Electronic device for monitoring a scene via a set of N electronic sensor(s), where N is an integer greater than or equal to 1, the device being intended to be connected to the set of N sensor(s) and comprising: - an acquisition module configured to acquire, from the set of N sensor(s), at least one representation of the scene, - a conversion module configured to convert each acquired representation into a respective occupation grid (G cur, G ref), each occupation grid (G cur, G ref) comprising a plurality of zones each corresponding to a respective portion of the representation, each zone of the occupation grid being in an occupied state if said portion contains an object and in an unoccupied state if not, - a calculation module configured to calculate a differential grid (ΔG) corresponding to a difference between a current occupation grid (G cur) and a reference occupation grid (G ref), the differential grid (ΔG) comprising a plurality of zones each corresponding to a respective portion of the representation of the scene, each zone of the differential grid (ΔG) being in an active state or an inactive state; by ignoring each zone of the reference occupation grid (G ref) which is in the occupied state and for which the corresponding zone of the current occupation grid (G cur) is in the unoccupied state, the calculation module is configured to calculate a respective zone of the differential grid (ΔG) in the active state only if the corresponding zone of the current occupation grid (G cur) is in the occupied state and if the corresponding zone of the reference occupation grid (G ref) is in the unoccupied state, and - a detection module configured to detect a change in the scene from the calculated differential grid (ΔG), the detection module being configured to detect an appearance of an object in the scene when a corresponding zone of the differential grid (ΔG) is in the active state. - an acquisition module configured to acquire, from the set of N sensor(s), at least one representation of the scene, - a conversion module configured to convert each acquired representation into a respective occupation grid (G cur, G ref), each occupation grid (G cur, G ref) comprising a plurality of zones each corresponding to a respective portion of the representation, each zone of the occupation grid being in an occupied state if said portion contains an object and in an unoccupied state if not, - a calculation module configured to calculate a differential grid (ΔG) corresponding to a difference between a current occupation grid (G cur) and a reference occupation grid (G ref), the differential grid (ΔG) comprising a plurality of zones each corresponding to a respective portion of the representation of the scene, each zone of the differential grid (ΔG) being in an active state or an inactive state; by ignoring each zone of the reference occupation grid (G ref) which is in the occupied state and for which the corresponding zone of the current occupation grid (G cur) is in the unoccupied state, the calculation module is configured to calculate a respective zone of the differential grid (ΔG) in the active state only if the corresponding zone of the current occupation grid (G cur) is in the occupied state and if the corresponding zone of the reference occupation grid (G ref) is in the unoccupied state, and - a detection module configured to detect a change in the scene from the calculated differential grid (ΔG), the detection module being configured to detect an appearance of an object in the scene when a corresponding zone of the differential grid (ΔG) is in the active state.