A method of detecting presence and location uses sensor data received from a plurality of thermopiles, each thermopile having a different field of view. In response to detecting a change in the sensor data, stored background values for each field of view are accessed and then the location of a body (e.g. a human or animal)is determined based on differences between the sensor data and sensor values predicted using a forward model and the stored background values for each field of view. Having determined the location, the stored background values are updated based on differences between the sensor data and the predicted sensor values for a body at the determined location.