Submitting Ground Control/Checkpoints with Your Survey Dataset


When uploading a survey dataset, it is always best practice to add ground control points (GCPs) to increase the accuracy of your data.

You can also select which points you wish to use as checkpoints from your ground control points. These points will not influence the model—but will be used to validate the model's accuracy, which is a common practice in surveying.

There are four options for adding ground control and/or checkpoints to your survey.

  • Adding an AeroPoint flight.
  • Uploading a CSV file with ground control points. 
  • Adding both an AeroPoint flight and a CSV.
  • Not adding ground control. 

Adding an AeroPoint Survey

Propeller’s fully automated processing is the simplest way to collect ground control point locations. Choose an AeroPoint survey from the list of flights in the AeroPoints dashboard.  

Choose the method by which you would like to Process your AeroPoint survey.

Propeller Corrections Network

Global Survey Benchmark or Local Survey Benchmark

Rinex Upload

Unreferenced

Check out this article for more information on different types of AeroPoint surveys.

If the site does not already have a default system set, you can set it by turning on Save this coordinate system as default.


Note: if you submit a dataset to a site with a local system, the coordinate system will be preset to this system.

Upload AeroPoints + CSV

Click the AeroPoints + CSV file and choose the AeroPoint flight from the list of AeroPoint Surveys.

How to format GCP data CSV file

Click Download CSV file template to download a template file for submitting GCP data in the correct format. The template's column structure ensures that columns can be auto-detected.

Process_AeroPoints_Download_CSVTemplate.png

Please note that if you are using a CSV file you must include the following information in the column headers:

For PPK and RTK

  • ID: a unique name for each GCP.
  • Easting / Longitude / x: number specifying x coordinate.
  • Northing / Latitude / y: number specifying y coordinate.
  • Elevation / z: number specifying z coordinate.

For Lidar

  • Name: a unique name for each GCP.
  • X: The number specifying the x coordinate. For column headers, you can also use easting, eastings, east, longitude, long, lng, or e.
  • Y: number specifying y coordinate. For column headers, you can also use northing, northings, north, latitude, lat, or n.
  • Z: number specifying z coordinate. For column headers, you can also use elevation, elev, height, orthometric height, or z.

Optionally, an additional field Purpose can be assigned. If this column contains the value "CHECKPOINT," that point will be registered as a checkpoint. Otherwise, it will be included as a ground control point.

Drag and drop or upload the CSV file.

Confirm control point locations and select checkpoints

If you have chosen AeroPoints or configured a CSV file, a map showing the approximate locations of your ground control points will be displayed. If they are outside the boundary of your photos, a warning will show, and the list icon will be displayed in red, as below. If this is unexpected, ensure that:

  • You have chosen the correct AeroPoint flight.
  • You have selected the right coordinate reference system.
  • Your CSV coordinates are in the selected units for your coordinate reference system / local grid.

Alternatively, these points can be removed by toggling on the Remove these points switch. Then all points outside the survey area will be omitted from the dataset.

In this pane, you can select which points from your CSV file and/or AeroPoint flight (collapsed below) you wish to use as checkpoints by toggling the Checkpoint switch.

Upload CSV file only

Ground control points can also be submitted as a CSV file.

If you’re using a PPK drone, you must remove the .MRK and .BIN files from your data upload to use the .csv method of uploading GCPs.

To remove the MRK and BIN files from your upload, click the trash can icon next to the file in the Uploader.  

Click NEXT and name your dataset.

DataUpload_Dataset_Details2.png

Click on CSV file to upload your GCP information.

Similar to adding a CSV and AeroPoints workflow, there are required fields.

For PPK and RTK

  • ID: a unique name for each GCP.
  • Easting / Longitude / x: number specifying x coordinate.
  • Northing / Latitude / y: number specifying y coordinate.
  • Elevation / z: number specifying z coordinate.

For Lidar

  • Name: a unique name for each GCP.
  • X: The number specifying the x coordinate. For column headers, you can also use easting, eastings, east, longitude, long, lng, or e.
  • Y: number specifying y coordinate. For column headers, you can also use northing, northings, north, latitude, lat, or n.
  • Z: number specifying z coordinate. For column headers, you can also use elevation, elev, height, orthometric height, or z.

Optionally, an additional field Purpose can be assigned. If this column contains the value "CHECKPOINT," that point will be registered as a checkpoint. Otherwise, it will be included as a ground control point.

Note: Geographic coordinates must be expressed in decimal degrees.

Drag and drop a correctly formatted CSV file onto the screen or click Upload GCP file.

Column names are auto-detected but must be checked to confirm which column each required data field is in. If your file has a header row—the first row contains the names of the columns as in the template file—select This file has a header row

If auto-detection is unsuccessful for all columns, select which columns correspond to each required data field. If the GCP data file has more than four columns, scroll across to reveal the additional columns.

Confirm control point locations and select checkpoints

If you have chosen AeroPoints or configured a CSV file, a map showing the approximate locations of your ground control points will be displayed. If they are outside the boundary of your photos, a warning will show and the list icon will be displayed in red, as below. If this is unexpected, ensure that:

  • You have chosen the correct AeroPoint flight.
  • You have selected the right coordinate reference system.
  • Your CSV coordinates are in the selected units for your coordinate reference system / local grid.

Alternatively, these points can be removed by toggling on the Remove these points switch. Then all points outside the survey area will be omitted from the dataset.

By toggling the Checkpoint switch, you can select which points from your CSV file and/or AeroPoint flight (collapsed below) you wish to use as checkpoints.

Process_AeroPoints_CSV_SubmittedControlPoints.png

Comments about your GCPs

You can leave comments about your ground control points which will be picked up during processing. This is best suited to describing positions of points that are hard to locate or any special requests. Click NEXT to complete this step.

Uploading_Comments.png

No GCPs

Submitting a Survey without ground control will reduce the possible accuracy of your outputs click CONTINUE to acknowledge the warning if you want to proceed.

DataUpload_NO_GCPs.png


I still can't do it!

We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.

If you're stuck, the Propeller hardware support team may be able to help. You can contact our support team by emailing hardwaresupport@propelleraero.com.au.

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