I’ve worked on pipelines and tools for facial animation rigs for about 7 years now. In that time a lot of has been written about Facial Expressions and Ai. In this article I summarise the reference’s I find most useful for illustration, performance and character rigging.
Top of the list is Paul Ekman who has been researching the subject for over 50 years. His book ‘Unmasking the Face’ illustrates the seven universal understood emotions we reveal with our facial expressions.
Anger, Fear, Disgust, Contempt, Surprise, Sadness, and Happiness.
This research has been reinterpreted for many applications. The FACs system is an great way of breaking down facial expressions into it continuant parts. It helps us understand the key elements of facial expression and how we recognise them. It is a huge help in design morph target sets for 3d characters.
It has been used in psychology and also in art.
Books for illustrators and animators
Two great books for illustrators based on Paul Ekmans work are
The Artist’s Complete Guide to Facial Expression by Gary Faigin
Making comics by Scott McCloud
Both of these books describes the six key expressions for illustration as:
Anger, disgust, fear, sadness, surprise, and joy.
Gary Faigin’s book gathers together a wealth of anatomy, and illustration to create an excellent reference for the subject.
Scott McCloud (famous for his excellent book ‘understanding comics’) has a chapter on faces in his book ‘making comics’. He breaks each expression down into key features and illustrates them simply in a comic style. This has been implemented in a neat little flash app that allows you to blend between the emotions visually http://grimace-project.net/
Facial character rigs
An invaluable book on facial character rigging is: Stop Staring: Facial Modeling and Animation Done Right! by Jason Osipa. It was the foundation of much of the work I’ve done with Audiomotion though experience eventually led us to develop our own specialised facial rig.
A related area of study is the so called big five. My friend Richard Evans (lead AI programmer on the Sims, Black and White etc) suggested this as being helpful in the design of emotions for Ai characters. They are significant in defining a persons behaviour rather than their expression.
The exact labels chosen for each dimension vary. Here are the labels suggested by John, Naumann, and Soto at Berkeley
There are five categories are labelled by letters. An OCEAN of personality dimensions.
O for openness, originality, or open-mindedness.
C for conscientiousness, control, or constraint.
E for extroversion energy, or enthusiasm.
A for agreeableness, altruism, or affection.
N for neuroticism, negative affectivity, or nervousness.