Choosing a High Accuracy Workflow

Guiding Considerations:

• Project Requirements: The intended use case dictates the necessary level of accuracy. For instance, high-precision topographic surveys delivered to the Engineer of Record may necessitate stricter tolerances than volume calculations used for general progress tracking.
• Site Dimensions: The size of the mapping area can influence workflow selection. Larger sites may benefit from more GCP (Ground Control Point) distribution for enhanced accuracy.
• Drone Capabilities: The chosen drone platform's features impact achievable accuracy. Camera resolution and shutter type are big factors - we want at least a 20MP camera with a mechanical shutter. The Mavic 3 Enterprise is the recommended drone for high-accuracy missions. 
• Correction Options: Availability of RTK or PPK impacts workflow selection. 

High-Accuracy Workflow Options:

The following sections explore five commonly employed high-accuracy workflows:

• GCPs + RTK/PPK + Checkpoints (Ultra-High Accuracy):
  • Ideal for projects requiring exceptional precision (sub-inch accuracy).
  • Utilizes a combination of GCPs, RTK/PPK for real-time or post-processed corrections, and checkpoints for verification.
  • Requires a sufficient number of strategically placed GCPs throughout the site. See our Best practices for GCPs

• GCPs + Checkpoints (High Accuracy, No RTK/PPK):
  • The go-to workflow for scenarios where the drone lacks RTK/PPK capabilities.
  • Achieves sub-inch accuracy when strict best practices are followed, which requires a higher number of GCPs.
  • Involves GCP placement throughout the site along with checkpoints for validation.

• Single GCP + RTK/PPK + Checkpoints (High Accuracy, High Efficiency):
  • Ideal for mid-sized sites or situations where extensive GCP placement is impractical due to logistical or time constraints.
  • Delivers sub-inch accuracy in X and Y coordinates and relies on the single GCP for corrections in the Z-axis.
  • Requires a single strategically positioned GCP along with RTK/PPK and checkpoints for validation.

• RTK/PPK + Checkpoints (Accuracy with Limitations):
  • The workflow for when GCP placement is exceptionally challenging.
  • While offering operational convenience, this method struggles with achieving high vertical (Z) accuracy and necessitates map calibration.
  • Checkpoints in this workflow will provide good measurements of the accuracy of your map in the X and Y-axis. A manual calibration to a known point must be used on RTK/PPK maps that have checkpoints to calibrate out the error in the Z-axis experienced with RTK/PPK only maps. 

• RTK/PPK Only (Unvalidated Accuracy):
  • This workflow should be used when you don't need to validate your accuracy and when you are fine assuming the expected accuracy for these workflows. 
  • While this is the most operationally efficient workflow, it does not offer the ability to validate the accuracy of the maps (no checkpoints).
  • DroneDeploy uses an automatic map calibration method to reduce the error along the Z-axis for this workflow, which eliminates the need for a manual elevation calibration.