A Three-Step Guide to Drone/UAV Flight & Data Collection

Step One: Pre-Flight Checklist

Whether you’re a novice or an expert drone pilot, preparation is key for successful data collection using a drone or UAV. There are a range of variables to consider, including site choice, flight plans, and accuracy of data that can later be processed in Global Mapper Pro®­­­.

Flight Permissions

When studying for both The Recreational UAS Safety Test (TRUST) and Part 107 Certification exams, pilots will learn a lot about flight safety and airspace regulations. The FAA has laid out where you can fly on their website. Please note that restrictions can change depending on conditions, surrounding aircraft, and current events.

In permitted areas, you don’t need approval to fly. However, to prevent any misunderstandings it is never a bad idea to inform neighboring property owners. Urban areas can be more complicated, as the potential for no-fly areas increases. It is the responsibility of the pilot to be aware of changing flight restrictions, adhere to all regulations, and fill out the necessary paperwork for locations that require it. Flying in a closed airspace can have major consequences.

Learn more about FAA Drone Certifications and What It Takes to Fly A Drone.

Environmental Conditions

Flexibility is an important characteristic of drone/UAV pilots. Drone flights for data collection require pilots to consider numerous environmental variables, which can change quickly.

Drone flights must occur in rain-free conditions with low wind. Furthermore, it is ideal to fly when it’s overcast. This reduces shadows and reflections, especially over water and sand, that can impact your data.

The surrounding fauna is also important to consider. Predatory birds can attack and damage your drone, so take note of nests nearby and avoid them. Loose domestic animals on the ground such as dogs or livestock can be an issue for the ground crew, especially during take-off and landing.

Ground Control Points

Ground Control Points (GCP) are measured reference points, tying the collected data to the relevant coordinate system. The placement of your ground control points will depend on your flight plan. Flights typically require a minimum of 3 (recommend 5) GCPs that are well distributed throughout the flight plane. They need to be placed in a highly visible area, away from treelines or other obstructions. They need to be fully detectable from the drone’s aerial point of view, and must be placed before the drone flight begins.

Step Two: Drone Flight Planning & Logistics

Battery Life

Drone batteries are commonly made from lithium, and will degrade if stored at full charge. When not being used, it is recommended that batteries are maintained at storage voltage: approximately 60-70% of the battery’s capacity, or around 3.8 Volts (“Lithium Ion Battery…”, 2017). As a result, it is crucial to recharge your batteries before your drone flight.

The Scope of the Drone Flight

When planning a UAV flight, the drone height will impact the resolution and possible area of coverage. For 3D models, it is recommended to fly at about 150-200 feet, which allows the drone to capture the detailed structure. For more expansive 2D orthomosaics, the drone can be flown at 400ft: the maximum legal flight height within the United States. To fly higher in the United States, approval from the FAA is required.

Drone Flight Time

Standard drone flight times can range from 15 to 45 minutes, and it’s important to consider the (above) variables, including height, wind, and battery life. The flight duration will depend on the quality you are seeking from your end product. For a 3D model, when you fly lower with a higher percentage overlap, the number of passes and time to cover a set area increases. Always consider your battery life in comparison to the estimated time, and pack backup batteries.

Step Three: Technology for the Drone Flight

While bringing a drone to a drone flight might be obvious, there are other tools and technology that are necessary to align the data with the Earth. These include but are not limited to the physical ground control points, GNSS receivers, and a phone with Global Mapper Mobile® for intuitive data collection and seamless transition to post-processing.

GNSS vs GPS Receiver

The position of Ground Control Points are measured with an electronic receiver using satellite time signals, often referred to as GNSS or GPS devices.

Global Positioning System (GPS) is the United States’ collection of satellites. A GPS receiver collects signals only from these (31) satellites. Global Navigation Satellite System (GNSS) encompasses all global satellite systems including GPS and Galileo. A GNSS receiver can collect signals from all of the satellites within the network, offering additional flexibility. For example, if the GPS signal is down, there are still others available to record a location.

Which receiver should you use, GNSS or GPS? Well, it depends on the use case. Even though GNSS receivers are connected to a larger network, each receiver type and brand has different accuracy ratings. You will need to compare the reliability, accuracy, and cost of receivers to see which will work best for your needs. Here at Blue Marble Geographics, we would recommend using both Emlid and Bad Elf receivers.

Data Collection: Global Mapper Mobile

If you are looking for an efficient way to collect Ground Control points, Global Mapper Mobile might be your new best friend. This mobile GIS application allows you to collect the global position of a ground control point, along with any desired attributes, with a few clicks. The free version of Global Mapper Mobile uses the GPS of your device to pin the GCP. Global Mapper Pro offers the flexibility to connect to your GNSS or GPS receiver through Bluetooth. This information can be easily exported to the desktop Global Mapper Pro for post-processing.

To learn how to process your data post-flight, here are great resources:

• Watch our series What It Takes To Fly A Drone on YouTube!
• How To Load Drone Collected Data in Global Mapper
• How To Process Drone-Collected Data with Pixels to Points
• Automatic Identification of GCP in Drone Imagery
• Analyzing Drone Collected Data

References

• “GNSS / GPS Technology Differences.” TerrisGPS, www.terrisgps.com/gnss-gps-differences-explained/.
• “Lithium Ion Battery Safety Guidance .” Massachusetts Institute of Technology Environment, Health & Safety Office, Mar. 2017, pp. 5–6, ehs.mit.edu/wp-content/uploads/2019/09/Lithium_Battery_Safety_Guidance.pdf. Accessed 6 Nov. 2024.
• “The Difference between GNSS and GPS Explained.” Global GPS Systems, 3 Nov. 2020, globalgpssystems.com/gnss/the-difference-between-gnss-and-gps-explained/.