The drones use Lidar (light detection and ranging), which works like radar but uses light instead of radio waves.
Laser pulses are fired at the trees below and the time it takes for wavelengths to bounce back is used to create a 3D picture of what lies beneath.
It enables you to pick out features that a satellite doesn't allow you to do...Richard Tipper, Executive Chairman, Ecometrica
The programme is led by Edinburgh-based company Ecometrica. Its funding partners are the Forestry Commission Scotland, Scottish Orienteering, Woodland Trust and Edinburgh University.
Support has also come from the UK's Science and Technology Facilities Council. Once it is in the air, the four-rotor drone is easier to hear than see...