How do I thin out imported Cad pointclouds?

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How do I thin out imported Cad pointclouds?

Ville Ronkanen posted 05-21-2026 04:29

I have a large point cloud in dwg-format, that I need to import into TBC, and calculate grounds Contours out off. The data is from aerial laser scanning, so it is far too dense to get reasonable results with smooth lines at 1m intervals. The contours come out jagged and sharp because the original material is too dense.

How can you thin out the point cloud before calculating the Contours? For example, reading in only every third point, etc. For the life of me, I have not found tools in the program for this! Or do I need to convert the cad points first to something else, and do massive work arounds before calculating the contours?

M_ Hufford posted 05-21-2026 05:02

Have you tried Sample Region?

Ronny Schneider posted 05-21-2026 14:36

In order to do what M_Hufford suggested you'd need to import your cloud as "Pointcloud".

As long as I know TBC doesn't provide an easy way to convert drawing entities, CadPoints, into cloud points. It only offers Cloudpoints into CadPoints.

The only way I'd see in TBC is to export the CAD point coordinates into a text file that resembles closely the format of a PTS file. You probably still need to add the header line manually.

PTS import into TBC is super slow though, don't know what it is doing, i.e. 1 million points takes several minutes, I believe nearly 10 or thereabout.

See if you can convert your points into i.e. a LAS/LAZ or PTS file in another software, AutoCAD perhaps.

John Woodall posted 05-22-2026 07:20

Ville,

I am not sure if this will help you or not but I just watched a video by Robert Martin who is a Trimble rep here in the US that is a tutorial for creating grid points from a surface. Maybe you could use that method and create a second surface to generate the contours. I know it is a bulky work around but best shot i have for this.

Roberts video

text link in case the link above does not work --------- https://youtu.be/LwhIQ2jJrsA?si=kUZdqQaoVcVDR_n-

Zach Edwards posted 05-22-2026 07:23

Advanced filtering is another good one here if you are working with a ground region. It gets to the lowest point. Also, if you have the aerial survey licensing, you can try the extract ground tool. Extract Filtered Point Cloud Regions Based on Elevation & Extract Ground-Level Point Cloud Regions.

Frank Poetschke posted 05-22-2026 07:44

Maybe you have the chance to export the cad points into a pointlist in the format x y z, no pointnumbers and just space seprated. The call the extension .xyz pull it into TBC. TBC will import it als pointcloud and you can use the pointcloud functions and filter like descripted by others.

Frank

Trimble Business Center

How do I thin out imported Cad pointclouds?