Ground Control Points (GCPs)

GCPs can be uploaded as CSV or TXT files. Indicate the coordinate reference system of the GCPs. GCPs do not have to reference the same CRS as your project. Use the upload interface to specify the row of the first GCP (to exclude any metadata included in the header, if necessary), as well as to specify which columns contain northing/latitude, easting/longitude, and elevation values:

It is also necessary to set the Type of each GCP. GCPs can be set as either check, control, or unused.

• Control: For each control point, a vertical offset to the point cloud will be computed. These offsets will be averaged to determine a single vertical adjustment to be applied to the point cloud. This adjustment applied to the point cloud, as well as individual GCP to cloud residuals, can be seen in the project report of the SpatialFuser pipeline. No vertical adjustment will be applied if all GCPs are designated as either check or unused.

• Check: For each check point, a vertical offset to the point cloud will be computed. This offset will be visible in the project report of the SpatialFuser pipeline, however it will not be used to adjust the point cloud.

• Unused: Unused points will not have a vertical offset computed. Unused points are typically points that are outside of the scope of the point cloud.

After specifying the CRS and column designations, you should see in the map viewer of the upload interface that your GCPs are georeferenced properly. Each GCP will be labelled by it's ID and offset to a global height model, which can be useful for troubleshooting CRS issues (typically GCP elevations should be within 5 meters of a global height model).