Integration of fuzzy spatial information in tracking based on particle filtering.

In this paper, we propose a novel method to introduce spatial information in particle filters. This information may be expressed as spatial relations (orientation, distance, etc.), velocity, scaling, or shape information. Spatial information is modeled in a generic fuzzy-set framework. The fuzzy models are then introduced in the particle filter and automatically define transition and prior spatial distributions. We also propose an efficient importance distribution to produce relevant particles, which is dedicated to the proposed fuzzy framework. The fuzzy modeling provides flexibility both in the semantics of information and in the transitions from one instant to another one. This allows one to take into account situations where a tracked object changes its direction in a quite abrupt way and where poor prior information on dynamics is available, as demonstrated on synthetic data. As an illustration, two tests on real video sequences are performed in this paper. The first one concerns a classical tracking problem and shows that our approach efficiently tracks objects with complex and unknown dynamics, outperforming classical filtering techniques while using only a small number of particles. In the second experiment, we show the flexibility of our approach for modeling: Fuzzy shapes are modeled in a generic way and allow the tracking of objects with changing shape.