Harald U. Frey’s research interests in space physics concentrate on the connection between the outer magnetosphere and the ionosphere of Earth established by plasma processes in the upper atmosphere and ionosphere. As these processes eventually lead to the generation of light, optical observations are perfectly suited for this research. He uses optical instruments to observe these emissions from space and from the ground. One of his projects is an array of 21 all-sky cameras that were installed in Greenland, Canada, and Alaska to observe the aurora on a semi-global scale with images taken every three seconds. Such optical imaging inherently generates a large amount of data, and the new quality and quantity of that dataset requires processing techniques beyond simple statistics in order to automatically identify anomalies or events, detect clusters or trends, extract hidden information, and perform classification, especially in combination with other measurements by spacecraft or ground-based instruments.