Welcome to the Inspired 3d Advanced Rigging and Deformations blog.

Readers can view the latest errata here

And of course can download the book files and errata doc at the publisher website at the link below.
note the publisher has changed the site and the download paths mentioned in the book are no longer correct.

I realized that there was not a table of contents available for the book so I have uploaded a .PDF for any one wanting to know what we cover in detail.





BOOK: Chapter 6- Rigging Reference -Mechanical rigging

In our book we did not have time or space to talk much about mechanical rigging but we did talk about how to find reference and how to think about rigging up non organic characters.

Here is the excerpt from the book:
So far we have been talking about finding references for organic or living characters and the need for proper joint placement for deformations. We have
not discussed the topic of mechanical rigging and the slight differences that you might deal with when mapping out a robotic or mechanical character.
The same ideas about finding real references for the kind of mechanical joints you will be setting up apply as they do for organic characters. However,
mechanical objects have engineered systems that need to work together and feel like they have a reason to exist. The gears, pistons, or cables need to feel
like they work, are controlling the object, and have a purpose for being where they are on a robot or vehicle. It is up to the Character TD to work out
mechanical systems that animate well, but at the same time keep the animators from having to rotate and hand keyframe all the mechanical bits in the asset.
Take, for example, a robotic suit used to move heavy objects found in so many science fiction movies. If you have to rig up this kind of heavy equipment,
then real construction equipment provides a great reference for how your model parts rotate and pivot, as well as how tightly they are attached or how they
interact as part of the whole. And construction equipment should be easy enough to find. In a big city, you might look at cranes or fork lifts. Even in the
country, a tractor would server as a good reference. Any equipment that is large enough to demonstrate the working relationship between heavy moving
parts should suffice.

The reason I am posting this is because I was reading an article at VFXWorld on the golden army characters in the Hellboy II and found a quote that fight right in with the paragraph above.

"The rig that we animated with was pretty complex; not like a human rig. There were a lot of specific, machine-like movements required to get it to look robotic and able to move well enough to get the performance that Guillermo wanted." Fortunately, Davis was able to find some inspiration on his morning journey to work at Double Negative's studios in the Soho section of London. "It's across from Chinatown, and luckily they were tearing the roads up there, so on the way to work I could watch the big machines. They had a lot of high-tension, stiff joints. When they made a sudden stop, I could see how the force resolved itself within the machine."

The DNeg animators also looked at references on robotic arms, noticing how when they stop after completing a movement, there's a bit of oscillation as it comes to a stop. "We animated a lot with FK -- forward kinematics -- and not inverse kinematics," explains Davis. "IK would tend to give a lot of movement in the elbow, like a puppet, which makes the arm look a little weaker."

© 1996 - 2008 AWN, Inc. All rights reserved.

It was a very small part of the book but I did not want the information to be overlooked.

Added bonus:
The Crazy Elevator rig is a complicated expression to create an automated elevator for The Red Star game environment. Tre Z did the model and I, with some math help, got it working 99% automatically, with an extra layer for keying the start and end. The artist could just move the elevator shaft and it moved the pulleys, rotated gears and was a quick way to add some life to the environment. Teaching some basic rigging and tech work to game environment modelers can take the workload off of animatoin and rigging and at the same time create a much more interactive world.

Watch: Crazy Elevator rig movie


TIP: Skin control/muscle under skin and Cartoon silhouette control all from one idea!

Update: I wanted to mention a few notes on this rigging experiment and expand on my notes a bit more for anyone who has looked in to using this method. 
There are two things to watch out for, one is that if you try to rotate a character the rebuild curve node code can't rotate the rebuilt curve as the component cvs rotate and it will cause shearing.  The workaround for this is to create strips and do rebuild surface instead of curves, same method just with surface, it works great.

Or create a local , no moving version of the rig fixes that are then fed in to the final rig as a blendshape. This lets the curves be used more in a shaping control mode vs. skin fix.  I realized this was not clear in the original post and I had thought the bug was a diffrent issue at first.

Here is a small trick that has lots of potential to help improve deformations with out a lot of extra work.

Influence object rebuilt surface technique: (updated)
This is not a replacement for muscle simulation but it is in my experience much faster to setup and visually looks better than other solutions I tried, advantages include topology independent, the surface can be mirrored and the weights can be also using built in Maya tools (2008 and up) and for speed of playback they are easy to turn off.
  1. Build a nurbs surface; either using extracted character mesh curves with the "edit-convert-edge to polygon"  or edit a nurbs surface (divided plane) to following shape of character mesh.
  2. Rebuild the surfaces with history, the result surface will be used as an influence object eventually.
  3. The Base (original surface) gets skinned to the characters skeleton. Do this with weights->copy weights from the skin mesh your adding this influence object to have it mach what the skin is doing all ready.
  4. This surface can be offset/translated away from the outside of the mesh so that it helps to keep the skin volume along with allowing us to see the separate control surface and the rebuilt influence surface.
    Since it is offset away from the base surface you before you add it as an influence it will not cause an offset deformation in the mesh.
  5. The rebuilt surface becomes the character mesh influence object (using components, so make sure you turn on "use components" on the skin cluster and check your "add influence object- settings").
  6. The history of the surface (spans/curve type/etc) can be SDK driven so that the skinmesh is looser or tighter to the original shape, once weights are painted to it. Or you can just set it and leave it static.
  7. This has many great possible applications. The base skinned mesh can be also clustered or have additional deformation controls layered so that you can reshape/sculpt the silhouette of the mesh or produce fake muscle slidebuldge.
  8. For an added layer you can can directly transform the rebuilt surface as another layer of control over the effect.
  • I used surfaces that were drawn around the top of the shoulder , base of neck down over the shoulder muscle and also from shoulder down the back to help with clavicle deformations. This can be run down the belly of the character to help with skin compression when leaning forward and during twisting. At the hips running extracted surface helpers along the front and side of the leg to help with complex folding/creasing and other hip related problems makes life much easier since the low rez rebuilt surface stays evenly spaced you avoid deep pinching valleys in the mesh.
  • You can run the surfaces along the surface in the way that a muscle would lay or you can just fallow the basic from in a strait line in areas that are pinching like the crease at the shoulder/clav and the hip when you lift the leg strait up or out to the side in the splits, helps keep the skin from just pinching in..it lets the skin compress and stretch instead and it uses the skinning info all ready there to follow along so you want to get it as good as you can to start with and instead of helper joints with complex driving situations or pose spaced def you can use this as a helper surface instead.
  • Time saved 4 days trying for fixing issues with normal methods(cluster/helper joints/lattice/skin weights) vs. 2 hours with the Influence object rebuilt surfaces technique
Sample video showing curve layout and the difference between the base curve that matches the mesh and the rebuilt curve that is only like 5 points and how it is offset.