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Create thin walled model of the Stanford Bunny [message #46278] Sun, 01 April 2012 07:20 UTC Go to next message
avatar Martin_  is currently offline Martin_
Messages: 7
Registered: March 2012
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Hi,

I need to print out the Stanford Bunny
http://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

[Updated on: Tue, 03 April 2012 10:05 UTC]

Re: Create thin walled model of the Stanford Bunny [message #46279 is a reply to message #46278 ] Sun, 01 April 2012 08:37 UTC Go to previous messageGo to next message
avatar stop4stuff  is currently offline stop4stuff
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Registered: June 2010
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Hi Martin,

Welcome to Shapeways! Smile

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

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
Re: Create thin walled model of the Stanford Bunny [message #46280 is a reply to message #46278 ] Sun, 01 April 2012 09:09 UTC Go to previous messageGo to next message
avatar Martin_  is currently offline Martin_
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Registered: March 2012
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Hi Paul,

thank you very much for your quick answer. I found the post from dizingof you mentioned
http://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
Re: Create thin walled model of the Stanford Bunny [message #46281 is a reply to message #46278 ] Sun, 01 April 2012 10:23 UTC Go to previous messageGo to next message
avatar Martin_  is currently offline Martin_
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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
Re: Create thin walled model of the Stanford Bunny [message #46283 is a reply to message #46278 ] Sun, 01 April 2012 12:14 UTC Go to previous messageGo to next message
avatar Martin_  is currently offline Martin_
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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.

Re: Create thin walled model of the Stanford Bunny [message #46284 is a reply to message #46283 ] Sun, 01 April 2012 12:27 UTC Go to previous messageGo to next message
avatar stop4stuff  is currently offline stop4stuff
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stop4stuff wrote on Sun, 01 April 2012 08:37


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.


Cool

Wink
Re: Create thin walled model of the Stanford Bunny [message #46286 is a reply to message #46284 ] Sun, 01 April 2012 12:56 UTC Go to previous messageGo to next message
avatar Martin_  is currently offline Martin_
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Oops again. I should have better read the whole message again before asking dumb questions Smile
Re: Create thin walled model of the Stanford Bunny [message #46313 is a reply to message #46278 ] Mon, 02 April 2012 12:04 UTC Go to previous messageGo to next message
avatar dazhazit  is currently offline dazhazit
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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.
Re: Create thin walled model of the Stanford Bunny [message #46365 is a reply to message #46278 ] Tue, 03 April 2012 10:12 UTC Go to previous messageGo to next message
avatar Martin_  is currently offline Martin_
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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

Re: Create thin walled model of the Stanford Bunny [message #46425 is a reply to message #46365 ] Wed, 04 April 2012 01:26 UTC Go to previous messageGo to next message
avatar christopherlowe  is currently offline christopherlowe
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remember that if you intend to print mr. bunny that you leave a hole so that extra material can escape...

little FYI


please visit my blog at...
http://chrisshopofmodels.blogspot.com
Re: Create thin walled model of the Stanford Bunny [message #46432 is a reply to message #46278 ] Wed, 04 April 2012 06:19 UTC Go to previous message
avatar Martin_  is currently offline Martin_
Messages: 7
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Yes, thank you. I have a hole in the bottom. Should be big enough to put in an easter egg Wink

[Updated on: Wed, 04 April 2012 17:36 UTC]


 
   
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