The Sensefly eBee drone coming in to land during a site planning simulation in the Swiss Alps. Photo: Timo Lüge
Most of the time, when you have to build a refugee camp, you have to do so in a hurry. In a typical scenario a lot of people arrive very suddenly and the government decides on where humanitarian organizations can build a camp. Very often the designated land is not ideal – else it would not be empty – and professional site planners have to decide where exactly to build the tents or huts, schools, latrines, showers, medical facilities etc..
3D modelling software is invaluable in this process since it allows site planners to see which parts of the land are too steep to build on, or model where water would collect after heavy rainfalls or if a nearby river floods. That way you can make sure that drinking water flows downhill, that overflow from the latrines does not flow towards the camp or that the health center is in a very safe location.
In order to plan properly, site planners need exact elevation data. As part of the “Drones in Humanitarian Action” initiative, the Swiss Foundation for Demining (FSD) and CartONG took part in a simulation in the Swiss Alps to see if drones can be helpful in this regard.
Orthomosaic of the hypothetical camp site processed in Pix4D
Digital Surface Model of the same area.
Higher resolution
During the simulation site planners emphasised that high-resolution imagery would be very valuable when planning a new refugee camp or when working to improve existing sites. While the participants appreciated the free satellite imagery that is available through the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the consensus was that the image resolution (15 to 90 m/pixel) of the ASTER images falls short of the needs of site planners. Drone imagery on the other hand can provide the required resolutions. For the simulation, CartONG used a fixed wing, eBee Sensefly drone with an optical (RGB) camera to capture imagery at a resolution of 12 cm/pixel. The eBee can achieve resolutions of up to 3 cm/pixel.
CartONG staff looking at data that has just been collected by FSD’s eBee drone.
Photo: Timo Lüge
Control over licensing
One participant pointed out that satellite imagery is subject to licensing restriction, which means that a buyer cannot share the data with all organisations working in a refugee camp. The drone imagery on the other hand would belong to the owner of the drone and could be shared publicly.
Many uses
Additional uses for the drone data that were mentioned by site planners included: Creation of a map with general services and facilities – this would be particularly useful in very big camps. Change detection to see how camps evolve over time. One of the site planners suggested that this might for example show whether different groups within a camp are moving closer together or further away from each other. Obviously, this also requires knowledge of who is living where in the site. Documenting environmental impact: Aerial imagery can be used to document the state of a site prior to it being turned into a refugee site, as well as reforestation efforts where applicable. However, for this purpose satellite imagery is likely sufficient. Monitoring of road and drainage construction: while this can also be done from the ground, one of the participants emphasised that with the help of a drone it could be done much faster. This would then free up staff who could be assigned to other tasks. Drone images could improve the scientific rigour of household surveys by helping enumerators select a representative sample of homes.
One participant also shared an experience where refugees would move shelters within the camp because they did not agree with the layout of the site or preferred to be closer to specific community members. This made it difficult to keep track of who is living where. In these cases, drones could help find the shelters, for example if each shelter had a number written on the roof.
Permissions
On a cautionary note, multiple participants mentioned that it can be very difficult or even impossible to get permissions from the authorities for drone flights in many countries. Since refugees are frequently displaced by armed conflict, rather than natural disasters, the assumption was that authorities in host countries might be very suspicious of the use of drones.
Too many trees
The large number of trees in the area where the simulation took place presented a considerable challenge when creating the Digital Terrain Model. As the drone was not equipped with an expensive LIDAR sensor, the camera could not see through the canopy to the ground. Also, CartONG was using a version of Pix4D which is not able to automatically remove trees with an acceptable quality. This meant that the information manager had to remove all trees manually from the image and fill the gaps with the help of Pix4D with an approximation of elevation profile.
Over the next months, Droneblog will feature summaries of case studies that show how drones are already being used in disaster response operations worldwide. The case studies were produced under the leadership of the Swiss Foundation for Mine Action (FSD) and with funding from EU Humanitarian Aid. The goal of this research initiative is to identify use cases in which cases drones can improve the quality or increase the efficiency of humanitarian aid.
No comments:
Post a Comment