When uploading Survey dataset, it is advisable to add ground control points to increase the accuracy of your data.

Optionally, 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 instead will be used to validate the accuracy of the model, which is a common practice in surveying.

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

  1. Adding an AeroPoint flight.
  2. Uploading a CSV file with ground control points. 
  3. Adding both an AeroPoint flight and a CSV.
  4. Not adding ground control. 

AeroPoints:

Choose your AeroPoint flight from the list, which is sorted by flight date. You can use the search bar to search by location name or AeroPoint flight ID. Scrolling to the bottom of the list will load more if they are available.

Click on a flight to choose it. A flight can be unselected by clicking on it again.

If a chosen flight is invalid, it will appear with a red outline and a description of why it cannot be used. In this instance, clicking Process Flight will open up the AeroPoints Dashboard.

You must then select a horizontal and vertical coordinate reference system to produce your outputs in. The systems visible in the dropdowns are those that are compatible with the selected AeroPoint flight. These inputs will be prefilled if there is a default available from the selected site or the AeroPoint flight.

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

Note: if you are submitting a dataset to a site that has a local system, the coordinate system will be preset to this system.

Upload CSV:

Ground control points stored on your computer can be submitted as a CSV file.

If you are not working in a local system (see above) you must first select a horizontal coordinate reference system that your CSV coordinates are in. This inputs will be prefilled if there is a default available from the selected site. This is also the system which we will produce your outputs in.

Note: The vertical datum need not be selected here—output elevations will reflect the "height" value input by 

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

How to format GCP data CSV file

A template file for submitting GCP data in the correct format is is available for download by clicking Download CSV file template. Using the column structure from the template ensures columns can be auto-detected.

The required fields for GCP data are:

  • ID: 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

Optionally, an additional field Purpose can be assigned. If this column contains the value "CHECKPOINT," then 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—i.e. 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 not successful 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 will be displayed showing the approximate locations of your ground control points. 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; and
  • 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.

GCP comments

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 which are hard to locate, or any special requests. Click NEXT to complete this step.

No GCPs

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

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