A 70's revival: the Utah Teapot

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A 70's revival: the Utah Teapot

Ronaldo
Some young people may be enchanted by the music, fashion and ideas of the 70's. Few of them, however, have heard about the Newell's teapot, a hit in the Computer Graphics community. Created in 1975 by a researcher of the University of Utah - Martin Newell - , the teapot model was a star of many bench tests of new realistic graphic algorithms and techniques. You will find a historical appraisal of its pedigree in an entry of Wikipedia: "Utah Teapot".

The Utah teapot dataset spread around the world beyond the following decade and may be found yet here and then. It contains the control points of 28 degree 3 Bezier patches that defines the outer surface of the main teapot body, its lid, its spout and its handle. It is not a solid however. It misses the interior surfaces of the main body and the spout, has no bottom closure, and the handle doesn't meet the body nicely.

I have been working in a modelling system that allows the use of Bezier surfaces as boundary of OpenSCAD models. It is now under tests and I thought that the Utah Teapot would be a nice demo of the system. I have completed the teapot model correcting some imperfections in the handle and creating a internal surface where it is needed. And I got this outcome.

This is a render of the model and it has passed all CGAL checks so it can be boolean-operated with other solids. Here is a difference operation that shows the internal surfaces of the model:

How this model was built? Well, it is the boolean operation of 3 polyhedron (the spout, the handle and a solid to make the spout hole in the main body) and two rotate_extrude of Bezier curves (the main body and the lid). I could avoid the use of rotate_extrude but I have prefered that way to illustrate many modelling alternatives. To model the main body, I extracted the control points of a profile (section) of the main body from the dataset, and used that to feed rotate_extrude. The lid has been made the same way. For the spout and the handle, I have used the dataset patches, added patches for the  spout inner surface and close their ends with planar faces.

For each independent part (spout and handle), I collect all the surface information (vertices of planar faces and meshes of Bezier surfaces) and send all to a module which builds the data for a polyhedron primitive. That module scan the data, builds the vertex lists and the triangular face lists without caring to identify the common vertices of adjacent patches or adjacent to a face and a patch. So the vertex list sent to the polyhedron has many repetitions. CGAL cares to consolidate the vertex list and builds a solid when the union of all surfaces is a manyfold.

My lifemate was kind to 3D print the teapot from a stl file I generated with OpenSCAD. A very tiny teapot: with a diameter of only 1 inch.



I was amazingly surprised that a so small version of the teapot is able to pour water from the spout!


Pourring water-1024.jpg
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Re: A 70's revival: the Utah Teapot

Neon22
Really nice to see a physical instantiation of the Utah teapot. Thanks.
Looking fwd to seeing whatever it is you're doing :)
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Re: A 70's revival: the Utah Teapot

Michele
In reply to this post by Ronaldo
On 04-22-2016 7:48 PM, Ronaldo wrote:
> Some young people may be enchanted by the music, fashion and ideas of the
> 70's. Few of them, however, have heard about the Newell's teapot, a hit in
> the Computer Graphics community.
>    

Yes indeed.  The Teapot was all the rage at SIGGRAPH for a while in the
80's.  IIRC, it made the cover of the Proceedings one year.  Thanks for
the trip down memory lane.  I'll have to print this one out for sure.

             - Michele



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Re: A 70's revival: the Utah Teapot

Kenneth Sloan
There’s a decent .stl file floating around (thingiverse?)  I downloaded it and printed a full-size model a few years ago.

I don’t think I want tea brewed in an ABS pot, but it appears functional.

Which, of course, means that the .stl model is wrong.  The original model didn’t have a bottom.   And then there’s the whole “aspect ratio” thing…

Google is your friend.  If you can’t find Google, find an old guy who was there in the beginning.  I’m a newbie.  I didn’t make it to the first SIGGRAPH.  My first one was 1976, I think…

--
Kenneth Sloan
[hidden email]
Vision is the art of seeing what is invisible to others.




> On Apr 23, 2016, at 19:17 , Michele Denber <[hidden email]> wrote:
>
> On 04-22-2016 7:48 PM, Ronaldo wrote:
>> Some young people may be enchanted by the music, fashion and ideas of the
>> 70's. Few of them, however, have heard about the Newell's teapot, a hit in
>> the Computer Graphics community.
>>  
>
> Yes indeed.  The Teapot was all the rage at SIGGRAPH for a while in the 80's.  IIRC, it made the cover of the Proceedings one year.  Thanks for the trip down memory lane.  I'll have to print this one out for sure.
>
>            - Michele
>
>
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


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Re: A 70's revival: the Utah Teapot

Ronaldo
In reply to this post by Michele
Michele wrote
 I'll have to print this one out for sure.
Well, you will need a stl file for that:
teapot_demo.stl

As I remarked and Sloan confirmed, the original Newell's teapot is a rather incomplete model. Here you may have an idea of the original model:

I will publish my Bezier libraries and modelling system as soon as it has been enough tested. By now, for give you a glimpse of how it is used, you may take a look into the OpenSCAd file I used to render the teapot. It is a rather complete and complex demo though.

teapot_demo.scad
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Re: A 70's revival: the Utah Teapot

Michele
On 04-24-2016 11:01 AM, Ronaldo wrote:
Well, you will need a stl file for that:
teapot_demo.stl <http://forum.openscad.org/file/n17183/teapot_demo.stl>  
  
Thanks, and for the source code too!  That worked out very nicely without even needing support.  1987 was a big year for the Teapot at SIGGRAPH.  It was featured in no fewer than three papers.




            - Michele


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