> For the complete documentation index, see [llms.txt](https://docs.phoenixlidar.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.phoenixlidar.com/spatialexplorer-8-and-9/user-interface/windows/project/ground-control-points-gcps.md).

# Ground Control

Ground control points (GCPs) can be used for accuracy assessment, accuracy reporting, and data adjustment.  To import GCPs into a project, use File->Open to open a CSV file - SpatialExplorer will automatically assume that a CSV contains GCP information. You will then need to specify the coordinate system of the GCPs as well as the column assignments:

<figure><img src="/files/ucCuYmaOYbJzkNizIlpG" alt=""><figcaption></figcaption></figure>

## GCP Type

GCPs are assigned via their **Type** attribute as either **Check, Control, or Unused** points:

* Check and Control points are generally collected at the same time, using the same methodology.&#x20;
* Control points are used for data adjustments, whereas Check points are used for accuracy reporting. Control points appear orange in the main view, while check points appear blue.&#x20;
* GCPs utilized for data adjustments should not be used to validate the accuracy of the data product.&#x20;

Ensure the Coordinate Reference System (CRS) is properly configured to match the CRS that the GCPs reference. For configuring the CRS menu, refer to [**Coordinate Reference System window**](/spatialexplorer-8-and-9/user-interface/windows/project-setup.md).&#x20;

Visually verify the GCPs are properly georeferenced:

<figure><img src="/files/dIbSXbEKLkEXV0VdeTOb" alt=""><figcaption></figcaption></figure>

You can find more information on the principles of ground control usage and collection here:

{% file src="/files/WevkTJDlLBekNMoRUcfR" %}