  The strategic behaviour of pedestrians is largely determined by how they
perceive and react to neighbouring people. This issue is addressed in this
paper by a model which combines, in a time and space-dependent way, discrete
and continuous effects of pedestrian interactions. Numerical simulations and
qualitative analysis suggest that human perception, and its impact on crowd
dynamics, can be effectively modelled as a multiscale process based on a dual
microscopic/macroscopic representation of groups of agents.
