Learn CST

The Official Online Training Resource for the National Society of Surveyors (NSPS) Certified Survey Technician (CST) program.

  • About
  • Contact
  • Downloads
  • News
  • Account
You are here: Home / Archives for Drone Mapping

How Critical is Your Drone Flight Pattern? Does it Make a Difference?

Here is the mission. The area shown in RED needs to be mapped with 1′ contours and rectified orthomosaic. How many Ground Control Points (GCPs) are needed and what would be the the best way to fly the mission?

Choosing the right drone flight pattern

Area to be mapped
Area to be mapped

Three different flight patterns were flown to determine which method is better. A, B or C?

Drone flight pattern option A
Drone flight pattern option A
Drone flight pattern option B
Drone flight pattern option B
Drone flight pattern option C
Drone flight pattern option C

Several permanent Ground Control Points (GCPs) and check points were placed along the dam for testing purposes.

Overview of Ground Control Points
Overview of Ground Control Points

Six GCPs were selected for balanced aerial triangulation. Then the camera optimization was ran to calculate the RMSE values.

Aerial triangulation example
Aerial triangulation example

The site was flown with a Mavic 2 Pro. Rolling shutter compensation was turned off for the initial comparison results.

Below is the result for pattern A.

Drone flight pattern result A
Drone flight pattern result A

Below is the result for pattern B.

Drone flight pattern result B
Drone flight pattern result B

Below is the result for pattern C.

Note: GCP 1 & 2 was not included in flight pattern C.

Drone flight pattern result C
Drone flight pattern result C

Reviewing the Check Points RMSE values, flight pattern C yields the best result for the horizontal position.

Flight pattern B yields the best result for the vertical position.

———-

Reviewing the Control Points RMSE values, flight pattern C yields the best result for the horizontal position.

Flight pattern C yields the best result of the vertical position.

———-

For this particular mission, flight pattern C was used for the final results.

All control points were used as GCPs.

Without rolling shutter compensation.


With rolling shutter compensation.

Final 1′ contours

Final 1' Contours

The flight pattern along with the right number of GCPs placed in strategic locations is the best solution for 3D survey mapping.

There is always going to be floating error and one solution may not work with every flight scenario.

The trick is to look at the mission flight area and plan accordingly to determine the best approach to minimize any errors.

Different sensors will result in different solutions. Not all drones/sensors are equal.

Remember the deliverables are the key factor. Select the sensor that will meet the deliverables. Select the drone platform that can carry the sensor.

Each sensor/lens combination will have distortion. Calculate the Neat area for each sensor to be able to determine the right sensor for the deliverables. Different sensors will need a different number of GCPs in strategic locations to meet the deliverables.

The higher the micron value “µ”, the more information that can be stored per pixel. Anything above a 1.5 µ is recommended for 3D mapping.

NOTE: The higher megapixel does not always mean a higher µ value. See the chart below.

Conclusion? When it comes to choosing drone flight pattern, doing it right takes some work and planning.

###

LearnCST contributor Jim Crume created the Survey Mathematics Made Simple and Survey Mapping Made Simple book series to showcase the technical aspects needed to become a professional design level mapper. 

Previous Article: How to Start a Design Level Drone Mapping Business

Written by Jim Crume · Categorized: Features, News · Tagged: Drone Mapping

LearnCST News and Updates

  • Opening Alert: BLM Student Trainee Pathways Internship positions April 12, 2023
  • Now Accepting Q2 Exam Applications April 7, 2023
  • Now Accepting Q1 Exam Applications January 3, 2023
  • About
  • Contact
  • Downloads
  • News
  • Account

© 2014-2023 LEARNCST, SPATIAL MEDIA LLC