PPK Processing

DroneDeploy Auto-PPK Solution

Available for Advanced, Teams, and Enterprise subscriptions

Background on PPK

PPK is a GPS correction technology, like RTK, that corrects geotagged image location data. Observations data is collected from the base (VRS) and rover (drone) and corrected after the drone has captured images, thus being "post-processed." Learn more about PPK vs. RTK in a recent blog update.

Value of PPK

Users in remote areas (or areas with signal interference) can create high-accuracy maps without relying on RTK connectivity. Longer flights over varied terrain can have difficulty maintaining a fixed RTK connection; in these cases, we can still salvage a highly accurate map through PPK. Through our implementation, which uses Virtual Reference Stations (VRS), users do not need to supply their own base for observations, which eliminates the need for costly additional hardware.

Earthworks and mining operations at very large sites and/or where RTK network strength and/or cellular connectivity is poor or unavailable are common users of PPK workflows.

Supported Drones

1. DJI M3E RTK
2. DJI Matrice 4 Enterprise/Thermal
3. DJI P4P RTK
4. DJI M300 & M350 RTK
5. Autel Evo II Pro RTK
6. Skydio X10 RTK

Supported PPK base stations and corrections data

Ideally, capital-intensive job sites (e.g., large commercial projects, civil projects, or mines) will run continuous observations so that local base station observations are always available.
We recommend Trimble GNSS receivers, but you can test with any receiver.

Setting up your Base Station

Here are some key requirements to keep in mind:
The base does not need to be set up on a known point,
The base must record for a minimum of 1 hour (completely overlapping the drone's flight)
The base must export an OBS file or .0-23O file

Steps to upload and use DroneDeploy's Auto-PPK Solution

In summary, after the flight, the user uploads the Survey folder via Smart Uploader (containing observations data + images) from any DJI RTK drone for fully automatic high-accuracy PPK processing (US and EU only).

1. Fly your mapping mission as usual, with the RTK module connected to the DJI drone in good repair.
2. From the  desktop, navigate to Upload
3. Select New Upload to open Smart Uploader

4. Select Choose Files

5. Navigate to a compatible drone's "Survey" folder and select its contents (.jpeg images + .obs + .mrk data).
   1. Smart Uploader recognizes an image set as being ready for PPK processing.

You can also choose "Add Base Data" under the the dot menu.
Drag and drop your Base Station's OBS file or .0-23O. Click Process

Note: The range of observation coverage by the base station needs to be over an hour and completely overlap the drone's flight. If additional observation time is uploaded, the Smart Uploader can trim this to the relevant corrections during processing.

6. Could you complete your upload as usual and wait for the completed results?

Understanding the Processing Report

To access the processing report, click here.

This new section of the Processing Report details any trajectories processed using Post Processed Kinematic (PPK) to improve map accuracy. 

The chart shows the image coordinates' standard deviation (estimated accuracy) for each axis. As a general rule, one can expect the Z-axis accuracy to be triple that of the X and Y. This is due to the positions of the satellites relative to the receiver.

Typical PPK convergence summary in Processing Report

PPK Status: This is the overall quality indicator of the map's processing status. If it shows an error, contact support. 

Datum: This is the datum and epoch in which the flight was processed. It can be used to compensate for tectonic plate movement when re-projecting to a different coordinate system.

Successful Trajectories: When a map is processed with multiple trajectories, some or all may fail to process. A trajectory is created for each battery change. If any have failed, contact support.

Median Standard Deviation: This represents the delta between the initial and solved camera positions. As with RTK, it's important to note that these figures represent the deviation of the solved camera position before photogrammetry, NOT the final map's absolute accuracy.

FAQ's and Known Limitations

• What geographic regions are supported today?
  • The service areas are split into two regions:
    • Fast Region (Central Europe and North America)
    • Global Region (Rest of World)
  • The Global Region corrections are based on a global ionospheric model. At the same time, the Fast Region uses a denser network of reference stations to compute a regional ionospheric model for atmospheric corrections.

• Are there limits to the dataset upload? 
  • Yes, your OBS file cannot be larger than 500MB. 
    
    
• How long must I fly for?
  • Fast Region:
    • Convergence time is at least 10 minutes
  • Global Region:
    • Convergence time is at least 20 minutes
      
      
• What if my map time is under 10 minutes? 

  • Convergence occurs as images and their corresponding locations are logged. In our PPK graph, you can see that convergence (when the standard deviation drops) is a function of the number of images taken. Time is how we reflect the image count. You will need to be in the air capturing images for at least 10 minutes for PPK to apply to your dataset. 
    
    

• What should I expect in terms of accuracy?
  • Expected accuracy is < 3 cm horizontal RMS error and < 6 cm vertical RMS error. This is independent of the region as long as the solution has converged.
    
    
• When is my drone collecting observations?
  • While powered on.
    
    
• Does PPK increase my processing time?
  • Yes, but only marginally (<15 min addition in expected processing time).
    
    
• Do I have to fly with DroneDeploy's Flight App?
  • No, we support processing data sets captured in various ground control apps.
    
    
• Do you know if I still need GCPs or Checkpoints? 
  • As with RTK, PPK maps will generally be more accurate than a non-RTK/PPK map without GCPs.DroneDeploy still recommends using GCPs for the highest level of absolute accuracy (as well as checkpoints to verify against known benchmarks).
    
    
• Does DroneDeploy support Skydio X10 RTK/PPK?
  Yes! DroneDeploy will process images captured with the X10 that already have RTK corrections or will automatically apply PPK corrections if you fly with the RTK module attached.