Recently, in order to make proper use of the Yangtze River coastline, and improve the maintenance of the Yangtze River’s ecology and river safety, the Zhenjiang Municipal Government urgently needs high-resolution orthographic images of 500 meters range of Yangtze River, and integrates it as an image base map and water conservancy thematic information. . The project area starts from Jurong City Avenue river in the west to Xilaiqiao Town in Yangzhong City. The ground resolution requirement is 8 cm.
A drone with a wingspan of 2.5 meters rises slowly on the beach on the banks of the Yangtze River. This is a vertical takeoff and landing drone built specially for aerial surveying – MMC “Griflion M8”. This drone combines the advantages of multi-rotors and fixed wings: flexible take-off and landing, limited by the environment; fast flight speed, long battery life, can be equipped with high-definition cameras; also with RTK+PPK system, one button accurate take-off and landing, it meets the requirements of high-precision imaging.
Before taking off, the pilot has uploaded the meticulously planned route to the drone. According to the 8 cm resolution requested by the customer, the aerial surveying’s imaging overlap ratio is set to 75% of the heading, 70% of the sideways, and a total of 41 flights. After about an hour, with the benefits of the RTK centimeter positioning, the plane finally landed at the takeoff point accurately. After a simple equipment inspection and disassembly work, the pilot drove to the next takeoff point.
During the flight operation of the drone, there are often winds at level 6-7 and heavy rains. The MMC mapping team completed the 400-square-kilometer flight in just 15 days, acquiring more than 21,000 high-quality images at resolution of 42 million pixels. At last, the staff imported the data into the Pix4Dmapper for processing, and stitched all the scattered drone data into a continuous, standardized, measurable image map. It provides reliable information for the government to fully understand the development and utilization of the Yangtze River coastline.