DIGITAL AIR PHOTO PROCESSING FOR MAPPING OF COPPER ROOF DISTRIBUTION AND ESTIMATION OF RELATED COPPER POLLUTION
Emission of metals in the urban environment is a growing concern throughout the world. In order to identify metal emissions sources in the Stockholm metropolitan region, a method for detailed mapping of roof coatings and other urban land covers has been developed conducted. High accuracy area calculation of copper roof coatings based on scanned aerial photography was used. The geometric resolution of the digital photographs was 0.4 metre. Image layers with identified copper roof objects were merged with a digital elevation model of 1 metre geometric resolution. The slope gradient for each roof was calculated in order to account for slope in the calculation of roof areas. In total, 622,590 m2 of copper roofs were accounted, of which 176,845 m2 and 447,745 m2 represent new and patinated copper respectively. The number of copper roofs larger than 1,000 m2 was 142. Applying corrosion and runoff rates on these figures, a yearly Cu flux of approximately 1,200 kg in Stockholm may be derived from copper coated building.