Drones improve forest management in Kenya
August 2019, the sun shines over the Mau forest, but not for long. Daily rains lower the temperature and make the work harder. Drone Adventures is here to map the Kenyan forest with the help of the local community, the University of Milan, and the Association Mani Tese.
Here are some key mission numbers:
Area mapped: 6000 hectares
Resolution: 4.4 cm/pixel
Flight height:150 m above ground
Number of flights: 21 in 5 days
Flight duration: 1 hour
Images collected: 8700
Marco Cortesi, a geography graduate at the University of Milan, writes his thesis on the management of the Mau forest under Professor Valerio Bini’s supervision, a member of Mani Tese. Drone Adventures is represented by Enrica Soria and Anthony De Bortoli, who offer technical solutions for cartography and manage the flight campaigns. The team has agreed to perform a mapping of the Ndoinet forest (6000 hectares of the 20 000 total surface) at a resolution that allows the localization and counting of animals (mainly sheep and cattle) and distinguish the different types of vegetation.
The mapping is realized with the help of two senseFly eBeeX fixed-wing drones equipped with RGB cameras. Flights are performed with a final resolution of 4.4 cm/pixel. Enrica and Anthony take care of the flight planning and divide the mapping area into smaller sectors to optimize the flight time and the number of launches. With each hour-long flight an area of about 300 hectares can be mapped, in the absence of rain and wind lower than 10 m/s. The total area mapped over a week is approximately 6,000 hectares with 21 total flights over the 5 days.
During the week, the Kenya Forest Service (KFS) and the members of the Community Forest Associations (CFA) help the team to find their way around the place, whereby we learnt a lot about the type of forest and challenges of managing it.
Besides frequent rain and episodes of wind speeds over 10 m/s (40 km/hour), the terrain was challenging to maintain the communication link with the drones. A 40 meters tower located at the edge of zone therefore played a key role as base for the groundstation including the ground modem.
The local community was very interested in this new technology and besides learning everything about mapping drones, one or the other also got the chance to launch and fly them themselves.
Back in Switzerland, the members of Drone Adventures, Andrea Blindenbacher and Alex Habersaat have created an orthomosaic of the entire area using the photogrammetry software Pix4Dmapper. This large image of about 300 megapixels, gives an overview of the area and can be used for vegetation analysis.
Processing and file sizes are a challenge to handle there. The solution was to break up the orthomosaic into smaller ones for easier handling. These would allow the retrieval of GPS positions of locations of interest and allow the rangers to get a better grasp of vegetation.
For animal counting, the single images of the dataset were used—a total of 8700 images at 20 megapixels each.
All in all the entire mission was a success and able to deliver enough data for further analysis and advancement in the field for forest management in Africa.
Author: Enrica Soria
Image credits: Marco Cortesi
This project couldn’t have taken place without the fantastic collaboration of Drone Adventures with:
A giant thanks to our technology partners: