原文
I've been working on this project for about 4 years. It began as terrain only because world wide elevation data was publicly available. I then added buildings from OpenStreetMap (crowd sourced) and more recently from Overture Maps data. Some computer vision/machine learning advancements [1] in the past few years have made it possible to estimate tree canopy heights using satellite imagery alone making it possible to finally add trees to the map. The data isn't perfect, but it's within +/- 3 meters of so. Good enough to give a general idea for any location on Earth. Happy to answer any questions.