TUM PLC & Helios
The hardware for the TUM weather protection enclosure and Helios setup is not available to buy off the shelf yet. Please contact us if you are interested in acquiring our hardware.
The TUM hardware used by MUCCnet has been described in Dietrich et al. 2021 (https://doi.org/10.5194/amt-14-1111-2021).
What does Helios do?
Helios evaluates the current sun state - whether direct or diffuse sunlight is present. EM27/SUN applications require direct sunlight for measurement data to be useful. Additionally, CamTracker will lose track of the sun with very diffuse light conditions and requires a restart.
The Helios hardware is made up of a transparent globe with black stripes glued to it and a translucent milky glass with a camera pointing upwards attached below.
Helios will periodically take images with that camera, process them, and evaluate shadow conditions. The processing will detect the lens circle and cut off the outer 10% of the radius - a lot of unwanted shadows can occur on the edges due to dirt from the outside. Finally, it will use a canny edge filter and count the pixels where "fast transitions between light and dark" can be found. If the pixel count is above a certain threshold (configurable), the sunlight conditions are categorized as "good".
Example images in bad conditions:
Example images in good conditions:
