Using Multi-Source Data to Capture the Impacts of Earth Hour 2021: A Case Study of Hong Kong

Earth Hour is an annual campaign to turn off non-essential electric lights for one hour as a symbol of commitment to our planet. Small gesture as it may be, this one-hour event may lead to temporary reduction of energy usage and light pollution. In Earth Hour 2021, we conducted a large survey in Hong Kong to see its impacts using multi-source open and volunteered-crowd-sourcing data. These data were collected from 120 traffic cameras, 27 weather cameras, 2 panoramic 360 cameras, 1 wide-field camera, 7 all-sky cameras, 10 cellphones of volunteers, and 1 camera recording videos onboard of tramway. By analyzing the multi-source images and videos, we identified 122 individual buildings that participated in Earth Hour 2021. We further demonstrate in detail using image analysis techniques the extent of light pollution reduction in an urban environment. Finally, we present a demo experiment to identify light sources using artificial intelligence (AI) techniques.