Slides for talk called 3D rasters are powerful and you already know how to use them presented at US-IALE 2017 in Baltimore
Many ideas in the presetation were presented in the following paper. Please use it to cite this work if applicable.
Vaclav Petras, Douglas J. Newcomb and Helena Mitasova. Generalized 3D fragmentation index derived from lidar point clouds. In: Open Geospatial Data, Software and Standards 2017 2:9. https://doi.org/10.1186/s40965-017-0021-8