Measuring forest carbon with mobile phones

Tree trunk diameter, currently measured during manual forest inventories, is a key input to tree carbon storage calculations. We designan app running on a smartphone equipped with a time-of-flight sensor that allows efficient, low-cost, and accurate measurement of trunk diameter, even in the face of natural leaf and branch occlusion. The algorithm runs in near real-time on the phone, allowing user interaction to improve the quality of the results. We evaluate the app in realistic settings and find that in a corpus of 55 sample tree images, it estimates trunk diameter with mean error of 7.8%.