# Ground Control with LiDARSnap

Ground control points (GCPs) can be used with LiDARSnap. LiDARSnap is able to apply variable adjustments to the trajectory to better match control points, which may be required in some cases. There are two ways GCPs can used with LiDARSnap:

## [Vertical Only (Automatic)](/spatialexplorer-8-and-9/user-interface/toolbars/workflow/lidarsnap-v4/ground-control-with-lidarsnap/vertical-only-adjustment.md)

In the **General** tab of LiDARSnap, GCP lists can be enabled. If GCPs are enabled here, **Control Points** will be used only as vertical observations, meaning that LiDARSnap will attempt to align the pointcloud vertically with the position of a GCP. Note that **Check Points** will be ignored. 

This method works well with mobile data sets, where the initial processed trajectory is relatively accurate, and horizontal adjustment to meet control is not necessary. 

## [Full Adjustment (Manual)](/spatialexplorer-8-and-9/user-interface/toolbars/workflow/lidarsnap-v4/ground-control-with-lidarsnap/full-adjustment.md)

Corrections can be created in the [Corrections window](/spatialexplorer-8-and-9/user-interface/windows/corrections.md). **Full Corrections** are used by LiDARSnap as 3D observations. LiDARSnap will attempt to align the selected point with the GCP, to reduce the correction residual. Pre and post-optimization GCP-to-point residuals are displayed in the LiDARSnap report. 

This method is required for many mobile data sets, where control must be used to accurately georeference the scan. 


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