Fenric has created for us a very powerful animation automation tool with the Carrara ERC plug-in. As such there are some great advanced examples available on the Internet that at first make it appear very daunting. However, the core concept of ERC is very simple; thing A moves thing B or more accurately thing A controls/modifies thing B. ERC is basically acting like the string between a puppet and its human master.
In the Carrara world the master can be anything that can be animated using the keyframe sequencer. For example this could be the arm of an evil sorcerer in our scene. The puppet can be, once again, anything that can be animated using the sequencer. In our first example let’s say the puppet is a chair in our scene. I can use ERC to magically levitate the chair whenever our character raises his arm (yes, this is a truly evil sorcerer). To do this I would simply connect our string (ERC) from the shoulder rotation of our sorcerer to the Z-axis position of the chair. Now whenever our evil sorcerer raises his arm, our chair flies up into the air and off our screen. Not exactly what we had in mind; we were going for some low altitude levitation. To fix this, ERC allows us to do some fancy things with our string. It allows us to change the degree by which the arm movement changes the chair movement. So we can tell ERC that we want our arm to move the chair only a small fraction of how much it was moving it before, even though our arm movement will remain exactly the same.
But wouldn’t it be simpler to just animate the arm and then separately animate the chair? Probably, but it made for a good example. One of the real indispensabilities of ERC is in the animation of things that are associated with each other on a repetitive basis. Let’s look at a face for example. When we move something on our face it typically causes other parts of our face to move as well. When I raise my eyebrows I get big wrinkles on my forehead. When I smile, same thing, my eyes wrinkle. Unfortunately I find this association to be far more desirable on my 3D characters than on myself and while I can’t do anything about me, I can use ERC to emulate these associated facial movements on my Daz characters.
Daz characters have an abundance of morph parameters that can control virtually all aspects of the face allowing us to get very detailed with our automated animations by setting up an ERC modifier to control anything we want; from anything we want.
Additionally, because Carrara shaders can be animated, we can create an effect that mimics fine wrinkles on our characters face. We could setup a face bump map using the regular bump map and a second bump map with additional wrinkle lines and then use an ERC modifier to mix between the two as our controlling parameter (mouth movement) changes.