Snap to elevation inside TIN triangles

George1
George1
in 3D Modeling

I want to draw lines or 3Dpolylines on a TIN surface. The lines/polylines should have at their endpoints/nodes the elevations from the TIN. Is it possible to snap to the elevation of the TIN below the mouse cursor? Snap seems to work only at the TIN triangles edge lines, but I want to place entities at random places that fall inside the triangles.

P.S. I know I can use TINPROJECT to draw the lines/polylines and then get the elevations from the TIN. But I prefer to get elevations as I draw and not afterwards.

Comments

  • Virgil
    Virgil

    Hello.

    Snapping to a triangular face of a TIN surface is not possible, even when using 3D snap options.

    TINPROJECT is, indeed, an alternative.

    Another alternative, if you use V25, could be to use a String entity.
    https://help.bricsys.com/en-us/document/command-reference/s/string-command?version=V25&id=172017394110

    A String entity is a 3D polyline that can have civil data attached.

    The approach of using a String, is to work using a plan (top) view and pick some points to define the entity.
    After picking a point, its elevation is required.
    One of the options is to use a TIN surface and get the elevation from it.

    The command prompt is like this:

    : _string
    Specify start point: <pick point>
    Specify elevation or [Surface] <0>: s
    Select TIN Surface [selection options (?)]: <select TIN>
    Specify elevation or [Surface] <3595.53>: <press ENTER to accept the elevation from TIN>
    Specify next point or [Arc]: <pick point>
    Specify elevation or [Surface/Difference/sLope/Grade] <0>: s
    Specify elevation or [Surface/Difference/sLope/Grade] <3580>: <press ENTER>
    Specify next point or [Arc]: <pick point>
    ...

  • andrejm
    andrejm

    Just want to add a small remark, it is possible to 'snap' to the elevation of the triangle via 'nearest' snap. In wireframe mode it will only snap to the vertices and edges of the triangles, but if you use a draw mode where the faces of the triangles are also visible (e.g. SHADEMODE → Realistic) you can also get the elevation at any point on the TIN Surface.

  • Sakko
    Sakko

    Great undocumented feature, at least for me ….!!!!

    image.png
    image.png

  • Tom Foster
    Tom Foster
    edited October 30

    andrejm:

    if you use a draw mode where the faces of the triangles are also visible
    (e.g. SHADEMODE → Realistic) you can also get the elevation at any
    point on the TIN Surface

    Wow - does this also work for Surfaces e.g. a Lofted surface?

  • andrejm
    andrejm

    @Tom Foster yes, I think it should work, it just needs some small adjustments. You should enable 3d entity snaps and then have the 'Nearest to face' option selected (again in the correct SHADEMODE). I think this achieves similar results for solids and surfaces.

  • Tom Foster
    Tom Foster

    That would have saved me many repetions of a multi-step workaround lately! thanks.