Rigging in Production Speak

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This is a post for all the production Co-ords out there first time dealing with a rigging department.

You’re most likely finding a whole new bunch of terms being used by the riggers that make little to no sense. Which is cool even trying to dumb things down is hard; and this post is about trying to do just that.

Lets see how we go.

Rigging Terms:

Geometry

The model from the modelling department.

Rig

Serves both the rigging department as well as the animation department: eg:

    Control Rig - The things in the rig animators will move around
    Guide Rig - The things in the rig the riggers use to fit the ctrls to the geometry

Fit

A term used when placing the rig into positons that match the geometry, eg: shoulder, elbows, wrist, fingers etc

Reference

A Special import in Maya that is really more of a pointer to a file to load into the current rig. Updates can there fore
be handled by updating the reference.

Transform

Just think of this as a point in 3d space.

Node

You'll hear that a lot. In modern 3D apps nodes represent all kinds of things (mathy) etc. Just think of this as a
way to collect a whole bunch of processes together (or just something simple like a+b) into a single container in the 
application for the artist to use. They have inputs, and outputs. eg:
Addition Node:
    Consider an addition node A+B
    inputs are A and B
    output would be the result of adding A+B together.

Constraints

Various special tools in an application that state `this part of the geometry can follow the rig via this constraint`

Deformation

When you smile and then frown, your face is `deforming'. When a rig ctrl moves the rig, the rig deforms the geometry 
in a way to procure a desired result.

Joints

A bunch of special transforms that get used to connect the rig to the geometry.

Skinning

Uses joints to connect the rig to the geometry by stating `this joint affects this part of the mesh by this much`

Blendshape(s)

If you stand in a mirror and don't have an expression this would be considered the baseShape of your face. Then you 
smile. That's another shape of your face. Frown / Purse your lips ... and so on. Each of these are called a blendshape
and they're are modelled either by a modeller or a rigger. The blendshape node takes care of morphing between these shapes.
0-1 values. The rig connects to the blendshape in a more artist friendly manner.

PSD

Pose Spaced Deformation. It's a method used to drive new blendshapes that are over the top of the final result of the 
 rig's deformation to cleanup bad volume in elbows/hips/shoulders etc etc

Corrective (shape)

Depends on how these are being implimented, but essentially these are blendshapes that correct deformation. Note if the 
underlying systems (skinning etc) alter what these were originally built on, they may need to be redone.

Checkin / Publish

Saving the rig to the server's read only area

Why/How some stuff works

So sometimes your rigger is going to tell you it’s 5minutes work, sometimes a day. And sometimes it’s plain confusing as to why something that sounds simple = hard/long to do.

The reason for this is the way things get built from ground up. There are layers to the cake, and if you have to pull out and alter the base layer, the entire cake might not look/taste the same. And when it comes to rigging, once animation have started any changes to the rig must = a cake that looks and tastes the same or animators lose work.

A typical set of layering looks like this;

• Modelling confirm the model is ready = a base set of vertexes in a specific order + UV maps
• Rigging import the model and start a fit of the rig. At this stage nothing is connected to the model.
  • model updates won’t impact the rig unless they change the positions the rig is being fit to (arms, legs etc).
• Rigging start their first pass of connecting the rig the geometry.
  • Constraints? These can happen on groups so the model can be updated into the groups without too many problems etc
  • Skinning? This is where suddenly model changes should NOT includes vertex re-ordering or changing the vertex count. Think of the whole thing as a mapping of sorts. vtx00 is being mapped to joint01, joint65 etc if that number on the geometry changes the rig breaks.
• Rig is pretty much setup, the fit matches the geo, the skinning is done. Now they can start in on PSD/Corrective work
  • PSD **relies on the skin now. If the skinning changes all the PSD/Corrective work changes! Usually not for the best! **

So you get the idea…. If there is a production request to change something, these are the kinds of things that need consideration, and worst case, you’re heavy into animation, and the director changes their mind on a character’s proportions, the model comes back with a vertex change / proportional change and…. all hell breaks loose :)