Minimal Surfaces

Replies to This Discussion

Permalink Reply by Danny Boyes on September 28, 2009 at 7:15am

Hi Sean,

These two scripts where from David's Reconstructivism website which no longer exists. They let you use Rhino to create minimal surfaces. I've used them to create simple canopies and awnings, never anything more complex, but they should be right up there for your needs.

Attachments:

• NurbsRelaxation.rvb, 43 KB
• MeshRelaxation.rvb, 29 KB

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Permalink Reply by Joey Sarafian on January 18, 2011 at 6:19pm

Is it possible to use these scripts to drape a surface over a chord for example?

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Permalink Reply by John Hsu on April 29, 2011 at 10:44pm

Hey, Danny

 

I understand what you mean here, but when I try it myself, it's not working. The script is good, but when i use the rhino sample, it says the surface was trimmed, and I have to rebuild the surface again. However, no matter how i do, the red surfaces are not gonna do anything.that is what it happens to me, did I miss sth.? What I wanna do is to connect the 3 red colour surface instead of the big one.

 

Can u help me with this?

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Permalink Reply by Torolf Sauermann on September 28, 2009 at 8:15am

Hey Sean,

I will reconstruct the object times the evolver and the result of post here :)

ciao
torolf

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Permalink Reply by Sean on September 28, 2009 at 8:27am

Thanks for the scripts Danny, i better learn how to use them now, never used scripts in rhino before.

Sorry Torolf, but what is the evolver? i'm slightly confused, perhaps your next post will clear things up :).

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Permalink Reply by Torolf Sauermann on September 28, 2009 at 8:38am

ups...sorry ;) surfaces evolver http://www.susqu.edu/brakke/evolver/evolver.html

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Permalink Reply by Sean on September 28, 2009 at 8:58am

Ahh i see. I had downloaded this program a few days ago, but haven't used it yet.

I'm just skimming through the manual now myself, so perhaps i may find out however,

Do you know if surface evolver could find the minimal surface between 3 or more circlular frames, like the above image?

Thanks,
Sean

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Permalink Reply by Andrew Heumann on September 28, 2009 at 6:59pm

Also take a look at RhinoMembrane - http://www.ixcube.com/dettagli.asp?n=20. It takes a mesh, some constraints (edges, points, whatever) and relaxes it into a minimal surface. Really fun and relatively easy to use. There is a demo available for download that will let you get a feel for the software.

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Permalink Reply by Jon Mirtschin on September 29, 2009 at 1:45am

I've a minimal surface solver in my structural tools plug-in. Trouble is it has a very primitive user interface and strict requirements for understanding how to use it, and I don't have time to develop it at this moment.

However, without making any promises about how good a result I might be able to achieve, I'd happily try and apply it to your form if you prepared a rhino model of it. The most important details needed from the model are the constrained edges (ie the circles that are fixed). If you could either create a basic cylinder from top to bottom (or do a basic loft from those circles) and then boolean union to some lateral cylinders (or loft surfaces) so that you have the basic arrangement of form, I'll try to see if the solver can relax it into the minimal surface. Not that it will produce a "mesh" or polysurface form of the minimal surface, one of the reasons I hadn't pursued this with priority is that I have figured how to get a NURBS result. Possibly T-splines plug-in or something might be able to help out with this part.

Cheers,

Jon

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Permalink Reply by Sean on September 29, 2009 at 2:16am

Thanks for your reply Jon.

I'll get onto making a rhino model right away, as time is ticking away, and the assignment is due in about a week. Luckily it is a research assignment, so while i do need an end product, the research and process that goes into generating a form is equally (if not more) important.

What type of surface does your surface evolver produce (sorry i was a little confused). I'll try and get something done up in rhino tonight. The surface i have will be quite a bit simpler than the above project, though it does still use 3 circle frames, with the minimal surface spanning between them.

I do have T splines, although my free trial runs out in a matter of days (cons of being a student) :(

Thanks in advance for your help,

Sean

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Permalink Reply by Jon Mirtschin on September 29, 2009 at 5:36am

Hi Sean,

I've had a look at this, and refernce two progress models that will give you an idea of the input model and the type of result we'll end up with. There's an underlying cylinder surface, that i have split some holes in. I have meshed the surfaces in Rhino, and then displaced the void edges and run the surface relaxation on that. The closer you can get the starting surface to the intended profile, and the better the mesh we can generate for it (something I'll look at it), the better the result we will get. Also the smaller the mesh element the better the result. Both of these are progress, that I terminated before completion of the calculation. You can see from the first example that necking became apparent. I'm not an expert in minimal surfaces, but it might be a fine line between finding nice shapes and not having necking occur. The second example I had the different voids closer to each other so they influenced each other. The result is starting to become more akin to the intended outline. This mightn't be useful for you, but at least is an insight into one approach of determing these types of shapes. This approach suits flexible, user defined boundary conditions. There are some mathematical solutions to determine nurbs surfaces for particular minimum surfaces. Refer http://www.rhino3.de/album/math/index.shtml

I've uploaded the file to my wiki, as the file size is too big for the grasshopper ning. http://ssi.wikidot.com/local--files/downloads/cylinder%202.zip

Cheers,

Jon

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Permalink Reply by Sean on September 29, 2009 at 11:44am

Hey Jon thanks for the reply, i'm quite excited. I had initially thought incorporating minimal surfaces into my assignment wouldnt be possible, but perhaps i can still manage it.

Do you know if this model would still work if the top and bottom of the cylinder wern't open, but capped? In this case only the openings around the cylinder would create the interor shape.

I'll post a quick example file here, its in nurbs not mesh, but hopefully it will get across my intent.

Hope this isn't pushing my luck too far, but if it is possible, it would be amazing. :)

Thanks,

Seam

Attachments:

• test1.3dm, 109 KB

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