

    Mayatomr.mll. Click the loaded checkbox next to each to load them now, you may also want to click auto load so they are available every time Maya starts.

    Figure 2. Plugin Manager Window

    2.1. Model Requirements for ZBrush There are two requirements your model and UV map must require before they can be used in ZBrush:

    The mesh may only have one UV set and the UVs may not overlap at all. Overlapping UVs will cause unexpected crashes when you are extracting your displacement map and they are easy to miss.

    and

    The model should consist of just quads and tris, with the tris being in well-hidden regions.

    2.1.1. Fixing Overlapping UVs It is entirely possible to use ZBrush AUV tiles or other automatic options for our mapping but as you will see having UVs laid out in Maya will open up several workflow possibilities not otherwise available.

    Here is an example of overlapping UVs in the toes of this model. This must be corrected before the displacement map may be extracted. Otherwise this small overlap could cause a crash.

  • 5

    Figure 3. Overlapping UVs in the Maya UV Editor Window

    It is important to note that unless you are painting color maps ZBrush is not concerned with UV coordinates until you extract the displacement map. This leaves you free to model in ZBrush then lay out UVs later or change your UV layout without losing all the work you applied to your model. ZBrush also offers a tool to check for overlapping UVs under the tools palette, Tools:Texture:UV Check. Clicking this button will highlight in red on your model any overlapping UVs so you know where to look for errors back in Maya. When performing an inspection like this in ZBrush, make sure to rotate your model to view all surfaces.

    It is also possible at this phase to place your UVs outside the 0 to 1 texture space. This will allow you to map your mesh in ZBrush for easy masking and hiding as well as allow you to maximize texture space and extract maps for each body part instead of a single map for the entire model. This is discussed in section 6.

    Again, remember you are never locked into a UV set with ZBrush if you are just sculpting. You can import your OBJ at level one with any UV layout as long as the vertex order of the mesh remains unchanged. (Generally, this means that you can move points in the level one OBJ, but cannot add or remove points or edges, otherwise change the geometry of the model.) More information on vertex order can be found below.

    Below is an acceptable layout, using the mesh with automatic mapping. The UV shells are all in the dark gray square, the 0 to 1 range. This will generate a single map in ZBrush that applies to the entire mesh. Later well talk about how to spread the mapping across multiple meshes by mapping out side the 0 to 1 UV coordinate range.

  • 6

    Figure 4. UV Map with U and V Coordinates Each From 0 to 1

    2.1.2. Cleaning the Mesh Topology The mesh needs to be clean. By clean I mean it should be all quads or at least nearly all quads. Avoid tris, poles (points where 5 edges or more meet) and n-gons (faces with more than 4 edges). If you find you must have a tri, hide it in an inconspicuous area. Leaving in any of the above elements may cause artifacts at render time. You also want to ensure your vertices are all welded and there are no nonmanifold or lamina faces. All of these mesh issues can be resolved with the cleanup tool. Go to the Polygons menu in the modeling subset and select the cleanup option box.

    Figure 5. Opening the Cleanup Menu

    This will open the Cleanup menu. If you set to Select and check only the 4-sided faces option box, Maya will select all the quads in your mesh. You can then use Edit>Invert Selection to select the non-quad faces. Often I will assign another color to these faces to keep them visible and keep working with the topology until I have an all quad mesh.

    In the same cleanup menu choose the Select and Cleanup option and select Nonmanifold Geometry and Lamina faces. Click Cleanup and this will resolve any of these issues which often arise when modeling with the extrude tool. Cleaning up your mesh now can save a lot of headaches later on.

    2.2. Exporting from Maya With the UVs and the topology ready you can now export the mesh from Maya. To export go to the File>Export selection option box and select the OBJ option from the drop

  • 7

    down menu. Click Export Selection and save the model. You are now ready to import the mesh into ZBrush as a Ztool.

    Figure 6. Export Options

    3. Sculpting in ZBrush Lets b