In the discussions above, we implicitly assumed that observation stations share common visual fields with each other. In monitoring geographically wide spread areas, however, such assumption does not hold always (Fig. 17).
Figure 17: Overlapping and non-overlapping visual fields.
In [14], we proposed a cooperative distributed object identification system to track multiple objects across a geographically wide spread area: pieces of partial object information observed by a group of observation stations without common visual fields are integrated into a bundle of object trajectories. To cope with large scale problems, we are extending the system by introducing a hierarchical organization among observation stations.
