Principles of Flight Planning
Here we will discuss how to plan missions for collecting data with your sensor package. It should be noted that you as the operator may choose to make your own flight planning decisions based on your specific operating environment and data collection needs. These flight planning notes should be remembered when making your own decisions to ensure smooth processing.
Terminology
Flight Time: Total time UAV is capable of flight, manufacturer calculations typically performed at MSL in a hover
Mission Time: Total time UAV is capable of carrying out an autonomous flight plan. This number is less than flight time due to accounting for takeoff/landing time, GNSS alignment procedure time, and time to travel to the start point of an autonomous mission.
Area of Interest: The area intended for data collection, minimum area required for capture/analysis
Survey Boundary: Area extended beyond AoI to ensure full data product coverage from post-processing
Total Area Coverage (Flight Lines): Total area covered by UAV, differs from survey boundary when flight lines extend beyond survey bounds.
(Hyperspectral/GPS) Polygon: GPS coordinates used in a polygon file (KML/txt) to trigger Headwall hyperspectral data collection
Hyperspectral Flight Lines: GPS flight line coordinates used in KML file to trigger Specim hyperspectral data collection
Flight Plan Requirements
Flights should be created with the in Flight Planning Calculator mind, referring to the overlap percentage, sidelap percentage, and GSD required from the flight. This will help ensure that collected data meets desired resolution and processing specifications.
When building flight plans, the three most important factors are:
Ensure the aircraft is physically and legally capable of what it is being asked to do
Ensure the flight plan will not put the aircraft in hazards way
Cover the full area of interest with the highest possible data collection quality necessary to guarantee data product viability
Capability
The aircraft must be operated within visual line of sight at all times. Flight planned speed must not exceed aircraft capabilities. Altitude must not exceed legal limitations.
Avoiding Hazards
Ensure the flight plan altitude is set above any obstacles that may exist in the UAV's path. If operating in uneven terrain, proceed with extreme caution. Be aware of the height of all obstacles in and near the survey path, accounting for differences in terrain elevation. Add additional buffer to obstacle clearance altitude in case measurements are off. If possible, flying over the survey at very high altitudes with LiDAR and processing the data will give the most accurate estimation of obstacle heights at all points near the survey.
Area Coverage and Data Collection
The area of interest is the absolute minimum required area that must be covered by the collected data to identify a flight as successful. In order to guarantee the area of interest is fully covered, and the entirety of collected data is of the highest quality, survey boundaries should extend beyond the area of interest. A great rule of thumb is that the survey boundary should be wider than the area of interest by at least 1m for every 1m/s of flight speed.
Therefore, if flight speed is 5m/s, the survey boundary should be at least 5m wider than the area of interest. Hyperspectral sensors require additional extension beyond the area of interest to ensure high data quality. If your payload is equipped with a hyperspectral sensor, please see the Hyperspectral Flight Planning Requirements section for more information.
If your GCS does not allow extending flight lines beyond survey boundaries, the survey boundary can be increased instead.
Ensure all sensors' horizontal field of view extends beyond the edge of the area of interest in the plane perpendicular to the flight lines. Additionally, thought should be given as to where you will enter the field, setup your UAV, and place hyperspectral panels before creating a flight plan. Finally, please ensure that the hyperspectral panels are placed parallel with the flight lines.
Flight Plan Visualization
Pictured below is a study area we want to collect data over. The agricultural field in the center of the image is the area of interest. In this example, the autonomous data collection mission will be performed at 5m/s flight speed. This mission will capture LiDAR, RGB, and VNIR data.
Area of interest is highlighted in red in the figure below.
Overlayed with the Area of Interest is the survey boundary, highlighted in green. Because the flight is at 5m/s, the survey boundary extends beyond the area of interest by 5m parallel to the intended flight lines. For the hyperspectral sensor, a GPS polygon file was created using the same coordinates as the survey boundary corners.
The figure below demonstrates the relationship between the area of interest (red) survey boundary (green), and total area coverage/flight lines (white). Because the flight speed is 5m/s, the flight lines extend beyond the survey boundary by 10m, ensuring the VNIR sensor exits the survey boundary/GPS polygon area for turns, and re-enters once the UAV achieves the proper heading, attitude, and flight speed.
Last updated
