Tutorial, welding for Pepakura.

Discussion in 'Software' started by wunwinglow, Apr 12, 2004.

  1. wunwinglow

    wunwinglow Active Member

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    I am using Rhino as my 3D modelling tool, but the problem being tackled in this Mini Tutorial may crop up in any modelling package. You have modelled your component, imported it into Pepakura and THIS happens!

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    Each surface is seperated from its neighbours, and no amount of clicking on the knife and sticky tape tool has any effect. What has happened? If you can interrogate the part properties, you will find the box has 24 vertices, rather than the 8 you might expect. Each corner has 3 vertices all in the same place, one from each of the box sides.

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    We must use a process called 'Welding', which will solve this problem. In Rhino first you must import the mesh model, in this case it is an .obj file, (so this will be in addition to your original NURBS model), select it and use the WELD tool, which is on the Mesh Tools toolbar.

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    A tolerence parameter is then requested and this refers to the angle between adjacent triangles where they meet. All our box corners are at 90 degrees, so any value higher will do; I used 91, but 100, or 179 would work as well. Set a lower number, say 89, and the vertices would be left seperated; not what we want!

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    A quick check, by selecting a corner node now shows only 1 vertex instead of 3, so if we export this mesh, it should work in Pepakura.

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    And so it does....

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    Rhino has a lot of settings and controls associated with mesh generation, and other 3D modelling packages have other similar, and some much more sophisticated controls.

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    But remember, for Pepakura to work well, it needs a fairly simple structure, with all the vertices welded.

    Next time, we'll look at altering the way Pepakura breaks up a mesh.

    Feedback always welcome!
    Tim
  2. NOBI

    NOBI Active Member

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    Hi Tim,

    Incredible again. this tutorial can answer all question about why unfold model in pepakura and result is in thousand of triangle :) in Metaseq call join vertex together, u can join vertexs into vertex like weld it together in Rhino but not use many step like Rhino did ;) only crop vertex u want to join and press Ctrl+J
  3. wunwinglow

    wunwinglow Active Member

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    Hi NOBI, you are correct, most mesh modelling programs have welding controls built in. It is a basic control for such models. But sometimes you forget, and it is a surprise when Pepakura explodes your model like this!

    As you know I use Rhino a lot, but it is a NURBS modeller. Even so, it has the controls to correct this problem.

    I hope to do some more mini-tutorials; what subjects would be useful?

    Tim