Local Rigging vol. 1

Recently, I took the course of Optimizing Rigs for Parallel Evaluation on Rigging Dojo by Charles Wardlaw, a very good course by the way. One of the topics that he explains is the local rig. When I started doing rigging years ago ( I feel old now D: ) I made local rigs for many parts of the face without any control, for the eyebrows, for eyelids, for lips, for mouth, for everything. The main problems that I faced was the normalization of the skinCluster and if you don't have a good control of that, it can be a nightmare to edit the rig. Moreover, when you want to move a control and at the same time the joint, you will need to duplicate the setup on the local rig. Since, I built my own autorig system I tried to avoid that, but the main problem of having the whole setup on a single chain is the performance. Obviously, if you want to export the skeleton to a game engine is mandatory to have the whole system on a single chain, but for films is not required.

The skeleton hierarchy of half-life 1 models

I bumped up with the idea of using locals rigs without using direct connections from controls to joints. I discovered two methods that you can use to approach this setup. I divided this into two posts

Reciprocal Driving:

This setup is a bit complex to make, but if you understand it, you will get good results. First of all, you need to make the setup (groups, parents, constrains, etc.) on the local rigging group not in the global rigging. In the global rigging, you will only put the controls and a couple of groups above them. First I will name the transforms that are involved:

• controls = animatable controls
• relative controls = controls on the local rigging
• buffers = group above the animatable controls

The connections will be like this:

1. Direct connection from the control to the relative controls (T,R,S)

2. We will use the parent matrix of the relative controls and we will multiply by itself but static and inverted. The result should be an identity matrix, then we will decompensate the matrix and connect to buffers or use the offsetParentMatrix.

I am using a compose and an inverse matrix, but you can use pymel or openMaya to make this operation

without this nodes

Voilà! You now have a local rigging setup if you want to create more groups above controls, maybe to control them, just create them above the relative controls. The only downside that I found is this only will work if the all the controls are not parented between them.

In the next post I will explain the second method, which is very different from this one. See you there and happy rigging!