Creating a Tin surface from point cloud - workflow and optimisations

fegis
fegis
in 3D Modeling

Hi all,

I am using BricsCAD v21 with an attached e57 point cloud.
I want to create a TIN of the floor & walls. It's a saw cut rockface.

Crop point cloud (e57) to relevant areas.
Export as PTX
Import PTX point cloud
Create TIN

The TIN feels very laggy. DWG is 1gig now. with wits of triangles. Is there a way to reduce the triangles or make it more efficient as I dont need it so detailed?

Many thanks in advance for help
-Fegis

Comments

  • ALANH
    ALANH
    edited February 2021

    Every one thinks that point clouds are going to be great and they are but at the expense of the volume of points, a field survey maybe 500 points a point cloud maybe 500,000.

    You can thin point clouds like removing every second point. There is software out there but you may have to pay for it.

    If the cloud is a grid style then it may be feasible to create a new point file with a larger spacing based on the surface and use that say in another dwg.

  • AndrejKogovsek
    AndrejKogovsek

    Hello

    Filtering of points from a point cloud or large XYZ file before creating a TIN surface is under development and will be available in future releases. Point removal criteria will be available to remove unnecessary points.

    In BricsCAD V21 there is an option to create TIN surface within selected polygon, source data outside clip polygon is ignored. Run TIN command and enter "cLip" when creating TIN from various sources (file, point cloud, drawing entities). It could be useful in some cases or to simplify TIN creation workflow.

    Kind regards,
    Andrej

  • James Maeding
    James Maeding

    Uh, filtering of the original point cloud is not the right solution.
    It used to be, but what you want is something that gives you the closest shape to full use of the points, assuming the points are already cleaned up from original scan method.
    I'm a .net and below language person, so can't make use of c++ libraries.
    There is a .net one called geometry3Sharp at:
    https://nuget.org/packages/geometry3Sharp
    Which I implemented into our civil engineering tools to take drone point clouds to a TIN of any size.
    The part it does is simplify a TIN surface. The Unity gaming engine crowd use it a lot too.
    I typically feed it 20 million point .laz files and ask for 500k tri surfaces.
    I do that by dividing up the point cloud to chunks of 400,000 pts, making a full tin surface of each, simplifying each way down, then adding back together. Its all multi threaded btw, like watching a stadium stand to their feet when watching the cpu's in task manager!
    None of that is easy to implement as the data is heavy and points in .laz are typically random, not sorted.
    Anyway, it works. My 16 core machine takes about a minute or two on a 20 mil point cloud.
    Use that free geometry3Sharp library and Bob's your uncle. (well, I actually do have an Uncle Bob so he is always my uncle...)