Create thin walled model of the Stanford Bunny

Hi,

I need to print out the Stanford Bunny
https://graphics.stanford.edu/data/3Dscanrep/

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
Martin

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

Paul

Hi Paul,

thank you very much for your quick answer. I found the post from dizingof you mentioned
https://www.shapeways.com/forum/index.php?t=msg&goto=4119 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,
Martin

Hi,

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
Martin

Oops...

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.

Oops again. I should have better read the whole message again before asking dumb questions

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.

Thanks to everyone. I made two versions with about 1.2mm and 2mm wall thickness and uploaded them to shapeways. I didn't make it public because I don't know about the licensing issues for the model. If anybody needs it please get in touch with me and the creators of the model.
http://graphics.stanford.edu/data/3Dscanrep/
http://www.cc.gatech.edu/~turk/bunny/bunny.html

Martin

remember that if you intend to print mr. bunny that you leave a hole so that extra material can escape...

little FYI

Yes, thank you. I have a hole in the bottom. Should be big enough to put in an easter egg