Flight Planning Issues

Overlap Too Low

Signs of flight issue:

• Not enough photos to cover the area of interests

• Photos were skipped on the flight path

• GCPs outside of flight area which impacts accuracy

• GCPs visible from only two flight lines

Possible recommendations:

• Aerotas Resource: Overlap & Flight Pattern

• Fly at 75/75 overlap to ensure good accuracy and reliability

• Fly at least one flight line beyond required data

• Keep the flight area larger than the GCP distribution so each GCP has an adequate level of overlap

• GCP needs to be captured in 9-16 photos

Overlap Too High

Signs of flight issue:

• GCPs visible in 30+ photos

Troubleshoot:

• Remove photos and reprocess

Possible recommendations:

• Aerotas Resource: Overlap & Flight Pattern

• Fly at 75/75 overlap to ensure good accuracy and reliability

• GCP needs to be captured in 9-16 photos

Impact:

Collecting too much data decreases the accuracy of the finished deliverable because of erroneous matches and the introduction of too much noise in the model.

Unnecessary Cross-Hatch

Signs of flight issue:

Possible recommendations:

• Fly a single, 75/75 overlap, lawnmower pattern flight which helps reduce field time and speeds up data processing

• More data does not mean better accuracy; too much data causes artifacting and noise which decreases accuracy

• Aerotas Article: There is such a thing as too much data

Flight Altitude Too Low

Signs of flight issue:

• Gaps throughout the site due to low overlap

Possible recommendations:

• Aerotas Resource: Choosing Flight Altitude

• Fly/Re-fly at a higher altitude

High Relief: Low Overlap at High Elevation

Signs of flight issue:

• Low overlap

• The flight was flown at constant elevation while the site has elevation changes

• Patchy areas

• Photos that do not calibrate despite not being water or shrubbery

Possible recommendations:

• Aerotas Resource: Choosing Flight Altitude

• Use an autopilot with the Terrain Awareness feature, found in Map Pilot or the DJI GS RTK app

  • Why You Should Use Terrain Awareness

• If not enough data to create terrain, re-fly with terrain awareness

• Terracing missions. Terracing or “stepping down” your missions is one way to deal with elevation change. The idea here is to fly an area with 50-100’ of elevation change at a time as separate missions.

• Take off from the highest elevation on the site. This method is useful if you have a grade change of less than 100’ or so and do not have access to Terrain Awareness. Taking off from the highest elevation ensures that you at the very least, do not end up with too LITTLE overlap.

  • Any more than 100’ of elevation change and this method becomes impractical due to overlap issues becoming more severe.

Not flown with RTK enabled

Troubleshoot:

• PPK Processing or process traditionally if there are enough GCPs

  • PPK Processing Workflow

Possible recommendations:

• Aerotas Resource: P4RTK Field Workflow

• Use the DJI D-RTK-2 base station

  • D-RTK 2 Mobile Station Survey Workflow