This video shows the basics of how SHAPES works in regards to auto corrective setup.
Maya: SHAPES 2
This page will show how to create corrective blend shapes for the body using SHAPES 2 . SHAPES 2.0 has a free PLE and can be bought for commercial use. SHAPES is by far the easiest way to do this workflow currently and uses mostly maya in built tools with a far better interface and worklow features.
It’s designed to highlight issues on a number of rigs. Due to the issue of gimbal lock, auto correctives can be more complx to setup than might first be expected.
Certain rigs will help make the correctives easier. For example a rig that supports solid no flip twisting. The “No flip” twist on shoulder and hip ball joints is not what’s thought of as the 180 degree twist problem. It’s rare for any body part to twist more that 180 degrees. Instead we need a rig that’s twist is measurable with reliable up vectors and won’t be prone to gimbal problems. For the shoulder the start of the twist should always point up as much as possible.
Also certain setups for spines and necks will make it difficult to create automatic correctives that are reliable in every situation. Additionally it can also be surprisingly difficult to get reliable hinge joint values out of elbows and knees in certain rigs that use constraints and the three chains for IK/FK swithcing, this is common in Maya rigs.
It’s also recommended that rigs that support ball jointed elbows should be locked to one axis. There are workarounds but since this page has more to do with setting up SHAPES 2 I’ll only briefly touch on these issues as they come up as many times they have to do with the rig rather than this methodology.
Lastly automatic joint setups can… and in some situations should be used in tandem with blend shape correctives. A good example of this is automatic halfway joints. I’ll be building some of those systems that can help greatly and post them here in the future. There are two types of automatic halfway joints I’ll be covering later. Hinge and Ball joints as the ball joint method adds extra complexity.
Hinge is only one axis of rotation (elbow knee). Ball allows for all (shoulder, upperthigh/hip). Usually hinge joints are used by creating Driven Key Drivers, ball joints often need weighted drivers (pose reader/cone readers) to get around gimbal rotation problems.
SHAPES 2 can be used in a huge variety of situations not only on the face and body, it’s useful in most blendshape workflows.
By Ingo Clemens over at www.Braverabbit.de SHAPES maximises the power of maya’s blendshape system. It’s a new approach to blendshapes that solves many traditional deformation issues, it’s extremely powerful and simple to use.
Contents (1:36 hrs)
1.1 – How Shapes Works
2.1 – Anim Finaling
3.1 – Driven Key (Hinges)
3.2 – Weight Drivers (ball joints)
4.1 – Mesh Topology
5.1 – In Betweens
6.1 – Elbow Multiple Shapes
6.2 – Rotational Problems
7.1 – Shoulder Twist/Elbow
8.1 – Shoulder Setup
We can setup full automated correctives, but on many and I’d say most jobs anim finalling is a far easier method where the animation is sculpt fixed after the animation’s completed.
Proper corrective workflow can be tedious, so in many cases this is a better option with less hassle.
Auto corrective workflows can be done in SHAPES with two methods
1. Driven Keys
2. Weighted Drivers
Most maya users will be familiar with driven keys and if not it’s best to have a basic understanding of these first, though SHAPES takes all the hassel out of the workflow.
Weighted Drivers are simply “pose space readers” sometimes refered to as “pose space deformers” or PSDs. they can also be named “cone readers”.
Weighted divers help us get around potential gimbal issues, but can be slightly slower and have some issues of their own.
Mesh topology can be critical when it comes to blendshape deformation workflows.
Maya has the ability to do in between blendshapes, here’s how to use that in SHAPES.
Elbows/Knees can be tricky because the blend covers a large angle range. So it’s often best to break them up into three or more blends.
There can also be issues on some rigs due to flipping which should be known about too.
Issues of multiple blends in elbows is made more difficult with the additional factor of shoulder and forearm twist. This is where you’ll need a solid twist setup on the rig.
The following briefly describes this issue with solutions.
Shoulders can be tricky, the following goes through a good shoulder workflow, breaking the weighted drivers into 90 degree angles.