The paradigm of perceptual fusion provides robust solutions to computer vis
ion problems. By combining the outputs of multiple vision modules, the assu
mptions and constraints of each module are factored out to result in a more
robust system overall. The integration of different modules can be regarde
d as a form of data fusion. To this end, we propose a framework for fusing
different information sources through estimation of covariance from observa
tions. The framework is demonstrated in a face and 3D pose tracking system
that fuses similarity-to-prototypes measures and skin colour to track head
pose and face position. The use of data fusion through covariance introduce
s constraints that allow the tracker to robustly estimate head pose and tra
ck face position simultaneously. (C) 2001 Pattern Recognition Society. Publ
ished by Elsevier Science Ltd. All rights reserved.