Environmental monitoring.
The idea of camouflaging pervasive sensing nodes as rocks comes from the application domain of environmental monitoring
and dates back to the PODS project [33] on the long-term study of rare and endangered species of plants in Hawaii National
Park, one of the early projects that explored environmental monitoring applications in the years 2000–03. In the first half
of the past decade, environmental monitoring quickly became one of the most popular application domains. In the field
of wildlife and habitat monitoring, pioneering contributions came from UC Berkeley’s Great Duck Island deployment [34]
and Princeton’s ZebraNet [35]. The Great Duck Island deployment relied on motes with sensor boards to study the nesting
habitat of the Leachs Storm Petrels on a small island off the coast of Maine and showcased the potential of sensor networks
as tool for unobtrusive monitoring. The ZebraNet deployment used GPS collars to track zebras in Kenya and leveraged delay
tolerant networking techniques to collect the data. In those same years, Harvard’s volcano monitoring project [14] showed
that sensor networks could be used to monitor hazardous phenomena at a fine-grained level of spatial resolution