Topography modification system by the confirmation for the reference point's location and geospatial data

PURPOSE: An image drawing system using a digital aerial image in which position measuring units placed outside of a real topographic object send and receive ultrasonic waves to each other to check mutual positioning is provided to exclude communications with a GPS(Global Positioning System) satellite in the process of checking position measuring units with each other, thereby drawing an exact image of a topographic object with a minimized amount of errors even in an urban area. CONSTITUTION: An image drawing system using a digital aerial image includes position measuring units(100). The position measuring units are located in each reference point of a topographic object. By sending and receiving the fixed intensity of ultrasonic waves to each other, mutual positioning is checked. The position measuring unit has a column shape which is easy for standing the same near the topographic object and includes a supporter(110); a head(120) on the top of the supporter; and a rotary ball(130) settled on the top of the head. The supporter, the head, and the rotary ball hold and protect an ultrasonic wave receiver, an ultrasonic wave sender, and electronic equipment.