How to create a TIN from 2D contours?

I was given a 2D DGN with contour lines that were created from LIDAR data.  The contour lines have an attribute assigned to them called "CONTOUR" with the elevation.  We would like to merge this information into a 3D DGN so we can create a TIN/DTM surface.  How do I do this?

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  • Well, the first thing I would do is see if the original LIDAR data is available. Building a surface from contours is fraught with issues. I always quote an old POB magazine article, "Contours are output, not input!" when this question gets raised. You will get significant flat areas based upon the image you posted.

    I suspect that this data may have originated as a shape file as DGN elements do not generally have fields. There are posts or documents explaining how to get MicroStation to read a shape file and create 3D using a field value for the Z value, but these are for SHP files, not DGN files.

    It's possible a VBA macro could be written, but that assumes the field can be exposed to the VB project, which may be a heavy lift. 


    Charles (Chuck) Rheault
    CADD Manager

    MDOT State Highway Administration

    • MicroStation user since IGDS, InRoads user since TDP.
    • AutoCAD, Land Desktop and Civil 3D, off and on since 1996
  • Thanks for the reply.  We received the DGN file from our client and it appears to be created from a shapefile.  Not sure of their understanding of CAD so they likely thought this was what we wanted when requesting any surface information.  I sent a request for the shapefile or lidar data used to create this DGN.  I just wanted to research if there was another way to go about it that I wasn't familiar with.  Thanks for the help! 

  • There used to be a PDF, but I did find a video: https://www.youtube.com/watch?v=2JFqM3ba-8c

    It is using a Pre-CE version of the product. I assume the workflow still exists, but might need different access points to the tools.


    Charles (Chuck) Rheault
    CADD Manager

    MDOT State Highway Administration

    • MicroStation user since IGDS, InRoads user since TDP.
    • AutoCAD, Land Desktop and Civil 3D, off and on since 1996
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