lidar - Keeping only ground points (class 2) with lasground in QGIS 2.14?

I want to keep only the LiDAR ground points in a las file, using the lasground tool from LAStools within QGIS. In QGIS Chugiak (2.4) there used to be an option to "keep class 2", but I don't know how to do it in the more recent version 2.14.

I tried to write in additional command line parameter(s) "keep class 2", but it breaks.

If anybody knows how to do it in lasground toolbox (bin) it would be also fine.

Answer

The command line for using lasground keeping only ground points is:

lasground -i input.las -o output.las -keep_class 2

Don't forget to specify the paths to the lasground tool and the input/output files. For example:

c:\lastools\bin\lasground -i c:\lidar\raw_data\input.las -o c:\lidar\ground\output.las -keep_class2

You can also use lasground for multiple input files at once:

lasground -i *.las -keep_class 2

See the README file for more information.