What is the current condition of crops in a large agricultural area, how is the water quality in selected lakes and rivers and what is concealed under the earth's surface?
To find comprehensive answers to these questions, the Fraunhofer Application Center for Multimodal and Airborne Sensors AMLS, which was established jointly by Fraunhofer FHR and the University of Koblenz, develops flying sensor platforms on the basis of a gyrocopter to carry out cost-effective surface surveillance from the air.
The problem to date is that individual measurement techniques on their own are not capable of meeting all the requirements of this complex undertaking and can therefore not offer sufficient quality or require special techniques with are extremely expensive.
The scientists at AMLS therefore combine the advantages of different sensors such as radar and optical sensors and combine these to create an integrated system that also includes the appropriate evaluation software. In this way, high-precision measurement results from remote airborne surveillance in civilian application areas can be achieved through the utilisation of comparatively low-cost components.
Precision farming and nature conservation with PanTIR and Snapshot Imager
Thermal image maps of extensive agricultural and forested lands can provide important information about the condition and water requirements of the plants in specific land sections. Cameras in the long-wave infrared range (LWIR) are capable of delivering thermal images with a sufficient level of detail. Unfortunately, the spatial resolution capacity of these cameras is too low to precisely allocate the aerial images to a specific region during subsequent processing on a computer. This, however, is extremely important, inter alia, for the efficient planning of the resource-friendly irrigation of arable regions in precision farming. The airborne dual-camera system PanTIR from AMLS therefore combines a LWIR camera for the detection of emitted heat with a high-resolution panchromatic camera for spatial information. Together they deliver precise georeferencing and mosaiking of the images to allow thermal imaging of larger areas. PanTIR is presently being used within the framework of a hydrology project and further applications, e.g. in agriculture and industry or supply line monitoring, are currently being prepared.
The hyperspectral system Snapshot Imager, which draws conclusions about the three-dimensional surface topography and the condition of the plants on the basis of different spectral data - including radar -, works in a similar manner. In contrast to the conventional spectral line scanners, the new hyperspectral camera, which is used with other sensors, allows the direct spectral acquisition of two-dimensional areas with a single photo. With this technique, the time-consuming task of piecing together the single lines of the scanner is no longer necessary with the result that complex and expensive position sensors (IMU) are not needed on board the gyrocopter. Repeated flights over renaturation areas provide, for example, information on the success of the measures or an early warning of any undesirable developments. The system is also being tested in South Africa on agricultural land extending over several hundred hectares in cooperation with a partner who operates in the area of airborne, geomagnetic exploration.
Airborne landmine detection in Cambodia
Landmines and unexploded ammunition from the civil war still pose a big problem in Cambodia. Several hundred people lose their lives every year and the inability to access other regions of the country has a massive impact on the country's economic development.
In cooperation with aid organisations and mine clearance teams in Cambodia, AMLS is currently using its multispectral sensors to simplify the detection of landmines.
Over time, the explosive material in old landmines contaminates the soil and has a negative impact on the metabolism of the local plants. They therefore reflect sunlight differently than healthy neighbouring plants and this is detected by the multispectral sensors. The scientists at AMLS mount their multispectral sensors on an ultralight trike which is guided through the affected areas by a local pilot. In this case, the trike is a motorised hang glider with fabric dragon-like wings. The evaluation software for the image data is installed on a high performance, on-site workstation with the result that the researchers can provide the clearance team with georeferenced maps which contain important information for their work.
Within the framework of the pilot project, the team refined the sensors for this special application so that the results and experience gathered in Cambodia can be transferred to other countries and regions and used to provide valuable assistance in the clearance of landmines.