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I would like to convert a very easy(examplary) mesh(2D) 

Needs["NDSolve`FEM`"]
ToElementMesh["Coordinates" -> -{{0, 0}, {1, -.5}, {0.7, .8}, {0, 1}},
"MeshElements" -> {TriangleElement[{{1, 2, 3}, {1, 3, 4}}]}, 
"BoundaryElements" -> {LineElement[{{1, 2}, {2, 3}, {3, 4}, {4,1}}]},
"PointElements" -> {PointElement[{{1}, {2}, {3}, \{4}}]}]["Wireframe"]

enter image description here

by changing the Coordinates(2D-3D) and assuming the 3Dmesh to be a boundary mesh:

ToBoundaryMesh[
"Coordinates" ->Map[{#[[1]], #[[2]], RandomReal[]} &, {{0,0}, {1, -.5}, {0.7, .8}, {0, 1}}],
"MeshElements" -> {TriangleElement[{{1, 2, 3}, {1, 3, 4}}]}, 
"BoundaryElements" -> {LineElement[{{1, 2}, {2, 3}, {3, 4}, {4,1}}]} 
]["Wireframe"]

MMA evaluates the expression without error bur doesn't show the mesh!

What's going wrong here? Thanks

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  • 2
    $\begingroup$ For 3D ToBoundaryMesh[rules] syntax you should pass surface elements to "BoundaryElements" rule and set "MeshElements"->Automatic. $\endgroup$
    – Pinti
    Oct 16, 2018 at 11:09
  • $\begingroup$ @Pinti Thank you, ToBoundaryMesh[ "Coordinates" -> Map[{#[[1]], #[[2]], RandomReal[]} &, {{0, 0}, {1, -.5}, {0.7, .8}, {0, 1}}], "BoundaryElements" -> {TriangleElement[{{1, 2, 3}, {1, 3, 4}}]}]["Wireframe"] works without MeshElement! $\endgroup$
    – Ulrich Neumann
    Oct 16, 2018 at 11:13

1 Answer 1

Reset to default
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To not leave this unanswered:

ToBoundaryMesh[
  "Coordinates" -> 
   Map[{#[[1]], #[[2]], RandomReal[]} &, {{0, 
      0}, {1, -.5}, {0.7, .8}, {0, 1}}], 
  "BoundaryElements" -> {TriangleElement[{{1, 2, 3}, {1, 3, 4}}]}][
 "Wireframe"[Boxed -> True]]

enter image description here

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  • $\begingroup$ @ user21 Thank you! $\endgroup$
    – Ulrich Neumann
    Apr 19, 2019 at 12:41

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