The latest iPhones now has a Lidar Sensor. It uses laser to measure distances to the environment.
Arboreal Forest now uses the Lidar when measuring the diameter of the tree. It is more accurate, works in dark environment and works better on dense spruces.
We will continue to develop new features in Arboreal Forest. Both with and without Lidar support. But you should use a phone with Lidar if you want the best result.
Here is a movie about the feature.