Heavy rain and storms resulting in flooding have increased significantly in recent years. When large quantities of rain fall in very short periods of time, affected areas are often inaccessible. Real-time data and images from the air, combined where possible with sensor data on the condition of the ground, provide emergency responders with valuable information and allow them to intervene where it is most needed.

High-resolution aerial images for rapid assistance

A Manta camera from Allied Vision on board the ‘Hugin’ drone delivers images from the air and serves as the drone’s eye. The camera is equipped with a sensor with EXview HAD II technology and a resolution of 9.2 megapixels. The sensor distinguishes itself with outstanding image quality and high resolution, which allows ground objects to be inspected in fine-grained detail. Further crucial criteria for the choice of the camera were the availability of an Ethernet connection, as well as the global shutter sensor technology.

The Manta camera combines high resolution with low weight, factors that were important for the system’s developers. Hugin should carry as little additional weight as possible, to minimise the interference on the operation time. During the flight, individual images are recorded from altitudes of usually 100 metres, depending on the application. All obtained images are then processed in order to generate a continuous overview of the entire application area. Due to the camera’s automatic exposure adjustment functionality, even changing light conditions are manageable. Since comprehensive image preprocessing (i.e., image optimisation, light correction, white balance, colour correction) takes place within the camera, information-rich two-dimensional images are transmitted to the base station, located on the ground. In addition, a self-developed local communication network is used, which enables targeted information exchange, based upon different communication technologies. During catastrophic events, emergency responders can evaluate the situation better and more quickly with the aid of these images.

Successful tests in practice

Sewage disposal company Stadtentwässerung Braunschweig GmbH was confronted with serious flooding of the river Oker and urgently needed information on current water levels. They requested help from the Braunschweig TU. The area was monitored and documented with a variety of aerial images. The company thus not only gained knowledge about how the flooding had spread, but was also able to establish whether protective measures undertaken during earlier floods were successfully applied.

In another application case, the Braunschweig TU research team successfully tested Hugin in the field of coastal protection. On the East Frisian island of Langeoog in the North Sea, aerial photographs of dunes and dykes were taken. An item that attracted particular attention was a beach replenishment that was taking place at that time. Numerous aerial images were made of the location that clearly demonstrated to local coastal protection authorities just how close the tide came to the dunes in the still unfinished area of the beach replenishment and, at the same time, how far removed the surge was from the dunes when the beach level had been raised with additional sand.

The Braunschweig TU engineers are already considering other applications. Thus, the drone can be equipped with a thermal imaging camera, for example, in order to find injured persons in the dark.