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TIN Not Creating Correctly

  • August 25, 2025
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james_c_452
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Hi,

I’m having a issue making a TIN properly in FME. Basically FME is interpolating points/vertexes that don’t actually exist in the original data. What I want to do is make a TIN that considers only the vertexes of the features I give to it (point/lines and breaklines). I do not want FME to make up data that does not exist.

Does anyone know a way that I can do this?

For example in this example this is one break line. It should only have two TIN vertices (the ends). No triangles should be created from any interpolated points

 

However, when I look at the TIN for the same spot it has created 6 vertices

 

I am using FME workbench/form 2023. I’ve been trying different settings for the SurfaceModeller and the TIN generator

Best answer by hkingsbury

How is your TINGenerator configured?

If I set it to ‘Preserve Breakline Edges’ I get this result:

 

If I set it to ‘Preserver Delaunay by Adding Points’ I get this:

 

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    4 replies

    hkingsbury
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    • hkingsburyCelebrity
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    • August 25, 2025

    My understanding of a breakline (this may not be 100% correct) is that it’s used to force a continuous edge in the output. Therefore it makes sense that its adding vertices there to enforce the creation of that edge.

    https://desktop.arcgis.com/en/arcmap/latest/extensions/3d-analyst/breaklines-in-surface-modeling.htm

     

     

    james_c_452
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    • james_c_452Enthusiast
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    • August 25, 2025

    Hi ​@hkingsbury ,

    That’s what FME seems to be doing (adding the vertices). For topographical surveys we don’t want it to do that. There a break line forces a triangle edge (So it stops any triangles forming over it and does not make any new nodes. It only uses vertexes that actually exist)

    So in your example nodes 12/23/37 would not exist. The result I want would look like this

     

    hkingsbury
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    • hkingsburyCelebrity
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    • August 26, 2025

    How is your TINGenerator configured?

    If I set it to ‘Preserve Breakline Edges’ I get this result:

     

    If I set it to ‘Preserver Delaunay by Adding Points’ I get this:

     

    james_c_452
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    • james_c_452Enthusiast
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    • August 27, 2025

    Hi ​@hkingsbury, that’s more what I’m after. However, I don’t have that option. I my original post I mentioned I was using v2023. I’m limited to this at the moment until my company’s server/flow is updated.

    I see that the option you are demonstrating is in v2024 though. So I guess I will have to wait to use this function online. 

    Thanks
     

     

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