Efficient and accurate fitting of Active Appearance
Models (AAM) is a key requirement for many applications.
The most efficient fitting algorithm today is Inverse Compositional
Image Alignment (ICIA). While ICIA is extremely
fast, it is also known to have a small convergence radius.
Convergence is especially bad when training and testing
images differ strongly, as in multi-person AAMs. We describe
“forward” compositional image alignment in a consistent
framework which also incorporates methods previously
termed “inverse” compositional, and use it to develop
two novel fitting methods. The first method, Compositional
Gradient Descent (CoDe), is approximately four
times slower than ICIA, while having a convergence radius
which is even larger than that achievable by direct Quasi-
Newton descent. An intermediate convergence range with
the same speed as ICIA is achieved by LinCoDe, the second
new method. The success rate of the novel methods is 10 to
20 times higher ...