This tool will adjust the selected lidar point position to move towards the specified terrain surface (Z movement) or trajectory file (X,Y and Z movement), based on a percentage of adjustment. The selected points will be adjusted in position in the existing layer.
Select lidar points with the 
digitizer tool, then navigate to Move/Reshape Feature > Adjust Selected Lidar Towards Surface...
Surface(s) to Adjust Towards
Specify the loaded terrain surface(s) that the points should move towards. Each point will adjust towards the closest surface.
Adjust Amount
The Amount slider decides how much movement towards the surface area the points are to be repositioned, 100 % equals full movement towards surface or trajectory, placing the point on the surface. A value of 50% means that the points will be moved 50 % of the distance towards the surface/ trajectory.
Move Points Along Pulse Trajectory File (.trj or .txyz)
This option will move the selected lidar points along the line between the Lidar sensor and the point, towards the surface. This calculates the sensor position using the GPS-time and flight-path in a trajectory file. The trajectory file can be a TerraScan trajectory binary file (.trj) or a text file “.txyz”-format. The text file is a tab delimited text file with the following attributes: (GPS-)Time, Easting, Northing and Elevation as point / line vertex attributes.
If this option is selected and multiple surfaces cross the pulse trajectory, movement will be made towards the surface closest to the sensor.
Move Towards Nearest Surface
This will adjust the Z value of the selected points to move the specified adjustment amount towards the closest surface.