Working with Point Clouds

Pre-processing

To pre-process a point cloud, you can use the POINTCLOUDATTACH command or select Process a new scan in the Point Cloud Reference Manager, which can be accessed using POINTCLOUDREFERENCE command.

The progress of the pre-processing is recorded in a log file in the sub-folder related to the point cloud. This sub-folder is located inside the current point cloud cache path. The default path for the current point cloud cache is C:\Users\USERNAME\AppData\Roaming\Bricsys\BricsCAD\V23x64\en_US\PointCloudCache\Folder_for_processed_pointcloud, and can be set in the POINTCLOUDCACHEFOLDER system variable.

Note: The log file is mainly used for troubleshooting. You can follow the progress of the pre-processing in the Point Cloud Reference Manager.
Note: Some unusual point cloud input files, like LAS files with non-standard column layout or non-standard geo tags, are not automatically preprocessed correctly. However, there is also a shell executable pre-processor (preprocessor.exe) in the BricsCAD installation folder that allows to specify non-standard column layout and/or geo tags (-w skip). The shell pre-processor uses the same library under the hood, but it exposes some manual options that are not automatically used by BricsCAD. To learn about the options, run the pre-processor executable without arguments in an OS shell. A usage summary will be printed. For more detailed information see the How to use the preprocessor.exe in order to ignore GeoTIFF tags while preprocessing non standard .LAS, .LAZ pointcloud data?
Note: Any subfolder with previously pre-processed point cloud cache data (from another BricsCAD point cloud cache folder or preprocessed with the shell executable preprocessor.exe) can be copied in the folder specified by the POINTCLOUDCACHEFOLDER system variable (default value: C:\Users\USERNAME\AppData\Roaming\Bricsys\BricsCAD\V23x64\en_US\PointCloudCache) and will be available next time you will open the Point Cloud Reference Manager. For each subfolder in the point cloud cache folder, there is an item in the reference dialog box:

Alignment

The POINTCLOUDALIGN command automatically rotates a point cloud to optimally align it with the X and Y axis, taking into account the vertical planar surfaces in the point cloud (e.g. walls). To determine the best alignment, you will be asked to specify the most relevant area of the point cloud containing walls.

Bubble Viewer

Depending on the original file format of the point cloud and the type of scanner used during scanning, bubbles (green spheres) might be shown at all the scan locations.

At these locations, you will experience the most realistic visual representations by opening the bubble viewer.
Note: Point cloud bubbles are only created when points are scanned with static scanners and points are grouped per scanner location. LAS and PTS formats do not contain scanner information, so they cannot produce point cloud bubbles.

Indicate a bubble index in the POINTCLOUDBUBBLEVIEWER command or double-click one of the bubbles in model space to open the Bubble viewer. You can press and hold the middle mouse button and move the mouse to view the point cloud in any direction from that scan location. You can also zoom in and out using the mouse wheel.

Press the Tab key to cycle through three different visual modes.

The first mode displays the points as their actual colors or in grayscale, depending on how the data was scanned.

The second mode displays the points as red, green, or blue according to their normal vectors. The colors correspond to the UCS axes.

The third mode displays the points from light to dark as the distance from the scan location increases.
You can easily sync the drawing view to match the Bubble viewer by pressing Ctrl+A.
Note: You can turn off point cloud bubbles from Model Space and you can change their size in the Properties panel.
Note: During commands that prompt for selection of a point, e.g. (poly)lines, you can use the bubble viewer to snap to point cloud points.

Entity snaps

The Point Cloud Nearest Point entity snap significantly improves the ability to select relevant point cloud points. It uses an imaginary cylinder from the current viewpoint toward the cursor.
The radius of the imaginary cylinder is defined by the Entity snap aperture box setting.
Note: The result is the point inside the imaginary cylinder that is the closest to the camera.

Enable the new Point Cloud Nearest Point entity snap together with other 3D entity snaps in the Entity Snap menus, toolbar and settings.

Note: Make sure that only the 128 bitcode of the 3DOSMODE system variable is set. (Untick Turn off all 3D snaps).

Export

The POINTCLOUDEXPORT command allows you to export the visible parts of a point cloud to a PTS, HSPC, or LAZ file.

Floor Detection

The POINTCLOUDDETECTFLOORS command generates volume sections for each floor found in a point cloud of a building. The detection is based on regions of points with similar Z-coordinates. The generated volume sections can help in navigating point clouds of buildings.

Point cloud projection

The POINTCLOUDPROJECTSECTION command enables you to detect walls from the volume section of a point cloud based on a variety of wall detection options. You can create volume sections automatically for each floor in a building. You can use these sections to generate 2D lines to create a 2D floor-plan or a vertical section. This is a background process and multiple sections can be processed in a queue. This way, it is possible to run this command in full resolution on all sections.
At the same time, a raster image is generated to give the user some context. In some cases, it is not necessary to recreate the existing building. Background images can give much more context to the design documents. These can be used to verify the created 2D geometry but in high quality scans, these images can also be used as graphical material. For example, as a background image for a BIM model in renovation projects where modern intervention are made in historical buildings.

Planar Fit

The POINTCLOUDFITPLANAR command enables you to create 3D geometry based on the point cloud. It will create a planar surface or solid after selecting a seed point in a point cloud. To detect the points that lie on the same plane as the seed point, a threshold value is used that can be set as a property of the point cloud entity. By holding down the shift button and selecting the adjacent walls of a room, the fitted planes will be extended/trimmed to form a closed surface.

Note:
  • Select openings allows you to take into account the openings of doors and windows (only in bubble viewer).
  • Adjust borders allows you to adjust the planar border contour.
  • Stitch surfaces provides stitching the result of multiple fitted planes into, for example, a solid which can be later used with the BIMINVERTSPACE command.
In bubble view
If the bubble viewer is open when the command is launched, BricsCAD expects you to select the plane seed points inside the bubble viewer. The cursor will give you a preview of the normal direction of the plane. Next, you get a preview in both bubble viewer and model view. You can toggle between 2 shape representations using the CTRL key.
Note: While still in selecting mode, the corresponding points in bubble are shown in purple. These points are shown in green once the user accepts the generated result.




In model space
You can also use this command in the model space when the bubble viewer is not open. BricsCAD will ask you to select a point of the point cloud in model space. Depending on the size of the visible parts of the point cloud, this might take more time compared to running the command inside the bubble viewer. however, this has 2 advantages by searching multiple scan positions:
  • It can create larger surfaces by combining parts of different scans.
  • It can detect wall and slab thickness.




Note: Here, a work-flow of converting a scan to building model is provided. The point cloud (top image) is first converted to a set of solids, one per room, using stitched POINTCLOUDFITPLANAR results (middle image). The command BIMINVERTSPACES converts these temporary room solids into a building model with walls and slabs from the inversion of these solids.






Fit cylinder in bubbles

By using the POINTCLOUDFITCYLINDER command inside the bubble viewer, you can fit a cylinder to the cylindrical parts of a point cloud (e.g. pipes) Two clicks along the cylinder axis in the bubble viewer are needed to extract a cylinder (a solids is created in model view).


POINTCLOUDDEVIATION

  • The POINTCLOUDDEVIATION allows you to visually assess the fit between planar structures and points of the point cloud.

  • Point cloud section of floor of a house and a fitted plane:


    The distances of points from floor to the fitted plane are visualized using a colormap. In the left panel, an explanation of the colors is provided (green is planar, gradient from green to blue here is further above the plane, gradient from green to red is further below the plane). Also, a summary of the percentages of points in which category is presented (OK, warning level, …)