Very cool project:
For any city, thousands of geotagged photos are available online. The project maps these photos in the places where they were taken.
A custom-built camera flash + smartphone setup queries the Flickr and Panoramio APIs for photos taken at the current geographical position. Whenever there’s a photo available, a flash is triggered.
Long-exposure photography captures multiple flash lights — each representing one geotagged photo — and situates them in the place of their origin.
Head over to the project page for more photos, process as well as technical details: philippschmitt.com/projects/lightpainting