There are numerous methods for classifying ground and not-ground points from raw LAS point clouds. They all do a great job, depending on local circumstances, but inevitably even when algorithm and terrain are well matched there are some exceptions. How to clean up those outliers? Are there any tools out there in which one can interactively lasso a collection of points and manually change some attributes? E.g. like in a paint program?
Horizontal 3D view of LAS point cloud with all "non-ground" points removed, however some points are mistakenly still classed as "ground".
Viewpoint top down view