Citizen science can be fun. Archive: https://archive.today/vyO0Z From the post: >>[Lynnadeng]’s team wanted to monitor the Los Angeles River over time and wanted citizen scientists — or anyone, for that matter — to help. They built a dual phone holder to allow random passersby to use their phones to take photos. A QR code lets them easily send the pictures to the team. The 3D printed holder is fixed in place and has a known gap that allows stereo reconstruction from pairs of photos.