Unmanned aerial vehicles (UAVs) are being utilized in a range of applications such as firefighting, surveillance monitoring, law enforcement, security work, and aerial thermography. This field of technology has been gaining wide attention, however at times it is difficult to acquire video images of high quality because of poor video transmission. The German embedded systems specialist TeAx Technology UG, established in February 2013 by Stefan Thamke and Markus Ax, overcome this difficulty with their ThermalCapture hardware (Figure 1) and FLIR's Tau2 thermal core, which enable thermal video to be easily stored on the UAV and can be viewed and post-processed at a later date.
Figure 1. ThermalCapture is a custom designed hardware solution that allows the user to store RAW thermal video data directly on a USB memory stick, together with additional information.
Both Markus Ax and Stefan Thamke carried out years of research at the University of Siegen through different projects in the field of outdoor robotics. They have in-depth experience in the coordination of UAV swarms in real-time circumstances, and in controlling UAVs over Internet Protocol (IP) networks.
Stefan Thamke stated that many experiments were carried out on the thermal cameras used onboard the UAVs, especially the FLIR Tau2. However, it was observed that the transmission of video from the UAV to the ground wasn't always entirely successful. The digital data image could be degraded due to atmospheric and weather disturbances, and this would be displayed as missing links or stripes in an image. It was proposed that along with the video transmission, the presence of a local digital data storage on the UAV could be ideal. As a result, the video quality is not degraded as the raw data and the transmission can be post-processed later. The FLIR Tau2 thermal core provides a lightweight and compact storage solution, unlike any others on the market (Figure 2).
Figure 2. With this camera core, you have the image quality of a high-performance thermal imaging camera in a compact and lightweight format.
Capture Thermal Video and Store Locally
ThermalCapture is a custom-made hardware that enables the RAW data and additional information to be directly stored on a USB memory stick. This hardware can be suitably accommodated at the rear side of a FLIR Tau2 camera core and can be easily mounted with the camera into the existing holders. ThermalCapture is capable of enriching the raw data with additional data (Figure 3) such as the position and time acquired from the GPS.
Figure 3. ThermalCapture is able to enrich the raw data with additional information like position and time from GPS.
The FLIR Tau2 core, combined with the ThermalCapture hardware, provides a complete solution. This hardware is ideal for users who already have an FLIR Tau2 core integrated onto their UAV and are looking to expand the functionality with storage. The better image quality, low weight (<110 g) and the highly compact size enable the FLIR Tau2 core to be easily integrated into a UAV. In addition, the FLIR Tau2 has a wide range of lens options and resolutions. It provides a perfect solution for all types of budget.
The highly advanced radiometric option of the FLIR Tau2 cores is supported by ThermalCapture. This option enables temperature measurement to be carried out for each individual pixel in a picture. ThermalCapture has two operational modes, quite similar to operational modes of a normal camera: the video footage can be acquired either through an external trigger or through continuous recording.
Thermal Imaging Software
ThermoViewer, a software solution provided by TeAx Technology, is equally as important as the ThermalCapture hardware. After a flight, this software processes the recorded raw data acquired from the ThermalCapture module by reading the raw data from the USB memory stick, and converting it into color or black and white images (Figure 5).
Figure 5. The ThermoViewer software reads the raw data from the USB and converts it to black & white or color images.
To achieve fast results, users can use the auto-conversion feature. This enables the ThermoViewer software to determine the needed parameters for each dataset, and to save the outcome as a normal PNG image. A high-quality image can be obtained by finding the highest and lowest temperatures and then performing interpolation. Novice users may find it hard and time-consuming, however experts can opt to manually convert the parameters to acquire highly optimal results for each picture.
Enhanced Thermal Imaging Performance
UAV users are now able to dispose of the raw video date, enabling them to see and obtain more valuable information.
Stefan Thamke suggested that it is amazing what a user can obtain from raw data. Consider an instance when a soldering iron is viewed in an indoor scenario. If a thermal camera is used without setting the appropriate parameters, then the focus of the camera will likely be directed only on the hot iron, leaving the remaining area of the room black. However, when appropriate parameters are set on the raw data and when the accurate viewing range is selected, the rest of the room may appear again.
Even though this instance is a relatively theoretical one, it applies even for realistic industrial environments, where very hot, but less important things have to be blocked at times. Here, setting the appropriate parameters on the raw data helps. Similarly, using the raw data is highly advantageous during UAV inspections of solar panels.As certain types of solar panels reflect intensely, while others do not, the visibility of particular areas on the solar panels are impacted. The visibility of such areas can be enhanced by post-processing the raw data, after setting the appropriate parameters.
This information has been sourced, reviewed and adapted from materials provided by FLIR Cores and Components Group.
For more information on this source, please visit FLIR Cores and Components Group.