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 (Z) each corresponding to a respective portion of the representation, each zone (Z) 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 (Z) each corresponding to a respective portion of the representation of the scene, each zone (Z) 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 (Z) of the differential grid (ΔG) in the active state only if the corresponding zone (Z) of the current occupation grid (G cur ) is in the occupied state and if the corresponding zone (Z) 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 (Z) 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 (Z) each corresponding to a respective portion of the representation, each zone (Z) 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 (Z) each corresponding to a respective portion of the representation of the scene, each zone (Z) 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 (Z) of the differential grid (ΔG) in the active state only if the corresponding zone (Z) of the current occupation grid (G cur ) is in the occupied state and if the corresponding zone (Z) 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 (Z) of the differential grid (ΔG) is in the active state. <EOS>