Optical Detection and Evaluation of Lightning Discharges

Proc. 29th Intl. Conf. on Lightning Protection

The observation of lightning strikes by using various approved measurement and location systems is an important task in the field of the lightning research work. Still a lot of unknown phenomena and effects are under discussion belonging to the discharge itself and the striking point at ground.
A new approach for the detection and evaluation of the lightning discharge can be presented in this paper by using an optical measurement system, which can give another type of detailed information about the lightning activities, the lightning behaviour or the lightning location in an area under observation. The evaluation of the lightning channel in this research work is based on a photogram metric measurement process. Using two or more camera systems positioned at different view points it is possible to reconstruct the three dimensional location of points in the observed volume. In order to use digital cameras in a measurement system their internal parameters need to be determined in a calibration process. Additional the relative orientation of the cameras is required to triangulate points in the observed volume. This is done by using algorithms of the field of multiple view geometry. A final registration makes it possible to bring the reconstructed points into a global coordinate system. The lightning channel itself will be represented by a number of calculated points in the observed volume. Once the system is installed measurements can be obtained in a fully automatic way.
First results of artificial lightning strikes captured in the high voltage laboratory validate the feasibility of this optical measurement process with an achievable accuracy in the range of 1:200. Compared to conventional lightning observation systems this photogrammetric method gives a number of new information about the lightning strike within the limited observed area.