back muscles

Animal Anatomy Reference

Canine/ Human

Horse/ Human

Bird/ Human

Human Anatomy Reference

Back

Torso

Leg

Super Hands!

Really useful resource I found on hands amassed from Disney footage i found . The drawings delineate all the various poses the hands are capable of pulling and reflects the wide ranges of motion that can be achieved. This is very useful reference material and will come in handy when testing rigs out and will also help to determine appropraite set driven keys on common poses.

Arm Orientation Selection

This set-up allows the animator to control which axis the arm should follow when the torso bends. I did this by using four locators that have an orient constrain influence at the locator at the top of the arm. When the torso joints rotate, the parented locators will rotate accordingly (or not as the case may be). The upp. arm joint will then follow the locator with the weight value of 1.

I also set up an orient attribute on the upp arm - in a rig this would have been set up on the controller - so the animator can dial in the orient axis they wish to follow. Useful for rotating the body whilst maintaining the arms orientation.

Orient Joint (Demystified)

I for one have always struggled to understand how this dialogue box works, and when I finally do figure it out, I forget how it works agian.

So to concrete its functionality in user friendly history, here is the instruction manual:

1.) The radio buttons have all the possible sequences of axis to choose from.
2.) The first axis in the sequence will be the one that points down the joint chain (in most cases (apart from mocap which uses the Y axis) this will be the X axis).

3.) The second axis will point in whichever direction you have set the "Second axis world orientation" option to. For example, if it's set to -y, the second axis in the sequence will point in the world orientation of -y.

4.) So the third axis in the sequence will trail along behind and point in the appropriate direction.

This little box has always been one of lifes little mysteries, I hope this settles our differences and we can live in harmony together for ever more.

Skeletal Reference

Walking Human skeleton, as you can see from this image the pelvis connects the back to the hips. The back rotates from the upper pelvis and the hips from the lower, so there are two areas of rotation.

The neck region works independantly of the head and can transform/rotate while the back stays still. Two seperate spline ik's could be used to achieve this locking motion.

Spine Reference

Diagram showing the spine's position in relation to the torso. As you can see it is placement is nearer the right hand side, and continues to the base of the skull, meaning the neck region has just as much articulation as the spine and should be reflected within the rig.

The Lordis areas highlight the positions of motion demonstrated by the yoga instructor and should therefore be manouverable in the rig.




 
 
 
 
 
 
 
However...
 
 

According to rigging guru Jason Schleifer (author of highly acclaimed series of tutorials called "Animator Friendly Rigging"), the spine joint chain should be laid out in a straight line so their rotational axis remain parallel to each other, so when the character twists their body the deformations look realistic.

 
 

Anatomy Reference

Joint placement reference material. This is a good example because all the motion motion is done slowly and the camera angle is almost orthographic and she achieves a good broad range of motion.

I'm particularly interested in the spine area, both top and bottom, where it meets pelvis and neck.

Pivots

straight up

The pivot location for the pelvis and hips, the outer circle demonstrates the motion of the top of the legs as she bends over.

The torso rotates on this axis.







Bent over

The position of the pivot remains the same as she hasn't translated her axis in any direction, just rotated by around 90°, this illustrates the pivot is in the correct position.







Spine Mobility

She also hyper extends the spine (demonstrating how not to do the exercise) which show the backs manouverability in the lower region as the second joint translates out to form an arch shape.

Ribbon Spine

Another variation of the spine, this one utilises the v position on a nurbs curve (the ribbon) to evaluate the interpolation between the skinning joints, whose up axis corresponds to the surface normal via a hair follicle system. 

Sounds complicated, but the real beauty of this is setup is once it's connected up, Maya will make all the necessary calculations to generate perfect fall off. 

Advantages over spinewave rig:

1. You have independant twist control from the centre joint, something which eludes the standard squetchy spine (unless you implement a quarternion system).
2. With the standard squetch spline the end joint can pop beyond the top controller, which the animator has no control over. The ribbon spine remains rooted at each end giving a nice ik action. 
3. Weights can be adjusted on the falloff so the rigger/animator has a better control of how the falloff occurs down the spine as it twists. With a standard spline Ik there is just the one curve which rotates on it's own up axis, this works ok but with the ribbon there are two curves on the u axis and its interpolation is calculated between them  (thats the beauty of Nurbs!), these weights can be easily adjusted in the component editor. 

