How to Work with Point Clouds in BricsCAD

Quick answer: BricsCAD pre-processes point clouds into a local cache, then offers tools to align, view, snap to, and extract 3D geometry from them, planes, cylinders, floors, and walls among them.

Pre-Processing a Point Cloud

Run POINTCLOUDREFERENCE to open the Point Cloud Cache Manager, then choose Process a file or Process a folder (POINTCLOUDATTACH works too). You can start this from a saved or unsaved DWG file, and you’ll be asked for the input point cloud, no units or insertion point needed yet.

All the data gets read, processed, and written to disk, with a log file created and progress tracked in the Cache Manager dialog. Pre-processing happens in two steps: processing the points, then visual optimization.

Some unusual files, like LAS files with a non-standard column layout or geo tags, don’t pre-process correctly on their own. A separate shell executable, preprocessor.exe, in the BricsCAD installation folder lets you specify non-standard layouts or geo tags manually (using -w skip); run it without arguments in a shell for a usage summary.

Bubbles and Background Processing

Point cloud files and 360 images become available in the drawing almost instantly, showing as purple bubbles at first, since they don’t yet have normals or depth information per point. Background processing continues until that information is ready, at which point the bubbles turn green.

Progress is logged in a subfolder related to the point cloud, inside the current cache path set by POINTCLOUDCACHEFOLDER (defaulting to C:\Users\%username%\AppData\Roaming\Bricsys\BricsCAD\V26x64\en_US\PointCloudCache). The log is mainly for troubleshooting; the Cache Manager dialog is the better place to watch progress directly.

Managing Pre-Processed Point Clouds

The Point Cloud Cache Manager lets you search or filter cached point clouds, view all available metadata for a selected one in its Details section, and edit its data name, unit, and GIS coordinate system.

Cache subfolders processed elsewhere, another BricsCAD cache folder or the shell preprocessor, can be copied directly into the folder set by POINTCLOUDCACHEFOLDER and will show up the next time you open the dialog. If an HSPC cache can’t be found where expected, a tray notification redirects you to the Attachments panel to point it at a new cache folder.

Attaching a Point Cloud

Click Attach to open the Attach Point Cloud dialog, where you set the insertion point, scale, rotation, unit, and GIS coordinate system for that instance, and optionally choose to use its geo data if available.

Aligning a Point Cloud

POINTCLOUDALIGN automatically rotates a point cloud to align with the X and Y axes, based on its vertical planar surfaces, walls, for example. You’ll be asked to specify the most relevant wall-containing area to base the alignment on.

The Bubble Viewer

Depending on the file format and scanner type, scan locations show as bubbles (green spheres) or waypoints (blue spheres). LAS and PTS formats don’t contain scanner information, so they can’t produce bubbles at all.

• Structured data (static scanners): the scanner’s location is known for every point, producing bubbles with real depth information, usable for algorithms like planar fit and cylinder fit.
• Unstructured data (kinematic scanners): no exact scan location per point; panoramic images at intervals instead produce waypoints, which have no depth information and are for visualization only.

Open the Bubble Viewer by running POINTCLOUDBUBBLEVIEWER and specifying a bubble index, double-clicking a bubble in model space, or choosing “Open scan in bubble viewer” from a scan or waypoint’s context menu in the Point Cloud Manager panel.

Inside the viewer: hold the middle mouse button and move to look around, scroll to zoom, and press Tab to cycle through three visual modes, colours (or greyscale depth), normals (coloured by UCS axis direction), and distances (light to dark based on distance from the scan). Nearby scans show as red bubbles; hover to see a scan’s name, double-click to switch to it. Press Ctrl+A to sync the drawing view to match the Bubble Viewer. While a command prompts for a point, you can also use the Bubble Viewer to snap directly to point cloud points.

The Point Cloud Nearest Point Entity Snap

PCNEAREST (bitcode 128 of 3DOSMODE) significantly improves selecting relevant points in a point cloud. It works by projecting an imaginary cylinder from your current viewpoint toward the cursor, with a radius set by the Entity snap aperture box (APBOX), and returns whichever point inside that cylinder is closest to the camera.

