An object detection system for a mobile machine is disclosed. The object detection system may have a first array of laser beam transmitters configured to generate a first plurality of grid lines on a ground surface, and a second array of laser beam transmitters configured to generate a second plurality of grid lines on the ground surface and produce a plurality of intersections with the first plurality of grid lines. The object detection system may also have a receiver configured to detect the plurality of intersections and generate a signal used to create an electronic terrain map based on the detection. At least one of the first and second arrays of laser beam transmitters may be selectively movable during operation to change a location of the plurality of intersections.