Quadcopters can significantly decrease the time necessary to complete terrain mapping.
Battery management, logistics, and scouting can overcome most problems.
By Mark Chesterman
Unmanned aerial vehicles, especially commercially available ones, have numerous applications, one of them being surveying or, to be more specific, terrain mapping. Traditional zone mapping is a time-consuming process, and it usually involves a lot of workforces. Quadcopters and fixed-wing drones can significantly decrease the time necessary to complete such an undertaking, but they too are faced with various challenges. This article discusses the major challenges faced by drone operators in the field and some solutions.
Major terrain mapping difficulties
Quadcopters and fixed-wing drones are not infallible terrain mapping tools. They are subjected to factors, both internal and external. For instance, as a surveyor, two challenges to overcome even before hitting the field are related to power and transportation. To simply put it — more area to cover requires more power. There’s also the matter of transporting your drone from one place to another. Such an obstacle can be overcome with a carrying case or securing alternative means of transportation (car, train, plane, etc.).
These are only a couple of examples of challenges to circumvent in terrain mapping. Major issues to address during surveys include taking off/landing, an area’s accessibility, weather conditions (rain, snow, wind), how much of the work zone can be mapped, and, of course, transportation.
Taking off and landing — One of the first adversities to overcome is related to taking off and landing your UAV. Bear in mind that in the case of a quadcopter, you will need a flat surface and an open space for both landings and taking off. Scouting the terrain should be a prerequisite, as an obstructed landing/taking off place (low branches, tall grass or another sort of vegetation) can deplete your UAV’s batteries and leave you with little time to take readings or measurements.
Fixed-wing drones, much like the ones used in the military, need more space to be deployed than quadcopters. If you prefer fixed-wing crafts, be sure to find a long and straight path to launch and land it. Don’t forget that successful take-off means you will have more battery available for your project.
Accessibility — When scouting an area for terrain mapping, determine if ground control points (GCPs) can be deployed. Look for anything that might make GCPs not feasible — swampy terrain, marshes, overgrown vegetation, or areas that are otherwise inaccessible. If the situation dictates, consider using a post-processed kinetic module instead of GCPs or a real-time kinetic model. This drone attachment allows you to add geotags to the photos taken by drones. Using these tags, you will be able to create powerful and highly accurate 2D models of the surveyed area.
Weather conditions — Of course, sunny and warm weather is the ideal choice for terrain mapping, but Mother Nature takes orders from no man. Really bad weather such as winds of more than 40 kilometers per hour, snowstorms, and heavy rain mean you have to pack up your surveying equipment and go. If you’re dealing with only a light breeze, piloting the drone should not be too difficult. It doesn’t matter if you’re employing a quadcopter, fixed-wing, in-built wing, or hybrid drone because they all have an increased wind-resistance factor. If the wind picks up in speed, don’t force the drone’s controls to keep it on the path. Let it glide for a while before assuming control. Any extra commands will take a toll on the battery.
Area to map — The concept is easy enough to grasp: More space to cover means you’ll be using more of that power reserve. At this point, you must figure out which type of drone you’re going to use to cover the whole area. Quadcopters are inefficient at covering large areas, being more suitable for small-area mapping. If your project calls for surveying a large area, it’s better to employ a hybrid, in-built wings, or fixed-wing drone. These models take advantage of the design to glide through the air, using very little power.
Transportation — The last challenge to overcome during terrain mapping is related to transportation. For instance, if you are put in a position to survey an island with a quadcopter, you must choose at least take-off and landing spots to cover the whole surface. In our experience, the best way to ensure that the drone reaches the next destination safely is to buy a carry case or a reinforced backpack. Additionally, it’s easier to transport a drone to various take-off/landing spots with a car or other vehicle.
Terrain mapping with UAVs is an interesting undertaking but not without challenges. Most of them are related to battery management, logistics, and scouting. However, with a little planning, you can easily complete the task.
Mark Chesterman is a drone aficionado and a technology enthusiast who provides comprehensive drone reviews on http://droneista.com.