Working with Point Clouds

Pre-processing

When you attach a point cloud that requires pre-processing, it converts 5 to 8 times faster in BricsCAD® V22 compared to V21.

To pre-process a point cloud, you can use the POINTCLOUDATTACH command or Point Cloud Reference Manager which is opened with POINTCLOUDREFERENCE command.

You can find the log file in C:\Users\USERNAME\AppData\Roaming\Bricsys\BricsCAD\V22x64\en_US\PointCloudCache\Folder_for_processed_pointcloud, only if this path is set in the POINTCLOUDCACHEFOLDER system variable. Inside this folder, you can view the current state of processing.

Note: The log file is more useful for troubleshooting, while Point Cloud Reference Manager is the dedicated location to monitor pre-process progress.
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\V22x64\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 (the points must be in vertical planes (e.g. walls). To determine the best alignment, it can analyze the entire point cloud, or you can specify the most relevant area.

Bubble Viewer

The point cloud displays bubbles at all the scan locations if:

  1. the data was captured from a set of fixed scan positions (stand somewhere fixed and capture millions of scanned points from a single origin scanner location);
  2. the data format allows to store that info.
In these locations, you will experience the most realistic visual representations.

Example of situation when either (1) or (2) is not satisfied:

  • Mobile mapping (scanning for example while walking around, or from airplanes) has no fixed scan positions, thus has no bubbles.
  • Also certain file formats like las have no possibility to store scan positions, even when the data was captured from fixed scan positions. So then also no bubbles can be created
Note: Point cloud bubbles are only created when points are scanned with static scanners and points are grouped per scanner location. LAS and PTS files do not contain scanner information, so they cannot produce point cloud bubbles.
Double-click one of the bubbles in model space to open the Bubble viewer. You can press 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 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.

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 in 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.

Export

The POINTCLOUDEXPORT command allows you to export a cropped selection of a point cloud to a PTS file.

Floor Detection

SectionPlanes work on point clouds as well. You can use them to show parts of point clouds. The difference between point cloud crops and SectionPlanes is that point cloud crop only clips the point cloud while section planes clip all geometry in your drawing.

The POINTCLOUDDETECTFLOORS command generates volume sections for each floor found in a point cloud representing 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 floorplan 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 one point in a point cloud. The points that seem to be in a plane are never exactly in one plane, therefore a threshold value is set as a property of the point cloud entity. This also works in bubble view.

Note:
  • Select openings allows to take into account the openings of doors and windows.
  • Adjust borders allows 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 before launching the command, BricsCAD® expects you to select plane seed points in 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 view 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 cropped point cloud, it takes more time, but it has 2 advantages by searching multiple scan positions:
  • It can create larger surfaces where only parts are visible in each scan position.
  • It can detect wall and slab thickness since it can take the opposite surface into account.




Note:
  • Workflow in which a point cloud (top image) is first converted to a set of solids, one per room, using stitched fitplanar 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.






  • Fitplanar in bubbles allows you to add openings (doors, windows), and adjust the resulting contour.
  • You can use bubbles to use snap points to draw things like (poly)lines.
  • Fit cylinder in bubbles:

    Bubble view window on the right, model space on the left. Two clicks along the cylinder axis in bubble space are needed to extract a cylinder (results as solids in model space). This is a first version of the algorithm, and will be made more robust in the near future.



  • 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:


    Visualization of distances of points from floor plane. 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, …)