Need help with SketchUp obj to stl

Discussion in 'Software and Applications' started by lensman, Aug 11, 2012.

  1. lensman
    lensman Well-Known Member
    I rarely use SketchUp for modeling but have recently tried it again. I essentially have a model which is a column of varying widths. Down the centre of the column is a hole - in the middle the width of the hole changes.

    I can export the model in OBJ format and import into Rhino or MiniMagics where it looks fine, however, when I export as an STL from Rhino and upload to Shapeways the hole down the middle of the column is completely closed in (the faces on either end of the column are solid).

    Even uploading as an OBJ from SketchUp produces the same result.

    Why, then does the model look as it should in Rhino or MiniMagics, and Meshlab?

  2. stop4stuff
    stop4stuff Well-Known Member
    I'm having a half guess here, but my guess is based on looking at sketchup models, it has something to do with how the normals are applied to create mesh psuedo boolean additions or subtractions 'on-the-fly' for visual effects.

    How does the model look if you export as an stl from MeshLab and load it into NetFabb?

  3. Fredd
    Fredd New Member
    It could possibly be ngons causing the problems. Mesh lab allows some really complicated mesh techniques, while netfabb has a hissy fit if it detects anything wrong.(similar to SW's rejection mode.)
  4. lensman
    lensman Well-Known Member
    @shop4stuff - In Netfabb although the whole geometry looks funky (lots of triangles) at least the hole is there.

    @Fredd - Yeah, now I remember why I gave up modelling with SketchUp; things look fine in the programme but in reality there can be mega problems with flipped normals and messy geometry...

  5. denali3ddesign
    denali3ddesign New Member
  6. lensman
    lensman Well-Known Member
    Thanks, Marcus. I have a plug-in in SketchUp for this (discovered after my first post!) but even that fails. I think it is inherent problems with the geometry, really. While building the column I did a lot of pulling of the outside edge of the circle making it smaller or larger (with the damn tool I can't remember the name of now and don't have SketchUp on this computer) before building the column higher. I'm sure that had something to do with it.

    I tried a simple test with a plain column with a hole through the length and that worked fine.

    I've moved on to modeling it in another programme now...

    SketchUp models look great and the programme is relatively nice to use, but unless you are very careful you can end up with a real mess in the geometry.

  7. denali3ddesign
    denali3ddesign New Member
    Yeah, its easy to make a mess if you're not familiar with the program.

    Can you share an image of the column you were trying to make?

  8. lensman
    lensman Well-Known Member
    Here is the "column" now modelled in another programme.

    plastic stopper.jpg

  9. MobiusMagnetic
    MobiusMagnetic New Member
    Hi, I am new to shapeways, I am also using SketchUp 8, this plugin looks great but it trys to install default IE pages and other software that I do not trust. SketchUp Pro will allow these conversions out of the box. I am going to download the trial version to see if it works better, I am having similar issues.
  10. beagley
    beagley New Member
    Hi! Could you report back RE Sketchup Pro's export to STL? Curious.
  11. denali3ddesign
    denali3ddesign New Member
    Sketchup Pro doesn't export STL without a plugin.

    I use this plugin - it works with either the free or Pro version of Sketchup: p-skp-files-dxf-or-stl

    I haven't had any trouble with it installing anything extra - if you're getting extra stuff, look over the installation instructions just down a ways on the page.

    Hope that helps!
    Last edited: Oct 3, 2012