Urban sensing systems: opportunistic or participatory?

The development of sensing systems for urban deployments is still in its infancy. An interesting unresolved issue is the precise role assumed by people within such systems. This issue has significant implications as to where the complexity and the main challenges in building urban sensing systems will reside. This issue will also impact the scale and diversity of applications that are able to be supported. We contrast two end-points of the spectrum of conscious human involvement, namely participatory sensing, and opportunistic sensing. We develop an evaluation model and argue that opportunistic sensing more easily supports larger scale applications and broader diversity within such applications. In this paper, we provide preliminary analysis which supports this conjecture, and outline techniques we are developing in support of opportunistic sensing systems.