Drawing a BIM Slab using Point Cloud

AlexRich
AlexRich
in BricsCAD BIM
I'm trying to model a basic 3D model of my point cloud, no building is ever built perfectly square yet it seems like I'm forced to draw the slab as a perfect square.

I use the polysolids to draw the walls at the real world angles but I can't work out the slabs.

Comments

  • Piet
    Piet
    hi,
    Do you have a BIM license or pro?
    In BIM there is the POINTCLOUDFITPLANAR command that will best fit planes to the point cloud. Or you can try the automated tools:
    https://help.bricsys.com/en-us/document/bricscad/point-cloud/point-cloud-scan-to-bim-workflow?version=V24&id=169103952811

    In pro you can use any traditional modeling tools. e.g. draw a polyline in any shape and extrude it.
  • reetie
    reetie

    You’re not missing anything obvious — most BIM/CAD tools do try to force slabs into “clean” orthogonal geometry, which doesn’t match reality from point clouds.

    The trick is: don’t start the slab as a square/rectangle.

    Instead, trace the actual slab perimeter directly from the point cloud:

    • Switch to a plan or section slice at slab level
    • Use a polyline (or sketch mode) and snap along the scanned slab edges, even if they’re slightly skewed
    • Then convert that polyline into a slab (or edit the slab boundary and replace it with the traced outline)

    If your software supports it, edit slab boundaries rather than creating a new slab from scratch. That keeps the irregular geometry without fighting the tool.

    Real-world scans = imperfect geometry. Your slab should follow the scan, not the grid.