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GA 3324 : Character Modeling

This course covers advanced modeling techniques for building 3 dimensional characters. Students wil explore techniques of character modeling to include various approaches to figure construction.

 

  
     
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Week 7: High Resolution Detailing in Zbrush


Guerrilla CG: Subdivision Surfaces from Glen Moyes on Vimeo.

 

Intro to the Zbrush Interface
CLICK FOR MORE INFO ON HOTKEYS AND COMMANDS:

In its standard configuration, the ZBrush window is mostly taken up by the canvas. This area is where you will do your painting and modeling.The Palette (Menu) List near the top of the window provides ZBrush's menus, and Trays on either side of the window can be used to dock the menus. The Title Bar at the top of the window provides information and a few miscellaneous controls.

In ZBrush, points on the canvas also have depth, material and orientation and are called pixols.
Pixols are not drawn just as color on the canvas. They are rendered using their distance, orientation and material information. A change in position of the scene lights will affect their shading on the canvas.
Pixels Vs Pixols:

While traditional pixels contain only colo information RGB, and potentially alpha information (see the black area on the lite-brite), Zbrush-pixols can store depth as well, just like we see in the bed-o-nails toy above. The Pixol of course can also store color. CLICK HERE FOR MORE INFO ON THE PIXOL

An example workflow is as follows:
Import a low-resolution base mesh.
Subdivide it several times, possible taking the polygon count into the millions.
Sculpt in fine details at the highest level of subdivision.
You may then decide that some of the base geometry is unsatisfactory; for example, your hero's muscles should be larger than they are.
So, switch to the lowest level of subdivision, and sculpt in those bulging biceps.
Now, when you go back to higher levels of subdivision, the throbbing veins and almost invisible muscle striations will still be visible!
Now, go back to your lowest subdivision level, generate a normal, displacement, or bump map, based on your highest-resolution version of the model.
Export the modified lowest-resolution model to preserve the sculpts you've made on it.
Use the modified model and the new maps in your external program.

ZBRUSH PALETTE REFERENCE from Pixologic, CLICK ON IMAGE BELOW:

 

ZBRUSH BASICS Video Tutorials from 3dTotal, CLICK ON IMAGE BELOW:

 

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

 

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

    If GoZ is installed, you can use the GoZ Icon in the Maya Shelf to send your selected objects over to Zbrush Automatically.


    Then in Zbrush, you can use GoZ to send the mesh back to Maya



    GoZ Video Tutorial:




  2. Let’s begin by opening your Ztool in ZBrush. Models in ZBrush are defined as tools. If you are beginning with a mesh that was initially modeled in another application, import it as an OBJ file by using the Import button under the Tool menu (or use GoZ as specified above).



  3. Now, click and drag on the canvas to draw your tool (see image above). Immediately go into edit mode to allow the tool to be edited as a 3D objec. Press the ‘t’ key on the keyboard or press the Edit button on the top part of the shelf.



    One of the first things I do when I am roughing out a model is to use the Move or Move Elastic Brushes to push parts closer to the form that is desired. See the video below for more information.



  1. Detail with brushes, and use reflection. To Turn on Brush Symmetry, go to Transform and hit Activate Symmetry (or use the hotkey: X).
    You will now notice a second "dot" on the other side of your model which is your reflection.



  2. Work on lower levels of detail first, and only later on higher levels.

    The best workflow for sculpting is to set your mesh to the lowest level of detail first and sculpt as much as you can before dividing it again. This will ensure the retention of forms and also an optimization of your polygon count needs.
    You will start with a super low poly mesh in Maya. Try your best to keep it as low as 150 quads! But as you see in the diagram below, that is well more than enough to start devolping a creature:

    ZBrush offers an additional powerful feature when using subdivision with polymeshes; a polymesh retains a subdivision history. To put it another way, each time a polymesh is subdivided, the geometry from the previous polymesh is remembered, all the way back to the original polymesh. So a subdivided mesh can have multiple levels of subdivision, equal to the number of times it was subdivided plus one for the original level.
    You can move back and forth between these subdivision levels as you model; if you need to make 'large-scale' changes to an object, such as raising a significant portion of the surface, you can do it at a lower subdivision level where the model's polygons are relatively large (more of a 'cage') while fine details can be sculpted at a high subdivision level. In either cases, changes will be propagated across all levels, so sculpting geometry at one level does not lose the work you've done at another level.

    Subdivision levels are also used to generate bump, displacement, and normal maps. Detail is added to an object at a very high subdivision level (possibly with many millions of polygons). That detail can then be compared against a lower subdivision version of the same model to generate a displacement or similar map. Once generated, that map can be taken to an external program and applied to the lower-poly-count model to give a detail effect almost indistinguishable from the high-level sculpting in ZBrush.

  3. Sculpting is done primarily through the funtions in the Brushes Palette. Here I have the ability (while in edit mode) to use any of the following brushes:



    Here is a look at how a few of those brushes work:

 

Sculpting

The best workflow for sculpting is to set your mesh to the lowest level of detail first and sculpt as much as you can before dividing it again. This will ensure the retention of forms and also an optimization of your polygon count needs.

The sliders the top of the shelf (seen in image below) can control the intensity of your brush stroke.

MRGB- when pressed, you are painting Material and Color
RGB- when pressed, you are painting just color
M- when pressed, you are painting just material
RGB Intensity- the opacity of your paintbrush

Zadd- your brush sculpts outwards
Zsub- your brush sculpts inwards
Z Intensity- how deep or high your brush goes

Focal Shift- Controls the softness of your brush
Draw Size- Controls the size of your brush

 

Using Masks to aid in sculpting:

 

 

 

 

 

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