3rd July 2019


To construct orthomosaics of several woodland compartments and a wind-blow site along a Cumbrian valley.


Forest Surveys UAV Mapping Orthomosaic DSM DTM Drone Photogrammetry
Forest Surveys UAV Mapping Orthomosaic DSM DTM Drone Photogrammetry


Having acquired some work to assess the progress of compartments of natural regeneration, our team travelled to Cumbria to conduct a number of test flights to acquire imagery of similar natural regen sites. Our client also made us aware of a nearby compartment that had experienced a significant wind-blow event, leaving an already steep, wooded embankment all the more treacherous.

Our team captured the required imagery to create the 3 required high-resolution orthomosaics, which we then used to calculate the percentage of the wooded areas that would be classed as 'open'. The imagery for the wind-blow site, however, proved slightly more difficult to capture.

In order for our UAV to capture imagery of the full wind-blow site, it needed to be launched from the top of the embankment and out over the steep slope. So steep was the slope that our pilot assessed that, despite the UAV maintaining a consistent altitude, the lay of the land would require the UAV to breach the CAA hard limit of flying 120m above ground level. It was therefore decided that the safest option was to collect imagery from two take-off points: one at the top of the embankment to capture imagery of its higher half, and then gather the rest from the bottom.

Forest Surveys UAV Mapping Orthomosaic DSM DTM Drone Photogrammetry

As you can see, the mission was completed successfully and produced a model that our team managed to interrogate fully, assessing the precise quantity of timber on the site. However, launching from the bottom of the slope and venturing into the site, while maintaining the optimum altitude of 65m meant flying the UAV relatively close to the trees still standing around the outside of the site. With the UAV in sight at all times, however, and the camera of the UAV being continually monitored, the flight was successfully completed without incident.