 Disadvantages are:

1. Difficult to come up with any, but the quarternion setup would be better suited for circumstances that needs tight control. For instance, if I was rigging a tentacle or snake, i would opt a spine type setup. The ribbon spine would not be able to create "S" shaped curves without applying more joints down the patch and locators.  It's certainly achievable but not as simple as the quarternion setup.

Besides this, a really nice organic set-up that will give smooth results.  

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Ribbon Hypergraph

Hypergraph and the spine itself...

The setup consists of a nurbs patch, which has a hair follicle attached to each section (to aquire the normal data). A joint is then parented to each follicle and have their translates zeroed (to move them into position)- these will be skinned to the character.

Another joint chain is created, this will be an fk chain and will be skinned to the patch to control its transformations. Three locators are then created, two parented to one. The daddy locator will be the position locator, the middle the aim and the third the up locator which is scaled down for visual purposes.

The locators are duplicated twice (total of nine locators) and are renamed respectively for middle and bottom. The mid pos locator is point constrained to the top and bottom locators. When one is moved the mid loc. will average its position between the two, giving the stretch control.

The aim loc. is then aim constrained at its opposite pos. loc. so it follows when translated. The mid loc. is aim constrained to the top pos loc. The up locs. are used for the up vectors in the aim constraint (for the twist action). The second joint chain is parented to it's corresponding aim constraint (not pos, otherwise it won't inherit the aim aspect).

The second joint chain is skinned to the patch whic drives its movement. Now you can edit the weights on the cv's to achiece the desired twist and transform interpolation - you choose, you decide!

voila, a ribbon spine!

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Demonstration



Just a demo showing its squetch and twist capabilities. At the moment it's acting on the nurbs surface patch, so just imagine it having that effect on the skinned geo.

Divine Spine

Found yet another option for spine rigging online known as "The Divine Spine". I've had a read through it and it appears it's divinity comes under immediate question because it is infact a cross breed (or a mongrel) of the Isner and the Ribbon spine's (some may argue its a hybrid).


The initial setup resembles a spinewave rig - dense joint chain, spline ik, arc len node connected to a multiply divide node to calculate the stretch. Then another joint chain - with fewer links placed in the areas where deformation should occur is created, that is snapped to the spline. The spline is then skinned to the new joint chain, which now controls the initial joint chain, which in turn calculates the interpolation.

This is similar to the ribbon spine - when you examine its attributes is very similar to a spline Ik, it just uses a nurbs patch to give you the interpolation rather than the spline of the ik handle. 

But the Divine spine rig resembles a qarternion spine setup the best and could probably be utilised in the arm setup to achieve a nice twisting action that avoids candy wrapping .

Divine Diagram

I concocted this beautiful illustration to represent what's going on in the mongrel spine. The top Fk chain (the daddy chain) is controlled by the animator. This chain is skinned to the ik splines cv curve and controls its movement (the spline will create the interpolation down the chain). The spline chain is connected to a duplicate chain (little brother) which has SC IK handles connecting them. Each little brother joint has a locator which is connected to the ik's via a pole vector. The spine can be twisted at these points down the chain giving more articulation than if you used the spline ik's twist/advanced twist controls.

Arm Rig - Candy Wrapping

Arm Rig 1

Nice technique for maintaining volume when the arm is rotated in X (in this instance). Gives a smoother falloff between sections of the arm. The video below goes into greater deatail the procedure to create this arm rig.

Arm Rig 2

This video explains the technique to achieve the results featured in the above video. I have seen this a few times before, notably in Jason Schleifer's "Animator friendly rigging" series (well worth a watch!). The arm setup consists of two joint chains. The first is a simple chain that controls rotations, the second is the skinning chain which controls the falloff when the arm is twisted. To do this a multiply divide node is created and its input 1x is hooked up to the first joint chains twist rotation (in this occasion it's the Z axis). The value is then divided by 4 (or multiplied by 0.25 - same difference) and applied to the corresponding joints on the second chain. This is possibly how that nice falloff was achieved in the one eyed footballer rig that featured in  Edoardo Pili's impressive reel.

Character Rig Reel

Demo reel from a guy known as ArtOfJoelBeaudet on Youtube. Quite a simple rig, nice jiggle on the belly and face and some good features such as squash and stretch in the limbs and IK/FK switch. Set driven keys used to control the foot articulation (toetap, toelift, twist etc) and a bit of squash and stretch in the stomach.

