An example method includes determining first classification rule(s) based on first data that classifies pixel groups of first reference image(s) as types of objects. The first reference image(s) are captured by a first sensor. The method further includes determining second classification rule(s) based on second data that classifies pixel groups of second reference image(s) as types of objects. The second reference image(s) are captured by a second sensor. The method includes classifying, as respective first objects, pixel group(s) of a first image of a scene based on the first classification rule(s). The method includes classifying, as respective second objects, pixel group(s) of a second image of the scene based on the second classification rule(s). The method further includes determining whether a change occurred in the scene based on the object classification of the first image(s) and the second image(s).