As a result of multiple requests, here’s a quick guide on how to use point clouds in BricsCAD. In essence there are three steps:
- Preprocess the data
- Attach the data to a drawing
- Use the point cloud
The first step is data preparation. To navigate point clouds quickly data must be preprocessed (as already mentioned these files can really be huge). Use POINTCLOUDPREPROCESS to open a file dialog that lets you select input point clouds.
Currently, BricsCAD supports import of the following three types: .las, .pts, and .ptx (more formats will be added later). For information on where to find point cloud sources please see this blog post.
The next step is to select the name of the preprocessed output file. By default, the file dialog suggests the same name as the input file (without the numbers before the extension). The processed file is given the extension of .bpt (Bricsys Point Tree). However, you can change the name to anything you choose.
For AutoCAD® users: this whole step is the equivalent of creating a .rcp file in Recap.
2. Attach to a drawing
The next step is attaching the preprocessed .bpt file to the current .dwg. Use POINTCLOUDATTACH. A point cloud can NOT be attached to an empty template. The .dwg must be saved first. This is because the .dwg will then refer to the attached point cloud using a relative path from the location the .dwg file was saved.
When the .bpt file is selected, a dialog appears that lets you specify how to insert the point cloud into the drawing.
When the box “specify on screen” is checked, an insertion box will appear to let you determine translation/rotation/scaling (for all of which the box is checked). For the others, the values in the dialog will be used.
3. Use the .dwg with point cloud
Once the point cloud is attached, it can be manipulated like other entities. It can be moved/rotated/scaled, as with any other element. It also responds to the command SECTIONPLANE section planes, hiding parts outside section planes when these are active.
Note: A section plane has three states:
- Plane: clips everything away at one side of the plane
- Boundary: defines an infinite extrusion of the contour drawn onscreen
- Volume: is the same as the boundary above, but with a given top and bottom plane
When ESNAP is on, snapping to visible points in the cloud is also possible.
- Colormap (POINTCLOUDCOLORMAP): It doesn’t just have a cool icon! This nifty command means that false colors can be assigned to the points corresponding to intensity or elevation. Choose single spectrum colors such as red or blue, or go whole spectrum. The header image here uses “Earth” colors.
- Cropping (POINTCLOUDCROP): While a section plane crops everything in the scene, a point cloud crop is limited to the current point cloud, leaving other entities unaffected.
- Point Size (POINTCLOUDPOINTSIZE): Determines how large points are drawn onscreen. It can be useful to visually fill in gaps.
- Boundary (POINTCLOUDBOUNDARY): Choose to show or hide a point cloud bounding box.
Great news: if you, or someone you work with use AutoCAD® and Recap, it is possible to put the Recap preprocessed file in the same location with the same name as our .bpt file. The extension will be .bpt not .rcp. AutoCAD® can open and use the .dwg with the same point cloud, clippings and other entities present in the drawing.
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