AirWorks yields best results with data collected with unmanned aerial vehicles (UAVs) but can process any aerial dataset that has been processed with standard photogrammetry software.
Types of Drones
These types of aircraft have multiple rotor blades that move in a circular pattern around a fixed mast, which is known as the rotor. Common rotorcraft types in aerial mapping are helicopters, tricopters, and quadcopters. Because these do not require a constant vertical thrust, they are much easier to deploy and land due to their ability to lift directly upward. For this reason, they are also easier to maneuver and handle, making flights in dense areas less complicated. One of the downsides of these types of drones is their shorter battery life, resulting in shorter flight times.
Given the benefits and disadvantages of these drone types, we recommend rotorcraft for smaller scale mapping projects.
These types of aircraft have rigid wings such as those of traditional airplanes, thus requiring forward thrust and a runway or launcher to take off for flight. Even though they have a simpler structure and can carry significantly greater payloads in terms of cameras and sensors, fixed-wing aircraft are better suited for more specific aerial mapping projects than the more versatile rotorcraft types.
We recommend using fixed-wing drones for large-scale mapping projects, corridor work, highways, oil & gas pipelines, utility projects, etc.
The sensor that you choose to fly with your drone will vary depending on the site profile, accuracy standards, and deliverable needs of your project. That being said, there are a few types of sensors that might be best suited for your aerial mapping needs.
We recommend a LiDAR sensor that has a higher density of points for collection, which can be reduced in post-processing. Sensors we usually work with range from 200k to 1.5 mil points per second and 100 to 400 scan lines per second; for high accuracy applications, we recommend the highest collection rate in both categories, and for site monitoring or low accuracy applications, we recommend staying in the middle range and balancing points per second with scan lines per second.
The field of view usually has a range of 75-330 degrees, which is okay for most applications but requires tighter flight lines to maintain the 1/2 swath width side overlap. The target echos, or a number of returns from a single pulse, allow for more detail under vegetation and a more accurate bare earth, and less noise. The typical range is 1-15 target echos and we recommend a minimum of 5 target echos for most applications.
Beam divergence is important for identifying the usable swath and flight altitude, the typical range for beam divergence is 0.35 mrad – 3.2 mrad (35-320 mm divergence at 100 m distance to the ground). We recommend the lowest beam divergence to maintain low noise and allow for a higher flight altitude and more space between side overlap but if you have a sensor at the upper range of the divergence, you can compensate by flying at a lower altitude and with greater side overlap.
Inertial Measurement Units (IMUs) put together information from various sensors to provide accurate measurements for orientation, velocity, and pressure altimeter of the drone. Some common IMUs are accelerometers, magnetometers, and gyroscopes. It is possible that these are already built into your aerial mapping UAV. Our application supports data collected with either of these types of sensors, as such, we do not have an official recommendation as sensor choice will depend on your specific project.
Even though you are probably using GCPs to ensure the accuracy of your data, enabling GPS will further validate the accuracy of the aerial dataset. Depending on the accuracy standards your project requires you to meet, you can choose to use either RTK or PPK.
The number of GCPs you choose will also depend on the GPS system you select. Below are our recommendations for the number of GCPs per site depending on whether you select RTK or PPK.
- Minimum of 10 ground control points if using RTK
- Minimum of 10 ground control point if using PPK
- 3 usable ground control points are the bare minimum needed. You should always collect more in the event your RTK/PPK fails.
- Minimum of 10 ground control points per 100 acres, regardless if using RTK or PPK