Changelog

This changelog records the changes in the 3D rockfall trajectory model Rockyfor3D since the beginning of development.

Changes in version 6.2.0 (October 2026)

• Integration of new licensing.
• The entire source code was migrated to C++.
• Updated random number generation: the generation of random numbers has been replaced by a thread-safe implementation based on a Mersenne Twister 19937 generator (std::mt19937). The previous implementation based on the random number generator from the standard library (std::rand) was not thread safe and could suffer from duplicate seed values in multiple threads.
• Optimized multi-threading: Multi-threading has been migrated to an implementation based on the C++ standard library.
• The user can choose between ASCII or GeoTIFF raster files as input. The outputs will be saved in the same format as the input data.
• The visualisation of the reach probability in the GUI has been improved. The hillshade in the background now uses the standard algorithm used in ESRI ArcGIS. The reach probability raster is now displayed using a Green-Yellow-Red color ramp.
• The formatting of the net output file has been improved by aligning the columns and headers.
• E_rot and E_trans are listed separately in the calculation screens.
• The number of feeding cells and the reach probability per calculation screen have been added to the net output file.
• The calculation of the energy line angle has been changed to take the total path length of the trajectory into account. The path length is calculated by summing the distance in the 2D plane between the point where a trajectory enters a cell and the point where it leaves the cell (or comes to a stand-still).
• Bug fix: when using the GUI version of Rockyfor3D the total number of blocks listed in the logfile kept increasing with each executed simulation because the corresponding counter variable was not reset. This has been corrected.

Changes in version 6.1.0 (April 2026)

• After an extensive optimisation and verification process using Leave-One-Out Cross-Validation (LOOCV), we concluded that the most robust and realistic version of Rockyfor3D is one without the Ff and Sf function introduced in December 2024. The core of Rockyfor3D will now remain unchanged for the years to come. This optimisation process was based on 377 mapped fresh deposited rockfall blocks (with volumes ranging from 0.05 to 450 m3) from rockfall and rock mass fall events at 38 different sites in Austria, Canada, France, Greece, Italy, Slovenia, Spain, Sweden, Switzerland and the United States. We sincerely thank all users that have been willing to share their data.

Changes in version 6.0.2 (December 2025)

• Adapted the scaling function Sf = 1 / ((Vn1/15.24)^2 + 1); this results in less conservative tangential energy loss during the rebounds and therefore much less optimistic trajectories than in v6.0.1

Changes in version 6.0 / 6.0.1 (December 2024)

• Corrected occurrence of NaN values in the calculation screen (net output) .txt files (v6.0.1)
• Adapted the Logfile to the v6.0
• Correction of cell corner problems that led to excessive velocities/energies
• Reintroduction of the friction and scaling function in the energy loss (rebound) calculation during ground impacts
• Introduction of the total kinetic energy correction based on the total apparent kinematic coefficient of restitution proposed by Noël et al. (2023)
• Introduction of the maximum rotation velocity based on Caviezel et al. (2021)
• Added the option "cliff area weighted" number of simulated trajectories from each start cell to account for the difference in productivity of start cells with different slope angles
• Added the option rapid automatic simulation with low and medium roughness
• Added new options in the command line version
• Corrected errors in the tree impact detection
• Adapted the function that controls energy loss due to the impact height on the tree stem
• Corrected errors in the net impact detection

Changes in version 5.2 (March 2016)

• Adapted the class values of the energy and passing height output rasters
• Added the propagation probability output raster (called Propag_probability.asc) for providing the area specific spatial occurrence probability for risk calculations

Changes in version 5.2 (2014)

• Revision of the Graphical User Interface – adding user-friendly simulation options

Changes in version 5.1 (2014)

• Added E_50.asc, E_90.asc, E_95.asc, E_98.asc, E_99.asc and Ph_50.asc, Ph_90.asc, Ph_95.asc, Ph_98.asc, Ph_99.asc as output rasters to provide different percentiles of total kinetic energy and passing height per cell

Changes in version 5.0 (2011)

• Translation of the Matlab code into C/C++
• Adapted the Rn value for asphalt roads
• Adapted the rolling/small rebounds condition for blocks moving upslope
• treefile.txt needs to be provided without a header

Version 4 (2007 - 2011)

• First stand-alone version of Rockyfor3D based on Matlab (using the MCRInstaller)
• Formalisation of the calculation of the reach probability in Rockyfor3D v4 by L. Dorren (in 2010)

Version 3 (2004 - 2007)

• First Matlab-based version using 3D vectors called RockyFor published by Dorren et al. (2006)

Version 2 (2001 - 2003)

• First simplified, Matlab-based version of Rockyfor (see Dorren et al., 2004)

Version 1 (1998 - 2001)

• ROCKY3: Matlab-based predecessor versions of Rockyfor (see Dorren et al., 2003)
• Slope profile based Matlab simulations and spatially explicit variants leading to ROCKY3