Infrastructures / collectors¶

Linear elements
Infrastructures from LiDAR

This section deals with the steps to generate the infrastructures, which act as collectors during the simulations. These must be represented in the point cloud format with points spaced about half a diameter d1 from the smallest block to be simulated. Each first impact of trajectories coming into contact with an infrastructure is recorded there, and the information is relayed via the trajectory to the source. This helps identify potentially problematic sources (e.g. to guide field inspections, or planning scaling and bolting/stabilization work). This also makes it possible to highlight the problematic paths taken by the rocks allowing them to reach the infrastructures, for a better planning of the positioning of the barriers (nets, walls, etc.).

Infrastructure can be built in different ways. Linear elements can be constructed for example from polylines or shapefiles, as described in the "Linear elements" section. It is also possible to develop them from existing point clouds (e.g. ALS points classified as infrastructures), as described in the section “Infrastructures from LiDAR”.

Linear elements ¶

Linear elements can be generated in the same way as the fences, but without requiring the steps necessary to tilt them.

Generating the linear element ¶

This short step takes over the concepts used to generate the fences, but this time applies them to generate the linear element. The linear element can be generated manually by drawing a polyline with the Trace Polyline tool.

Linear elements can also be generated from polylines from shapefiles. These lines can be imported into CloudCompare and then projected vertically at ground level if they do not have elevation information allowing them to be displayed in 3D at ground level. To do this, the Extract Sections tool can be used with the selected terrain elevation data. The Polyline import option allows you to add the polylines to be projected. The Extract sections option can then be used to project the polylines at ground level.

Note: Linear elements represented by shapefiles often actually have a certain width (e.g. a motorway with several lanes). It may be necessary to add a buffer zone corresponding to the desired width, and to generate the linear elements from the edges of the buffer layer rather than the original shapefile. The Buffer tools of QGIS or ArcGIS software can for example be used to generate the desired buffers.

Generating the screen ¶

Here, as for generating the nets, a mesh is generated from the polylines to create the screen. The latter is then converted into points, downsampled with a spacing of about half a diameter d1 from the smallest rocks to be simulated. A negative vertical translation of the screen is applied to ensure that the latter intercepts the ground. This is not necessary if the polygonal lines making up the base of the screen have previously been projected onto the ground.

Last requirements ¶

Finally, we must ensure that we only have the position of the points for the Infrastructures / collectors: [X, Y, Z].

Any [R, G, B] colors, surface orientation [Nx, Ny, Nz] and scalar fields must be removed before exporting the grid points in ASCII format.

The ASCII file must be named "infrastructure.txt" or "infrastructures.txt" in order to be correctly taken into account when importing the terrain for simulations.

Infrastructures from LiDAR ¶

This step is very similar to that of preparing the terrain. The infrastructure points are extracted from Airborn LiDAR (ALS) data based on their classification. These are then interpolated in order to fill the holes and to generating the walls.

Extracting the relevant elements ¶

This short step takes over the concepts used to prepare the terrain or the tree stems, using the classification of ALS points to extract the elements of interest. To do this, the Scalar fields / Filter by Value tool is used.

Generating the walls ¶

Here, the walls of the infrastructure are filled in using the technique used to fill in the holes during the preparation of the terrain. The terrain and infrastructure points are however colored differently in order to be able to isolate the infrastructures from the ground.

Last requirements ¶

Finally, we must ensure that we only have the position of the points for the infrastructures: [X, Y, Z].

Any [R, G, B] colors, surface orientation [Nx, Ny, Nz] and scalar fields must be removed before exporting the grid points in ASCII format.

The ASCII file must be named "infrastructure.txt" or "infrastructures.txt" in order to be correctly taken into account when importing the terrain for simulations.