Global Mapper v26.0

3D TIN Mesh

MartecA
MartecA
in Vector Data

Hi all. I don't normally have much luck in attracting a reply but we'll have another go.

Can anybody advise if it is possible to create a 3D TIN rather than square grids? My clients specifically want a triangle grid. I've been using Virtual Surveyor to do this as they have a very good workflow but I'm sure it can also be done in GM.

Seeking to simply create a triangulated irregular mesh from a DEM.

Many thanks.

Answers

  • DerrickW
    DerrickW
    Answer ✓

    You can export out to a TIN using LandXML.

    image.png
    image.png


    The example above is just exporting some data from the National Elevation Dataset directly to LandXML. If you're creating your own, you can check the box to "Save TIN" when creating a surface and then export that TIN out to LandXML (Look at the check boxes I have selected).

    image.png


    image.png


  • DerrickW
    DerrickW

    FYI - I'd recommend keeping your LandXML surfaces under 10mb, ideally under 5mb. CAD doesn't deal with very high resolution surfaces very well.

  • MartecA
    MartecA

    Thankyou Derrick for taking the time to respond. Many thanks.

  • MartecA
    MartecA

    Hi Derrick. Ive tried this with a DEM of my own and the global elevation data and managed to only export a blank file. I must be doing something wrong. Ive done the follwoing,

    1. Open DEM
    2. Create an area feature
    3. Highlight the area feature
    4. Select File>Export>Export Vector/Lidar Format>LandXML file>Selected TIN and Crop to Area Feature

    Ive tried it multiple times and keep getting an empty file.

  • DerrickW
    DerrickW

    Sorry I never saw this reply before today. Did you get this resolved?


    Any chance you're exporting an area smaller than the source data's sampling grid (allowing 3+ elevation points to fall within the export area)?

  • gnicholas
    gnicholas

    This is a problem for us as well. We have to use Arcmap to create a TIN from a DEM right now. What global mapper is creating is NOT a TIN. TIN stands for triangulated irregular network. Key word there is irregular. If given a DEM, global mapper just spits out a REGULAR network of triangles, which is not very useful if the idea is to go to autocad with the TIN. The whole point of a TIN is to reduce the size of the data, adding triangles where more information is needed, and reducing triangles where slope is constant, and more triangles are not needed to accurately depict the surface. This is, for us as surveyors, one of the biggest issues with global mapper.

  • bmg_mike
    bmg_mike Global Mapper Guru Moderator, Trusted User

    There is a method inside GM to create a simplified triangular mesh from any loaded terrain. You simply right-click on the terrain layer in the Control Center, then select the Layer -> Create Mesh Features from Terrain menu command to create a triangular mesh at a specified base resolution with simplification optionally provided.

    You can then export that simplified mesh to a TIN vector format, or the right-click Layer menu on the new mesh layer has an option to create 3D areas from each triangle, which is a TIN layer.

    Thanks,

    Mike

    Global Mapper Guru

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