One embodiment relates to an apparatus (102) for detecting an object in an environment, the apparatus comprising: a camera (208) controllable to switch from a first to a second mode to prepare the camera to capture an image; a processor (202), wherein the processor is arranged to receive motion detection data associated with a first monitoring region in said environment, and measured wave reflection data associated with a second monitoring region obtained by an active reflected wave detector (206), wherein the first monitoring region includes at least part of the second monitoring region and extends beyond the second monitoring region in at least one direction. In response to the processor detecting motion in the first monitoring region, the processor is configured to: activate the active reflected wave detector; determine whether a predetermined condition is met; if the condition is met, perform at least one operation related to camera image data.