TIP: tentacle rigs

UPDATE: This post is one of the most accessed on the blog. I wanted to add a link for people to a Maya tentacle rig tutorial that Joe Harkins did for Computer Arts. There is a PDF and sample files to download.

click for demo movie

I find lots of posts on people wanting to know how to rig up a tentacle and while there are some ways that can work very well, some can get very complicated quickly both for the TD and the Animator.

Depending on the needs of the shot, I am posting a file and a few pictures and videos of some simple but very solid tentacle rigs that I hope help people out.

1. Basic idea- FK Tentacle with geo skinned to it (animated as offsets from IK rig)
   
2. FK joints parented under spline ik animation skeleton FK tip extends out past IK ctrl for grabbing or curl/drag etc.
   
3. IK rig is a spline IK that gives you fast poseing and animation then FK offsets let you overlap and add noise in to the key poses created from the spline ik anim. Helps keep the keyframes for the poses and timeing clean because they stay on the IK.

How you interface the controls is really up to you and the animators. In the Maya example I just used selection handles because it was a quick file for demo, in the Max file it has control objects to animate with and was used by several people. This rig was used where I needed lots of control over timing and poses for the game level, but I wanted to be able to layer in extra movement with out breaking game play, and this rig allowed for that.

DOWNLOAD: Maya and Max Tentacle Examples


Here is an example of the max tentacle rig in action

Link: Wrist twist for animators and file referenceing

My friend Kiel Figgins has posted a detailed writeup on wrist twist and the pros of keeping it simple. Always good advice.

http://www.3dfiggins.com/writeups/forearmTwist/

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He also has a nice explination on file referencing and useing it to your productions advantage. Check it out.

http://www.3dfiggins.com/writeups/mayaReference/

Enjoy.
Brad

LINK: Dog leg rig and others - inspired by our inspired rigging book

I love finding links to people getting use or being inspired by our rigging book.

Here is a nice tutorial on useing the Maya spring IK with an automatic lower leg flex control.

"Dog Hind Leg Tutorial
By, Tyler Thornock

This tutorial will help you setup a dog/animal's hind leg with a single control to make it easier for the animator to move. This basically artificially sets up a spring ik. So if you have Maya 7, you may want to use it, though this setup does give you more control in the end. This setup may be confusing for some, but the stuff you learn can be applied to many other areas.

Well, the first part of this tutorial is "borrowed" from the Inspired 3D Advanced Rigging and Deformations book, however the book does not setup the rotation of the second part of the leg to be driven automatically which is a pain because the animator would have to rotate it appropriately every time they move the leg. With this setup, the animator can control the rotation or leave it automatic, unlike using a spring ik."

http://www.charactersetup.com/tutorial_dogleg.html


And here is another site with a spine rig tutorial, a reader of the book, taking ideas from it and expanding on them and then sharing it with the world. I just wanted to share the links to their sites and say thank you for giving back to the community.

"
By
David True

Maya Stretchy Spine

The objective of this tutorial is to create a Spine Chain that will stretch and Give you warning if stretch too far or Squash too much."

http://www.darksuit.com/tutorials/StretchSpine.html

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.

Examples:

• 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.