Turn it on alongside your other 3D entity snaps in the snap menus, toolbar, or settings, and make sure bitcode 1 of 3DOSMODE (“Turn off all 3D snaps”) is unticked, otherwise it won’t work regardless of this setting.

Exporting a Point Cloud

POINTCLOUDEXPORT exports the currently visible parts of a point cloud to a PTS, HSPC, or LAZ file.

Detecting Floors

POINTCLOUDDETECTFLOORS detects floors in a building’s point cloud based on regions of similar Z-coordinates, helping you navigate large building scans. For better results, hide anything unrelated to the building first, using POINTCLOUDCROP, POINTCLOUDREGION, POINTCLOUDCLASSIFY, or by turning off irrelevant classes in the Point Cloud Manager panel. This command is also a step in BricsCAD’s Scan to BIM workflow.

Point Cloud Projection

POINTCLOUDPROJECTSECTION detects walls from a volume section of a point cloud (created with BIMSECTION) using a variety of wall detection options, generating 2D lines for a floor plan or vertical section. It runs as a background process, and multiple sections can queue up, letting you process everything at full resolution. It also generates a raster image alongside the geometry for context, useful for verifying the result, or even as graphical material in its own right, for example as a background image in a BIM renovation project.

Fitting a Planar Surface or Solid

POINTCLOUDFITPLANAR creates a planar surface or solid from a seed point you select, using a threshold value (a property of the point cloud entity) to determine which nearby points count as being on the same plane. Hold Shift and select adjacent walls to extend or trim the fitted planes into a closed surface. Select openings accounts for door and window openings (Bubble Viewer only), Adjust borders lets you tweak the planar border contour, and Stitch surfaces combines multiple fitted planes into, for example, a single solid usable later with BIMINVERTSPACES.

In the Bubble Viewer: select seed points there directly; the cursor previews the plane’s normal direction, and you get a preview in both the Bubble Viewer and model view, toggle between the two with Ctrl. Points being considered show in purple, turning green once you accept the result.

In model space (Bubble Viewer closed): select a point cloud point directly. This can take longer depending on how much of the point cloud is visible, but has two advantages: it can build larger surfaces by combining parts from different scans, and it can detect wall and slab thickness.

A typical workflow: convert a point cloud into stitched POINTCLOUDFITPLANAR results, one solid per room, then run BIMINVERTSPACES to invert those temporary room solids into an actual building model with walls and slabs.

Fitting a Cylinder

POINTCLOUDFITCYLINDER, used inside the Bubble Viewer, fits a cylinder to cylindrical parts of a point cloud, pipes, for example. Two clicks along the cylinder’s axis in the viewer extract it as a solid in model space.

Visualizing Deviation

POINTCLOUDDEVIATION visually assesses how well a planar structure fits the point cloud around it, using a colour map: green means planar (a good fit), shifting toward blue means further above the plane, and shifting toward red means further below it. A summary also shows what percentage of points fall into each category (OK, warning level, and so on).

Frequently Asked Questions

Why do some point clouds show bubbles while others show waypoints instead? It depends on the scanner type. Static scanners produce bubbles with real depth information; kinematic scanners produce waypoints from panoramic images, which have no depth and are for visualization only.

Why isn’t the Point Cloud Nearest Point entity snap working even though I’ve turned it on? Check that bitcode 1 of 3DOSMODE (“Turn off all 3D snaps”) is unticked, it overrides bitcode 128 regardless of that setting.

What’s the advantage of using Planar Fit in model space instead of the Bubble Viewer? It can combine parts from different scans into larger surfaces, and can detect wall and slab thickness, something the Bubble Viewer mode can’t do.

Can I edit a point cloud’s metadata, like its unit or coordinate system, after pre-processing? Yes, in the Point Cloud Cache Manager’s Details section for that point cloud.