1. Description

There are multiple drone flight cases and this article will give the parameters and recommendations for these cases.

2. Flight Parameters for Mining and Aggregates

2.1 Parameters

2.2 Recommendations

• For projects with multiple flights, there should be an overlap between the different flights and the conditions ( sun direction, weather, etc.)
• Recommended camera settings: Exposure time: less than 1/1000 sec; ISO sensitivity: less than 400; Fixed focal length; Infinite focus.

3. Flight Parameters for Trial Fields and Production Fields

3.1 Parameters

3.2 Recommendations

• If there are multiple flights in the same Area of Interest (for a campaign), they need to be co-registered:
  • Set measured Ground Control Points (GCPs): at least one at each corner of the field + one in the middle of the field
  • Or the UAV must be equipped with PPK or RTK function: we recommend using a mobile GNSS station. If you use a fixed known GNSS station, the maximum distance to the Area of Interest is 15km.
• Avoid flying during the azimuth sun period or when the sun is low (shadows)
• Avoid flying when the weather is alternating between sunny and cloudy
• No water or snow over the canopy
• Take pictures of the calibration panel BEFORE and AFTER the flight (multi-spectral). Follow sensor manufacturer guidelines
• Add additional UAV trajectories outside the Area of Interest to ensure collecting enough good-quality pixels within the field boundaries
• Avoid flying over disturbing elements that could affect the reflectance such as buildings or cars.
• (1) The Plant Canopy Size must be equal to twice the GSD. Ex: Canopy size is 8 cm, GSD must be 4 cm
• Specific recommendations for rolling shutter sensors:
  • Stop the drone when taking a picture if drone capacities allow it or:
    • ensure flight speed is max 5m/s and the speed is stable during the entire flight
    • Set shutter time to max 1/600 and stable during the entire flight
  • Overlap: 85%

4. Flight Parameters for Plantation and Forestry

4.1 Parameters

4.2 Recommendations

• If there are multiple flights in the same Area of Interest (for a campaign), they need to be co-registered:
  • Set measured Ground Control Points (GCPs): at least one at each corner of the field + one in the middle of the field
  • Or the UAV must be equipped with PPK or RTK function: we recommend using a mobile GNSS station. If you use a fixed known GNSS station, the maximum distance to the Area of Interest is 15km.
• Avoid flying during the azimuth sun period or when the sun is low (shadows)
• Avoid flying when the weather is alternating between sunny and cloudy
• No water or snow over the canopy
• Take pictures of the calibration panel BEFORE and AFTER the flight (multi-spectral). Follow sensor manufacturer guidelines
• Add additional UAV trajectories outside the Area of Interest to ensure collecting enough pixels of good quality within the field boundaries.
• Avoid flying over disturbing elements that could affect the reflectance such as buildings or cars.
• (1) Flight height must be at least 80m above the canopy (with 80% of overlap) at the highest altitude point
• Specific recommendations for rolling shutter sensors:
• Stop the drone when taking pictures if drone capacities allow it or:
  • ensure flight speed is max 5m/s and the speed is stable during the entire flight.
  • Set shutter time to max 1/600 and stable during the entire flight.
• Overlap: 85%

5. Flight Parameters for Corridors

5.1 Parameters

5.2 Recommendations

• (4) Depending on both the Vegetation Corridor width and expected point cloud density requirement. For ex: the side overlap for transmission lines is 30m
• For projects with multiple flights, there should be an overlap between the different flights.

6. Flight Parameters for Power Line Inspection

6.1 Parameters

6.2 Recommendations

• (1) Especially true for IR sensors in order to not lose effectiveness in the IR inspection
• Suggested Drone: DJI Matrice 200 series
• Suggested sensor: Zenmuse XT2

7. Flight Parameters for Solar Panel Inspection

7.1 Parameters

7.2 Recommendations

• A minimum of 80% overlap is required
• IR camera must be radiometric with a minimum resolution of 640 x 480
• The recommended format is Radiometric JPEG
• Suggested Drone: DJI Matrice 200 series
• Suggested sensor: Zenmuse XT2

8. Calibration Target Best Practices

Follow recommendations from the sensor manufacturer

Complementary Alteia recommendations:

Take pictures of the calibration target before and after the flight. Please note that only one set of images (including one image per spectral band) has to be selected and uploaded in Aether.

Take a picture as close as possible of the calibration target to minimize reflectance from the objects outside the calibration target.

If possible, add a black/mat “tarpaulin” behind the calibration target to avoid disturbing objects on the whole picture. The type of material should be selected attentively to avoid light rays. This is in particular recommended when an irradiance sensor is mounted on the drone.

Avoid disturbing elements on the whole picture (including inside and outside the calibration target): shadow, light rays, reflective object /ground

9. LiDAR Data Acquisition Best Practices

• LiDAR multi-echo: 50 points/m² Number of echos: 3 echos minimum
• The software associated with the LiDAR sensor has to provide a LAS file
• Ground Control Points:
  • The Ground Control Points have to be tagged in the LiDAR software
  • When tagging the GCPs in the LiDAR Software, each drone axis has to be tagged separately.
  • Please contact your LiDAR sensor manufacturer for more information on GCP best practices (type and size of GCPs to be used…)