1) The document discusses a semantics-based approach to machine perception that uses semantic web technologies to derive abstractions from sensor data using background knowledge on the web.
2) It addresses three primary issues: annotation of sensor data, developing a semantic sensor web, and enabling semantic perception intelligence at the edge on resource-constrained devices.
3) The approach represents background knowledge and sensor observations using ontologies, and uses deductive and abductive reasoning over these representations to interpret sensor data at multiple levels of abstraction.