Pools of privilege
Detecting swimming areas in aerial images
With cities getting hotter and hotter, cooling has become rather a necessity than a luxury. But who can cool down in summer and who has to sweat? And how is that related to income, neighbourhood or property ownership?
To answer these questions we developed a methodology of AI object detection in images for swimming in cities, in cooperation with satellite journalists and scientists. The new methodology, combining machine learning, aerial photography and geo-analysis, enables to calculate where and how many private swimming pools people put up in a city.
The project idea evolved as a student project student project in a seminar called MAPPING CITIES – MAKING CITIES at the University of Applied Sciences Potsdam, which we were a partner of. Together with the satellite journalists at Vertical52, Marple, Norddeutscher Rundfunk and the scientist Amir Hamedpour, we refined the methodology.
The first results for Berlin were published in cooperation with our German partner Tagesspiegel. Around 23 thousands pools were detected. The amount water one needs to fill them all up could supply the whole city with water for more than half a day. The analysis reveals that rather than a wealth, the space plays a role: pools are especially located in areas dominated by single-family houses.
How to detect private swimming pools with help of machine learning? We used the aerial images and object recognition model from Google and readjusted it after the first attempts and thus “trained” the model for our use case. In order to filter out as many misidentifications as possible, we subsequently checked a quarter of the data manually, and also filtered out implausibly large pool areas of over 100 square meters.
In times of the climate crisis, it becomes vital to cool down in the midths of heat waves. A jump into the cool water is a welcome remidient. Yet, especially in the dense central neighbourhoods of cities there are only limited public bathing options. Our experimental analysis provides an unique opportunity to map which people have an access to such privilege.
