September 8, 2022
6
 min read

Guide to create a ZSphere skeleton inside your ZTool?

What is character rigging? 

Character Rigging is the art of giving life to your 3d Modelled Characters. It allows you to pose and animate your 3d mesh in a non-destructive way. This means your character can take on all of the different emotions or physical actions that you might want to convey in your 3d artwork.

The process of rigging involves first placing ‘joints’ inside your character which will act as pivot points for your sculpt to move from. You then ‘bind’ your mesh to that internal skeleton by assigning each vertex in your mesh a ‘weight’ for each joint. Adding weights can be done automatically but it often involves painting the surface of your mesh to customise exactly how and where you want your mesh to deform when a certain joint is moved. You can then add controls which your animator would use to move and key frame the joints in a non destructive way so you can always get back to your resting pose. This also allows your rigger to lock off certain joints that you might not want to move independently of each other and also set certain boundaries for how far you can move or rotate something so that you don’t break the mesh. 

In ZBrush, rigging allows for easy editing of your poses, not needing to resculpt if you want to push it further or react to feedback. It allows for an easier and cleaner sculpting process where you can model your character in a T or A ‘rest’ pose where you can  see and sculpt all the details and fiddly parts of your mesh and still pose it afterwards. In most professional VFX, Animation and Game settings all your characters and creatures would be modelled in a rest pose for production then exported and rigged outside of ZBrush to allow for animation in another software. Testing some poses in ZBrush quickly using ZSphere rigs can be really useful to output as concepts for client feedback and sign off without having to start your model again when you move into production. 

ZBrush however does not allow you to add controls or animate within the software and you cannot export your ZSphere Skeleton to any other software to do so, you are only able to pose your mesh in the context of ZBrush. 

Rigging with ZSpheres: step-by-step 

And some good practices to keep in mind

1 - Placing your pivot points: 

  • First start by creating one ZSphere in Draw mode, then swap to Edit mode and open the Rigging tab in the Tools bar.
  • Click Select Mesh and choose the mesh you want to rig from the ZTools listed.

  • Move and Scale your initial ZSphere at the centre of gravity for your character. When rigging in other softwares you might see this initial point referred to as the ‘root joint’

Something to keep in mind when rigging is that joints (In this case your ZSpheres) have a hierarchical structure, meaning the ‘root joint’ will move all the other joints that are attached to it. This means you will want to start by placing your ZSphere where your root joint would be, as all subsequent spheres will be connected to this initial sphere. Your root joint will move your entire character and not deform your mesh, you can use it for things like positioning within an environment or moving characters around each other. 

  • Swap back to Draw mode and start placing more ZSpheres at locations you want your mesh to pivot from, by clicking and dragging a new sphere from your original sphere. This will then create another red ZSphere and a number of grey link-spheres, also known as chains. 

Ordinarily you would want to place spheres where the anatomical joints in your character would be. For example in this human mesh we want to place joints where human joints actually exist, the whole leg for instance pivots from the hip joint, the lower leg from the knee. 

If your character is symmetrical you will also want to turn on symmetry before starting the chains for any symmetrical limbs to save time and create both the left and right spheres at the same time.

  • Swap back and forth from Draw and Move modes to position your ZSpheres, flipping between different views so you can see how the rig looks from every angle.I personally prefer using the shift-snap orthographic views for this. 

2 - Binding your mesh:

  • Once you’ve built a full skeleton with the level of detail you need, you’re ready for binding. Head back to the Rigging tab and click Bind Mesh

  • You should now see your mesh deform as you move a ZSphere. Using the same tools we used to position your ZSpheres, you should be able to move and rotate your mesh into whatever pose you like!

If you’ve ever done any posing or animation in any other software you might find the controls slightly confusing here. When rotating one joint around another, for example to move an arm up or down, you need to click on the grey chain spheres. To twist the chain between the joints you would click on the red ZSpheres that you placed, for example to rotate a hip open or closed. 

  • If you find you aren’t getting the deformations you want click Bind Mesh once more, where it should go from orange to grey showing it’s deactivated. You can then move your ZSpheres around to get a better result. Press Bind Mesh again when you’re happy with your ZSphere placement to test out the new deformations.

Unfortunately in ZBrush you aren’t able to paint skin weights so controlling the deformation of your mesh is a little different to rigging in other software. Re-positioning, scaling and adding more spheres are all ways that you can improve your rig’s deformations and better control the way your mesh deforms. 

If you scale up ZSpheres to the edges of your mesh they’re more likely to hold influence over that area and will help to soften deformations between the ZSpheres.

Adding more ZSpheres can also allow you to be more precise in what you’re moving. Each ZSphere chain moves relative to an initial ZSphere, so after you have your basic skeleton created where your anatomical moving joints would be, you can add extra chains that stem from that skeleton that control any parts of your character that would pivot from that initial point in your skeleton. This can also be useful for clothes, hair, fins or fleshy parts of your character that wouldn’t have an anatomical joint but need to move alongside the body. Often ZBrush users add rib joints in their rigs as underarm deformation is always tricky. 

You can also be thoughtful when modelling your character, keeping limbs angled at least 45 degrees away from the main body can help keep them from being influenced by other joints.

Why leveraging a cloud PC like Flaneer is an asset to create a ZSphere skeleton?

Using a software like ZBrush can require a significant amount of RAM and CPU power to function properly. This can have a high entry cost for hardware which, in turn, results in a high barrier for entry for students and professionals alike. If you couple this with the fact that these types of hardware often depreciate in value quickly and are susceptible to equipment failure, it can be difficult to get started using techniques like those described in this article.

Having a cloud based solution solves all of these problems. Flaneer can provide high end machines available through a remote connection, meaning you can work as if you were using a top spec computer at a fraction of the usual cost. Flaneer machines are also stable and secure, meaning you don’t need to worry about the unexpected costs hardware failures might cause.

ZBrush is a software that only runs on Windows and Mac machines so this can be problematic for artists who use Linux systems as they’re unable to use the software without multiple or partitioned machines. Most VFX artists and studios use Linux systems, if you’re lucky enough to work at a studio they will often provide you with a windows machine specifically for ZBrush. However, you might have to reboot, transfer files from one system to the other or even set up complicated shared network drives to be able to work between the two OS. This can all be solved with Cloud PC solutions like the ones offered by Flaneer. As a studio you then don’t have to maintain an entire windows infrastructure for the use of one application and can make use of other OS specific applications that might have been too much hassle to support otherwise.

As working from home becomes a more desirable job criteria, cloud computing is becoming more and more common and useful. Security is a big priority for VFX freelancers and studios alike. Any data that you have on a computer at Flanner is stored in their secure cloud with logged access, so you know who has accessed any of your data at any time.

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