top of page

Join our mailing list


Trajec3D is a three-dimensional rigid body rock fall analysis program that can simulate the trajectory of volumetric bodies during free fall, bouncing, sliding and rolling. Trajec3D is available as "Shareware", where a cost could be required for continuous use in future.

Trajec3D can be installed on Windows XP or above, requires the dotNET Framework 4.5.2 or above, and  the installation available in two formats:

  • Download Trajec3D as an installation package from the top link below - all supporting files that could be required will automatically be installed.

  • Download Trajec3D as a folder with files from the bottom link - unzip and copy the directory to a selected location and manually create shortcuts. The support files are not included, and have to be downloaded separately if required:

Updated to Version on 1 January 2024

Relevant Papers


  1. Rigid body dynamics for rock fall trajectory simulation (Paper presented at ARMA 2012 in Chicago)

  2. Coefficient of restitution for rigid body dynamics modelling from onsite experimental data (Paper presented at Slope Stability 2013 in Brisbane - the first page is the ACG copyright page)

  3. An Evaluation of Open Source Physics Engines for Use in Virtual Reality Assembly Simulations (A 2012 paper by Hummel et al. comparing the accuracy of Physics Engines - Trajec3D uses the Newton Game Dynamics engine that performed well in all accuracy tests)



Trajec3D Information


Trajec3D is a three-dimensional rigid body rock fall analysis program that can simulate the trajectory of volumetric bodies during free fall, bouncing, sliding and rolling. The body shape is selected from a toolbar and the size is a function of the selected geometry, mass and rock density. The physics interaction between materials is a function of the combined properties of the fall body and the impact surface, and three parameters are required:


  • Coefficient of restitution (elasticity);

  • Static friction angle;

  • Dynamic friction angle.


Trajec3D is a modelling tool that enables the quick assessment of many scenarios to better understand potential trajectories that dislodged rocks could follow, the time it should take to reach areas of interest, and an estimate of the energy along the path. Trajec3D is a simplification of reality with the aim to investigate different possibilities, and not a precise engineering design package.


This Beta-version of Trajec3D can be tested free of charge and feedback will be appreciated. Do not be discouraged if I am a bit slow to reply, as I am a full-time employee and travel frequently. My time is thus limited and responses will be managed between other responsibilities.



Getting Started Instructions

Trajec3D is simple to use when the following is known:

  • Import a pit shell as a DXF triangulation file (NOT "Advanced DXF" or "DWG" files).

  • Pit shells can be loaded with "Load - DXF pit triangulation" or by dragging-and-dropping a DXF-file into the scene window.

  • Left mouse button rotates the scene.

  • Middle mouse button pans the scene.

  • Right mouse button or mouse wheel zooms the scene.

  • Double click on any mesh to change the rotation point.

  • Double click on empty space to centre the pit in the middle of the view area.

  • Some buttons act as toggle switches, with a turquoise button background indicating ON. Press the button again to toggle OFF and the background will change back to the default colour.

  • When the "Start"-button is toggled to ON, the right button generates falling bodies as long as the button is pressed and the mouse cursor is on the pit mesh.

  • Hovering the mouse over controls brings up short descriptions of their functionality.

  • The information of a measurement line is written directly above the measurement line - zoom into the start of the line to read the length and dip values.

  • When the graph functionality is activated, hover the mouse cursor over the trajectory of interest to display the graph. The values of the segment of the trajectory directly below the mouse pointer will be displayed above the graph lines.

  • When deleting individual fall bodies or path trajectories, hover the mouse over the object of interest and press the "delete" keyboard button.

Trajec3D Videos

Main capabilities of the current Beta-version of Trajec3D:


  • Load the pit shell as a DXF-file (export the pit shell from a mine design package as a normal DXF triangulation file).

  • Select fall bodies from a range of shapes including spheres, flattened spheres (smartie-shape), rectangular boxes, flattened boxes and cylinders. These bodies are sized according to the mass and density selected, but the shape ratios can currently not be changed.

  • The fall body rotation can be followed with meshes at set intervals.

  • Information is stored along the fall body trajectory and can be graphed as velocity or energy (split into translational, rotational and total energy).

  • Distance and dip measurements.

  • A default pit surface is generated when Trajec3D is loaded - available from Version 1.1.

  • Generation of slopes given the angles and distances, as well as adjustments for crest loss - available from Version 1.1.

  • Ability to change the background colour - available from Version 1.2.2.

  • Construction of catchment fenches - available from Version 1.2.2.

  • Place markers for back-analysis purposes - available from Version 1.2.2.

  • Create a vertical section view - available from Version 1.2.4.

  • Create a grid of particles and "rain" them onto the topography - available from Version 1.2.6.

  • Load custom fall bodies from a DXF-file - available from Version 1.2.6.


bottom of page