Drunk Love


Another very short from the Joel Beaudet - this time the animation is hand drawn and gives great reference to the types of motion the character needs to achieve. Although its very it shows really nice drawing ability and the character pulls some some really nice exagerated poses.

Animation short by Julien Bocabeille, François-Xavier, Olivier Delabarre, Emud Mokhberi, Thierry Marchand, Quentin Marmier (from college "Gobelins L’Ecole de L’Image") and featured on the EA Sports website in an article called "Which are the best Animation courses in Europe?".

Really like the narrative - vey simple, but draws emotion from the viewer immediatelty, and brings you into the story quickly and simply.

From a rigging perspective, there's quite a bit going on. The Octopuses for example pose an ik challenge - probably overcome using a spline IK, with great emphasis on the twist control (which may be achieved using the locator technique illustrated in the "Awesome Spine" video).

Lots of "squetch" setup in the tentacles - gives them a rubbery feel, nice deformation and volume control - makes the stresses in the material seem believable (looks like they may snap when he/she's clinging on to the back of the van) and enhances secondary animation.

Octopuses walk cycle - octopuses don't walk naturally, so reference material would have to be sourced from less obvious resources, and then figured out by the animator to give the sense of urgency and anticipation. The van's engine enhances the tension - there may be hope for the octopus. This is a rescue story, and the stakes are raised from the moment the octopus is snatched.

Like the prop and set design, validates the story and gives it better flow - tropical environment, loads of outdoor swimming pools that are instrumental in the escape. Also using the Octopuses ink jet to escape the bipeds clutches.

Biped character has a straight forward riggig set-up, and what is apparent is the necessity to be able to lock limbs down to props. When the bipedial character is leaning out the vans window, he's clinging on to the roof. The animator will have a control that is parented to a spot on the van and will adopt its translates, but leave the rest of the rig free to animate.

Arachnid Rig

Nice arachnid rig, appears to do everything it should, but its control curves could do with being labelled a little more clearly. If you examine he setup there's a lot of non-discript circles that don't connotate their function.


I like the creatures folding mechanism, which operates nicely on a GUI slide, but i think the GUI window takes up precious screen space - some of the controllers are a bit bigger than they need to be.


Apart from that, theres obviously a lot of thought gone into the actual mechnanisms of the creature that woks well.

Spine Rig setup

"awesome spine" fonund on:


http://faithofthefallen.wordpress.com/awesome-spine/


Very similar to the Jason Schliefer tutorial - IK spline setup, with two skinning joints either side and a simple stretch mechanism implemented. In this example the rigger has duplicated the joint chain and connected each joint with ik handles. The handles ten parented to the spline joints so they follow the spline.


This twist mechanism implements a locator for each joint, connected to the joints using a multiply divide node, to achieve greater twist articulation control. In the Schliefer tutorial he uses the advanced twist controls implemented in the IK handle - seems to work fine, but gives you a uniform result. The ribbon spine's twist attribute can be adjusted by allocating different weight influence to nurbs vertex, so comes somewhere in between.


What is good about the Schliefer spine is the ability to control the volume of the distortion at different points down the back, using an animation curve. This provides good characterisation control for the animator and certainly help the shot look more interesting.

Eduardo Pili

TD showreel from Eduardo Pili, by the look of his impressive resume seems like he's been around a bit. Loads of things here to consider, the opening "quarternian" spine setup being notably impressive.

Looks like an "Isnerspine" setup which accomodates squash and stretch parametres by either adding an expression telling the joints scaleX value to adjust accordng to the curve length of the spline IK (by creating an Arc Len node).

Begins with a MEL window I assume Eduardo's scripted himself, that automates the spine rigging process - very handy because with two clicks of a button the spine is set up with squash and stretch parameters. Where this could be developed further is to add different spine setups to the script - perhaps a ribbon spine button, an Isner Spine button, a simple Spinewave rig, a Spline rig without stretch etc.


Notice the extra squash and stretch articulation achieved on the spine setup, this is called a "quarternion" spine, and in this instance uses widgets to control the volume in seperate area's. Very clever, and is done by creating a keyframe cache node (createNode frameCache). This node gathers numerical information from the timeline, so if you create an animation curve you can increase and decease the point position, which will increase the squash and stretch for that particular joint. The animator now doesn't have to go into the expression editor, they can simply alter the points on a curve - loads more interactve, intuitive and quicker to manipulate.

Good twist control - probably uses the advanced IK twist controls