Thermal imaging & vision systems

SimultAneouS oPticAl And thermAl trAcking of AircrAft And droneS

Specialised Imaging has repor ted on how its Lightweight Optical Motion Analysis (LOMA) system has been used to optically track an aircraft for several kilometres while simultaneously capturing the thermal signature of the aircraft over the same distance. Robustly constructed, the LOMA system accommodates large multiple

camera payloads enabling high precision optical tracking of fast moving aircraft, drones or projectiles even in environments subject to vibration, electromagnetic radiation or extremes in temperature and humidity. Fitted with a a Basler high resolution optical camera with a 50mm Nikon

lens and a FLIR X8500SC thermal imaging camera with 200mm lens, the LOMA system was used to track approximately 15km of the plane flight. In poor weather or night time conditions the data from the thermal camera would be the preferred way to track the target. Fast to set-up and easy to operate, the LOMA tracking mount

provides a high level of camera positional accuracy and operational flexibility. Using independent motors, LOMA system users can control camera elevation (-20° to + 190°) and provide unlimited azimuth rotation using slip ring technology. Precision motor controls

ensure smooth auto track functions to capture distant fast moving objects with an angular accuracy of ± 0.002°. In this field trial the LOMA system used

a “hot spot” tracking algorithm focused on the aircraft nose. However the software has an offset function that allows the centre of the field-of-view to be moved away from the specific area being tracked. This feature is par ticularly useful when looking at rocket plumes which are at the rear of the projectile but the area of interest is the front or mid section. Fur ther along the flight of the tracked object the offset can be reduced or removed and the tracking point changed from the front to the centre as the target changes orientation. AutomAtic for A Perfect imAge

Different measurement scenarios often require temperature measurement ranges or integration times that vary from the initial factory calibration and are individually adjusted. Usually the calibration is invalid as a result of such adjustments and the thermographic camera no longer provides any accurate

temperature measurements. Users of the InfraTec’s thermographic camera series ImageIR now have an alternative. Thanks to the HighSense function, the measurement accuracy of their cameras is also preserved when integration times or the measurement ranges are changed. With maximum flexibility they also save costs, for example, by avoiding additional application-specific special calibrations. The development enhances the existing factory calibration of the

thermographic camera. It enables the possibility of setting up individual customised temperature measurement ranges. Users can apply their specific settings in different ways. The first way allows for the selection of a desired integration time. After

entering the integration time via the intuitive software interface, the resulting temperature measurement range is calculated automatically and can be used for accurate measurements. At the same time, the selected lens as well as neutral density filters or spectral filters are also taken into account. The second way addresses the issue of the temperature measurement range. This can be specified by defining an upper and lower limit. Afterwards, the


appropriate integration time is calculated again to achieve the optimum signal-to- noise ratio and stored as setting parameter for the planned measurement task. Depending on whether a particularly high thermal sensitivity or the maximum possible frame rate is paramount – with the appropriate adjustment of integration times and the resultant automatically generated temperature measurement ranges the HighSense feature offers considerably more flexibility in order to optimally fulfil the measuring tasks at hand. In addition, the calibration of individual sub-frames is no longer necessary.

The adjustment of the calibration data, which applies to these frames, takes place automatically as well. On this basis, accurate temperature measurement values are also provided for the corresponding window modes. Thus, the choice of the temperature measurement range as well as the integration time does not depend on whether the image should result in full-frame mode or in sub-frame mode, which can be used to achieve a higher frame rate. Thanks to HighSense, users of the ImageIR now have the option to set up

individual measurement ranges based on the factory calibration, which are best suited to the task at hand. The software also offers the possibility of storing a multitude of such ranges in a clearly visible way. Individually named and permanently stored, the user can access these settings quickly. The same holds true when it comes to changing, renaming and deleting the profiles. HighSense is available for various camera models of the ImageIR series.

Systems that have already been delivered can be enhanced by this function.

April 2019 Instrumentation Monthly

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