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Stratagizer
A Regular

USA
343 Posts

Posted - 01/30/2010 :  13:45:52  Show Profile  Reply with Quote
I have been asked to create a variation on Escher's mobius strip -but like a hamster wheel, as opposed to marching ants (see attached) So there should be 2 curved paths (extruded to form the outer frame) with straight wire crossbars. Using the elements of a traditional hamster wheel, but reformed as a mobius strip. It also has to form the "infinity" symbol when finished. Trying to create a geometrically perfect path with the correct twist is a challenge for me with the tools at hand. Any ideas?

I have made a VERY rough model of this as a test, but it is NOT a mobius strip (see image).

To add to the challenge, even though this will be a still image, it should appear to be in motion (as if the "hamster wheel" were spinning) I can probably fake that part in PShop, but perhaps a single frame render capturing the movement of the crossbars with a slow shutter speed + motion blur would create a realistic effect. I'm guessing I would need to have the motion bars move along an animation path that would be a duplicate mobius strip centered between the two that form the frame? I hope I'm being clear on this.

I have attached the MC Escher mobius and my first rough test.

Which wizard of the forum will be the first to solve the puzzle!

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jpro
A Fountain of Information

USA
4804 Posts

Posted - 01/30/2010 :  14:07:42  Show Profile  Visit jpro's Homepage  Reply with Quote
Do you have a budget to hire a forum wizard? This is probably more involved than I would be willing to take on as a freebie.

Jean
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silversurf
A Regular

Australia
225 Posts

Posted - 01/30/2010 :  22:00:43  Show Profile  Reply with Quote
Here's the 3D model:
http://www.turbosquid.com/FullPreview/Index.cfm/ID/364946

and some reference, scroll down to get to the Mobius part.
http://www.cs.technion.ac.il/~gershon/EscherForReal/

Good luck.
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Stratagizer
A Regular

USA
343 Posts

Posted - 01/30/2010 :  22:39:30  Show Profile  Reply with Quote
Thanks for the reference- budget and turnaround are tight, so I'll try refining the model, if that doesn't work, I'll just photoshop the whole thing. I just assumed someone here had done this before, and the simple -and obvious solution was hidden in plain sight. I'm pretty handy w/vector drawing, and I guess I'll use a combination of that + modeling. Thanks again!
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jpro
A Fountain of Information

USA
4804 Posts

Posted - 01/30/2010 :  23:00:32  Show Profile  Visit jpro's Homepage  Reply with Quote
I've seen tutorials for how to do a mobius strip. It actually shouldn't be too tough, but it would take a little fiddling.

The turbosquid model looks like a good start to me.

Jean
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Stratagizer
A Regular

USA
343 Posts

Posted - 01/31/2010 :  02:02:46  Show Profile  Reply with Quote
I looked at the turbosquid models & found this -fairly close to what I need in form (infinity symbol).

Yes Jean, sometimes there's no trick -just some "fiddling". The hard part will be creating perfectly symmetrical geometry.

http://www.turbosquid.com/3d-models/3ds-mobius-strip/396686
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jj
Inquisitive

United Kingdom
53 Posts

Posted - 01/31/2010 :  05:13:12  Show Profile  Visit jj's Homepage  Reply with Quote
Did something similar but not as complex a while back. No quick fix, just took a bit of time particularly getting the hamster wheel rungs in place.



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filip c
A Regular

Belgium
126 Posts

Posted - 02/01/2010 :  01:45:25  Show Profile  Visit filip c's Homepage  Reply with Quote
I would do this as follows:
- draw rectangle
- draw circle
- path extrude rectangle along circle
- covert to skin
- edit and move/rotate parts until you get the desired result
- convert to poly mesh
- ...

Edited by - filip c on 02/01/2010 01:52:03
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Stratagizer
A Regular

USA
343 Posts

Posted - 02/01/2010 :  13:47:16  Show Profile  Reply with Quote
Thanks Silversurf - I did purchase the Turbosquid model -its a PERFECT Mobius Strip. But is a "strip" one version of which is extruded, the other a series of single connected faces. I tried deleting the connecting faces, hoping that I could convert the remaining edges to bezier. My plan was to then extrude a disc along the bezier & create a perfect frame for the "hamster wheel". But I was not able to convert the edges to bezier. In fact, once I exited poly edit mode, I was not able to do anything with the remaining edges -I was not able to even select them if I re-entered poly edit mode. There was only an empty bounding box. (See screenshots) Is there a way to convert the outer edges to a bezier that would accept a path extrusion in Strata? This would theoretically yield a perfect frame to which I could affix crossbars.

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jpro
A Fountain of Information

USA
4804 Posts

Posted - 02/01/2010 :  14:01:26  Show Profile  Visit jpro's Homepage  Reply with Quote
Chris has a technique for converting edges to bezier curves, but it is pretty convoluted. He posted it here recently, though, in one of the spiral threads.

I prefer this technique, which is simpler, and should work just fine for the geometry you have.

http://www.stratacafe.com/image.asp?imageID=23003&artistimages=1&killnext=0

Jean

Edited by - jpro on 02/01/2010 14:02:09
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Stratagizer
A Regular

USA
343 Posts

Posted - 02/01/2010 :  14:39:32  Show Profile  Reply with Quote
Thanks Jean -I'll check that out. I was able to manipulate the model to get a fairly decent frame (a LOT of stitching & filling!) If I can smooth this out a bit more, then add the cross bars (perhaps with bridging) I think I can pull this off. But the sections are elongated, which makes for some funky smoothing -even when subdivided. Will possible have to extrude each rib face for more detail(!)

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jpro
A Fountain of Information

USA
4804 Posts

Posted - 02/01/2010 :  14:52:45  Show Profile  Visit jpro's Homepage  Reply with Quote
You shouldn't be getting that funky smoothing because of long segments: the one does not follow the other. I suspect you have internal faces at each segment. That would cause the dip at each section.

Jean
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Stratagizer
A Regular

USA
343 Posts

Posted - 02/01/2010 :  15:23:08  Show Profile  Reply with Quote
Right you are (as usual Jean) I thought that was the case earlier, but "dissolve" deleted the entire model, I just used "delete" -which worked (duh!), and now all is good! Thanks. Now I just have to stitch together the crossbars.
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