This is the most powerful feature of TerraScan. It uses an algorithm to determine which points represent the bare earth beneath the vegetation.
This review evaluates , focusing on their effectiveness for learning LiDAR data processing within the MicroStation and Spatix environments. The Verdict: A Comprehensive, Steep Learning Curve
In TerraScan: Macros > Run... Select your .txt file. Go to lunch. Come back to a finished project.