High Altitude Survey Drone Trials Bring Success for South American Company
Ecuador based Pilots Fly QuestUAV DATAhawk at 3700m ASL (12,000ft) for Municipal Tax Calculations
One of QuestUAV's research partners has been running a series of test flights with a 2kg fixed-wing DATAhawk in the Andes, for cadastral mapping and the calculation of municipal taxes. The following case study is the result of trial flights to evaluate the performance of the DATAhawk aircraft at heights above 3000m ASL. Read on to find out about the extreme conditions faced and the challenges of high altitude drone missions.
Prepping for the Flight
There are a wealth of diverse applications for Geographic Information Systems (GIS) and the high resolution, information-rich data they provide. One of the various disciplines supported is the registration of properties through municipal cadaster - storing information that is used for calculation of taxes according to the surface and characteristics of the property. Whilst the data collected can be used directly for these calculations - it can often inform and direct policies that the controlling agencies implement.
Due to the importance of these type of activities, the manner in which the property measurements and characteristics are taken are of the utmost importance. Controlling agencies need to take into account that there are places and regions that are difficult to access to carry out the cadastral survey, as is the case for areas with steep features. Risk to the survey personnel attempting access is also important and it is here where the usage of UAVs is important. UAVs are used to obtain territorial information through photogrammetry, leading to the production of orthophotos that allow the technicians to evaluate the territory remotely with an acceptable precision, with a correspondingly short time until the required information is available.
Land use is rarely arranged in a straightforward manner across flat areas, near populated, low-lying centres - instead being rather distributed throught the region of any particular territorial district. In the case of the town of Quero, which is part of the Tungurahua province in Ecuador, the terrain characteristics are typcial of Andean territories. The common features of these areas are:
- Ground heights of 3000 to 4000m ASL and higher.
- Mostly mountainous or steeply graded landscapes.
- Almost no purely flat areas.
- Areas of interest of mainly populated with agricultural activites embedded alongside.
To evaluate the performance of the DATAhawk aircraft at heights above 3000m ASL, in order to use the aircraft in cadastral updating missions.
Identification of the test site
Any suitable test site must take into account the reality of the landscape in which any future work is to be carried out. In addition, considerations included documentation from QuestUAV, locating a site with good visibility and minimum obstructions found when performing flight operations - especially for landing. In view of the small availability of sites with all of these characterstics in range to be visited physically for evaluation, sites were initially selected with the help of Google Earth. Two test sites were then chosen:
Image 1, Testing site locations (Ecuador, South America)
Image 2, Testing site locations (Ecuadorian Central Andes)
|SITE NAME||12 DE OCTUBRE||SAN ANTONIO|
||-1.462387°, -78.700757°||-1.419822°, -78.610576°|
|TEMPERATURE||5 °C||15 °C|
|WIND SPEED||20 km/h||5 km/h|
|FLIGHT TIME||7 min||11 min|
|COVERAGE||54 Has||24 Has|
In order to carry out the Flight Plan, it was necessary to carry out a site evaluation to determine the location of the ERP and the landing site - all whilst also taking into account the planning and operational recommendations proposed by QuestUAV.
San Antonio Community Case
Aside from taking into account the flight considerations already stipulated by the company, there has also been an emphasis on the physical landscape of the area. In the case of San Antonio, there are no completely flat areas, but rather they present differences in levels over relatively short distance. This makes it necessary to have detailed analysis of the different terrain heights, in order to ensure the aircraft will fly at 400 feet altitude from the initial point and that it won't encounter any obstacles within the safety area. A graphic displaying the heights that would be under the safety radius was made which was used to verify the heights of the land and the obstacles that could put the flight at risk, like trees or houses.
Image 3, Site verification of the polling place and to determine the heights within the security radius.
Image 4, Diagram showing the locations of obstacles under consideration
The flight plan was with the planning software included with the DATAhawk. All previously mentioned requirements were taken into consideration. In addition the safety radius was extended to 800m, due to the terrain conditions and the lack of regulations for UAV flights in our country, which allows for a better range of possibilities when maneuvering the aircraft to fly the course required to collect the overlapping ground images. Care was taken to ensure that a suitable distance was maintained so as not to lose sight of the aircraft.
Image 5, Flight plan created with standard DATAhawk planning software (included)
Each takeoff was performed with the Short Launch Line, due to the height conditions. The launch line allows for greater safety at the time of takeoff, in addition to the providing the initial thrust so that the aircraft could enter in normal flight envelope.
All takeoffs were successful.
Image 6, Verification of the flight plan on-site
Image 7, Pre-flight checks on the DATAhawk
Image 9, Aircraft in flight at 400ft (3135m ASL)
Image 10, Orthomosaic created from data collected during San Antonio trials
Image 11, Orthomosaic created from data collected during San Antonio trials (zoomed)
Image 12, Digital Surface Model created from data collected during San Antonio trials
October 12th Case
The conditions nencountered during the tests carried out in the community on the 12th October were a little different. The selected trial location presented the characteristics of a predominantly flat terrain, however the overall height of the exercise had a base of 3600m ASL. As a result, it was determined to follow the recommended steps during the development of the Flight Plan:
Image 13, Flight Plan created with standard DATAhawk planning software (included)
Image 14, Verifying the flying area and the climate conditions.
Image 15, Pre-flight checks on the DATAhawk
Image 17, Post landing procedures
Image 19, Orthomosaic created from data collected during 12th October trials
Image 20, Orthomosaic created from data collected during 12 de Octubre trials (zoomed)
Image 21, Digital Surface Model created from data collected during 12th October trials
Treatment of images
The results obtained in the two test flights performed are of good quality. This is due to the capability of the aircraft and the design of the flight plans, since the objective was mainly to get an orthophoto of the sector and to verify the performance of the aircraft at high altitude.
The data processed with Pix4Dmapper Pro photogrammetry software is shown below:
Image 22, Data processing performed in Pix4Dmapper Pro
- It is necessary to carry out base and flight checks in addition to the consideration of the terrain at the time of flying. This will help ensure the safety of personnel and the aircraft.
- The aircraft is launched using the added safety feature of a launch line. The use of this feature enables the aircraft to be launched safely in environments with high altitudes.
- The aircraft takeoffs normally and safely for personnel, since the short launch line is a good alternative in places where greater aircraft performance is needed as with high altitude.
- Landing the aircraft safely is the most crucial part of a UAV flight. It is therefore important to have a clear landing site due to the level of care and attention that is required to land the aircraft safely. Should the situation arise where there may not be a sufficient place to land, parachute landing is available as a safe alternative.
- QuestUAV recommend carrying out many test flights until "you lose the fear of control" after which, will make the flights more natural.
- The Q100 DATAhawk drone has fulfilled our levels of expectations of performing in altitudes that are above sea level. The aircraft and sensor captures clear and sharp imagery proving outstanding processed othomosaics and flythroughs. Therefore it is our recommendation that the Q100 DATAhawk drone be used to perform flights in harsh terrains.