Create thin walled model of the Stanford Bunny

Discussion in '3D Design Requests' started by Martin_, Apr 1, 2012.

  1. Martin_
    Martin_ New Member

    I need to print out the Stanford Bunny

    There are some holes in the downloadable model there. So I borrowed Geomagic Studio from the university and closed the holes and converted the data into a stp file for further processing in Catia V5.

    The problem is that the created model is a solid. By this I mean that the whole volume is filled with material. And since shapeways charges for printed volume this would become quite expensive. Therefore I would like to create a thin wall (about 2mm) into the inside-direction from the surface. I can then put a hole inside later on so the material can be removed.

    Catia can do this with some surface patches but crashes for others. I wanted to ask you if you know a program that can do this operation or if you have the program to try it out for me.

    I attached a stp file. If you need any other file formats I should be able to convert it with my programs (stl, ply, igs, ...)

    EDIT: I removed the zip file because it didn't work.

    thank you
    Last edited: Apr 3, 2012
  2. stop4stuff
    stop4stuff Well-Known Member
    Hi Martin,

    Welcome to Shapeways! :)

    I tried downloading your file, but I get an error when trying to unpack the zip :(

    Anyhow, the following info was posted by dizingof a while back and I can't find his post now.

    Grab yourself a copy of Mesh Lab (free) and load your model in. Then follow the method below.

    -> Filters (on menu bar)
    ->Remeshing, simplification & reconstruction
    -> Uniform Mesh Resampling

    check Absolute Distance
    Precision - the smaller the number the finer the mesh
    Offset - if your model is built using the basis of one unit = 1mm, then enter the thickness you require in the world unit box, otherwise you'll need to figure out the thickness as a percentage of the model size.

    Click apply

    Open the layers dialog pane (View -> Show layers dialog) and select the new 'Offset Mesh'

    The offset mesh consists of two shells, inner and outer copies of your original mesh, save the offset mesh (File -> Export Mesh As) for clean up and use in your modelling software.

    If you're still stuck, email me the file to paul[at]stop4stuff[dot]com

  3. Martin_
    Martin_ New Member
    Hi Paul,

    thank you very much for your quick answer. I found the post from dizingof you mentioned 5&&srch=resampling#msg_41195

    I have already done some stuff in meshlab but didn't know about this feature. I'll give it a try and tell you if it's working.

    The not-working zip file: I zipped it with the command line zip tool from MacOS X because the zip command in the Finder creates some subfolders which might be confusing for users from other operating systems. Maybe something went wrong. I can resend it if somebody needs it but I will try to do it in meshlab first.

    thank you,
  4. Martin_
    Martin_ New Member

    it worked very well.

    One thing should be mentioned. It is only possible to create positive offsets, which creates a wall to the outside. If I put in a negative offset then the resulting mesh is empty.

    I solved this by inverting the normals orientation and using a positive offset again -> thin wall to the inside

    best regards
  5. Martin_
    Martin_ New Member

    I confused something with the offsets. Actually there is no difference between inverted and non-inverted normals.

    Meshlab creates two offset surfaces. One to the inside and one to the outside. The outside one however can be deleted.

  6. stop4stuff
    stop4stuff Well-Known Member

  7. Martin_
    Martin_ New Member
    Oops again. I should have better read the whole message again before asking dumb questions :)
  8. dazhazit
    dazhazit New Member
    There's a freeware modelling tool called Blender. Since they've improved the UI it's a lot easier to use but there's still a learning curve.
    One of its' basic built in functions is to solidify a mesh (Menu options Mesh/Faces/Solidify). You can specify a thickness in the UI panel in the bottom left. Alternatively you can use an 'On The Fly' realtime modifier.
  9. Martin_
    Martin_ New Member
  10. christopherlowe
    christopherlowe New Member
    remember that if you intend to print mr. bunny that you leave a hole so that extra material can escape...

    little FYI
  11. Martin_
    Martin_ New Member
    Yes, thank you. I have a hole in the bottom. Should be big enough to put in an easter egg ;)
    Last edited: Apr 4, 2012