PPK geotagging

Learn how to assign accurate positions to WingtraOne flight images, including PPK correction data.

If you have a WingtraOne with a PPK module, high precision PPK processing will yield centimeter-level accuracy geotags for your flight images. If you do not have a PPK module on your WingtraOne, please read the Non-PPK geotagging article.

For every flight mission, a folder with the project's name is created on the SD card in the "WingtraPilotProjects" folder. Both the collected images and GNSS data of the corresponding flight are saved in this project folder. You can geotag the collected images in the office after completing multiple flights throughout the day.

You can only apply PPK geotagging on WingtraHub Software. Check out the Install WingtraHub - PPK processing toolchain for information about how to install and set up WingtraHub correctly.

The PPK geotagging process is similar to the non-PPK geotagging process, but with some extra data needed from the user's side. You'll take out the SD card from the camera after the flight(s), put it into the computer, and start the geotagging procedure as follows:

  1. Open WingtraHub software on your computer and select "Processing."

WiH_MainMenu

2. In the "Processing" tab in WingtraHub, select the "WingtraPilotProjects" folder on your SD card or the copied folder from your hard drive.

WiH_Processing_SelectProjectsFolder

3. Projects with PPK enabled are labeled with "PPK" on the bottom right corner of the project boxes.

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4. Select the project(s) that you would like to geotag, then click "Next." You can then define order, sort or search for specific projects.

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5. Define processing details for all projects using the batch options on top of the screen, or you can adjust the settings for every flight individually. When using the batch options, you can still change the settings for specific projects after pressing "Apply to all Projects."

  • Make sure the "PPK processing" checkbox is selected to enable PPK geotagging. Check that the grey PPK dongle is inserted and that the "PPK ready" sign shows up in the bottom left.
  • To save processing time and storage space, select ".csv output only". With the .csv-only option enabled, images will not be duplicated into the OUTPUT folder and will not have embedded geolocation information. Only a *.csv file containing all image coordinates is created. We recommend using .csv to import the geotags into your photogrammetry software, because the geotagging accuracy of each image is only saved in .csv.
  • Select the "Base file(s)" as reference(s) for PPK processing. Please check out the PPK base station article to learn about the different base station options.

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  • Make sure to select all available RINEX files.

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  • Define the base location. Click on "Base location" and then on "Add new" if you have not defined the base location for this project already.

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  • Add a new base station location with high-precision coordinates and give it a descriptive name (it's best to include the coordinate system used). WingtraHub will remember your base locations. Wingtra recommends using WGS84 with ellipsoidal height as the coordinate system for your base location. For more information on the coordinate system requirements, please see the Coordinate systems for WingtraOne PPK article. Once the coordinates are entered, press "Save" and select the newly created base location in the base location selector.
If you use your own base station, enter the coordinates of the antenna reference point (ARP) of the GNSS receiver. If you get a warning that the antenna type can not be detected from the RINEX file, add the offset from the reference point to phase center (APC - ARP) to the field "Antenna offset up."
In case the coordinates of a known point on the ground are given, add the height of the tripod (ground to ARP) to the field "Antenna offset up."

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6. Click "Start processing" in the bottom right corner and observe the processing steps. For batch processing of several projects, WingtraHub will automatically process one project after another.

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7. Have a look at your results. WingtraHub will display the PPK fix percentage and the horizontal and vertical accuracies in meters for each project individually. To access the full output, navigate to /WingtraPilotProjects/SampleProject Flight 01/OUTPUT and inspect the geotag PDF report, the geotags.csv file and the geotagged images. Use the images and .csv for processing in Pix4D, Agisoft Photoscan or the like.

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We recommend you to go through the PPK tutorial to learn more about the details of the PPK geotagging process.

Results of Geotagging

After geotagging, you get accurate geolocation information for each flight image. It is provided in a .csv file in the OUTPUT folder of your project, and if selected in the EXIF metadata of your images.

Here is an overview of the final content of the project folder inside the "WingtraPilotProjects" folder:

  • /DATA subfolder: all GNSS data available for this particular project
  • /IMAGES subfolder: all unmodified images for this particular project
  • /OUTPUT subfolder: all output data from the geotagging process
  • /DATA/date_time.json file: a text file containing time, GNSS coordinates and attitudes for all images (for non-PPK geotagging)
  • /DATA/date_time.sbf file: a binary file containing the GNSS information of the mission for PPK geotagging purposes
  • /OUTPUT/imagename.jpg files: tagged images with GNSS coordinates and exact GPS time embedded as EXIF tags
  • /OUTPUT/projectname.csv file: a geotags text file that contains the relevant meta information for all flight images:
    • image name, latitude [decimal degrees], longitude [decimal degrees], altitude [meter], omega [°] (0° for WingtraOne PPK), phi [°] (0° for WingtraOne PPK), kappa [°] (0° for WingtraOne PPK), accuracy horz [meter], accuracy vert [meter]
    • label, latitude [decimal degrees], longitude [decimal degrees], altitude [meter], yaw [°] (0° for WingtraOne PPK), pitch [°] (0° for WingtraOne PPK), roll [°] (0° for WingtraOne PPK)
    • If Pix4D type .csv file output is selected:
    • If Agisoft type .csv file output is selected:
  • /OUTPUT/geotagging.pdf file: a report that contains all the information regarding the geotagging process
The output GNSS coordinates from the geotagging process for WingtraOne with PPK and WingtraOne without PPK differ! Please refer to the table below for the correct coordinate system

The coordinate system for the output GNSS coordinates from the geotagging process is as shown in the table below:

 

CS_Geotagging

 

To learn more about how to use output data from the geotagging process, please refer to the Image post-processing software article.