Rigging a Scorpion Mech: Part Two, Head Setup

Xray view of head setup

For this part, I’ll go into my detail on my initial rig for the Scorpion’s head, which compose of the mandibles, face, and the wicked tubing and pistons attached to the skull. I decided to tackle this part of the character early since it’s likely the most complicated part of the overall rig, in terms of joint setup.

Most of the joints are pretty straightforward; the mandibles and teeth consist of FK joints. Most of the complication I mention comes from the tubes and pistons connected to the neck. As the head rotates, the side pistons should shift and pivot, and the tubing should bend without clashing into any geometry. For the pistons, I used basic aim constraints that pivot from the connecting ball joint; this way, they stay oriented like a real piston. The tubing is rigged to a Spline IK system, whose curve is smooth bound to a regular IK chain that bends with the head. If I were to use the pole vector IK by itself, the bending in the tube would be too sharp. By layering a spline on top of the basic IK, the resulting bend has a natural curve to it.

The tubing bends when the skull rotates up. The purple joints are standard IK, and drive the bound skeleton.

The head model has a pretty high poly count. Even when smooth bound to the skeleton with a max influence of one (pseudo-rigid bind), there’s still a significant lag moving the rig around in Maya. That in mind, I decided to build a proxy of the head. The lower poly count and the lack of a skinCluster (via parenting pieces to the skeleton, as opposed to skinning) to calculate should keep the FPS high, which will be useful in animation later.

Side by side comparison

Original Resolution Head: 139k Polys. Proxy Head: 4k Polys

That’s the head for now. So far, nothing in the setup is set in stone; so if I second-guess anything, I’ll be sure to post them! Stay tuned for more updates!

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