How Would I Model This Minimum Surface?

Hey All,

This is my first post, as I am still learning Rhino / Grasshopper. So please be patient haha! :P I am trying to model a particular form (see image below). I know the easiest way would be a script or some type of plug in. I’ve done searches on scripts and programs, etc. but I have come up unsuccessful.

I’ve gone through these threads religiously and still haven’t come up with a solution:

http://www.grasshopper3d.com/forum/topics/minimal-surfaces-and-tensile
http://grasshopper3d.ning.com/forum/topics/minimal-surfaces

I tried installing a demo of Rhino Membrane but it seems as it runs on only the current up to date version of Rhino.

Any help would be much appreciated!

Thank you,

Pietro Amoroso

Tags: fabric, minimum, rhino, structure, surface, tensile

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Permalink Reply by Jon Mirtschin on October 11, 2009 at 1:42pm

Hi Pietro,

I'm developing plug-ins relating to structure, currently in beta testing in quite a few well known design offices.
I helped Sean with progressing some minimum surface finding for his assignment in one of the threads you mentioned above.

Is a mesh solution acceptable for your search? You're more than welcome to try solving your shape with my plug-ins, but beware I'm still developing and improving the tools, particularly with regards to manipulating Rhino meshes to determine a nice solution. I do already have some smoothing and vertex repelling routines that will help, however I am also working on a mesh resizing routine (which works, but struggles to process medium size mesh as would define your target surface). I've attached a first attempt at solving your problem. I'm happy to help you with the processes/methods needed to define this. If you already have access to a mesher (such as a FEA program), you can actually form find these quite quickly now using the tools.

But I am hoping soon to have a Rhino contained means of solving this from a Rhino generated mesh for the starting surface. The reason this first attempt looks flat at the base, is because the original Rhino mesh only added single elements between the base circles (which is why I need to implement an efficient mesh resizer quickly). The rhino mesh is not geneated with a "analysis" priority nature, which is why I'm creating tools to manipulate/modify it so that it is.

Get in touch if you wish to try this further. I'm shortly posting some tutorials for quite basic minimal surface finding on my blog.

Cheers,

Jon

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Permalink Reply by Pietro Amoroso on October 11, 2009 at 2:59pm

Thanks Jon!

Wow this is very impressive I may say! Your skills are way beyond my capabilities. I am a 6th year Architectural Grad Student at Arizona State and I am designing this form to create a fabric reinforced concrete that is about 1/2" thick. I just picked up on Rhino at the begining of the semester so I am fairly still new at it. I come from a 3D background (3DSmax, FormZ, Sketch UP, Revit, etc.), coming from an undergraduate architectural degree, but you can compare me to a novice to your skills lol!

I dont mind working in mesh. The plug-in I was working in before is mesh based as well. I would love to play around with your plug-in if its fairly easy to use. I am by any means at buff at this so this all sounds intimidating to me, but I am willing to learn and figure out this solution. I don't have access to a mesher unfortunately, but if I can get the bottoms to pop down, that would be it.

Thank you again,

Pietro

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Permalink Reply by Jon Mirtschin on October 11, 2009 at 3:09pm

The whole intent of the tools I'm trying to create is to equip all sorts of designers (not necessarily with strong technical background) with the ability to run these types of assessments. We made leaps and bounds during Sean's studies with running the plug-in solver on any mesh in Rhino (rather than requiring creating the mesh molder in an external finite element solver). I'm quite close with the mesh manipulator to resize (and internally split mesh elements), so if you're urgency for this allows us a few more days, I think it's worth waiting. If not, let me know and I'll try to outline the steps as it currently stands for playing around with this. As I said, walking through some slightly simpler examples will help. If I get a chance at work tomorrow, I'll mesh my current surface in Lusas and post a image/file of the plug-in solver with your desired profile. Then hopefully soon after we'll have a rhino contained calculation.

Cheers,

Jon

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Permalink Reply by Pietro Amoroso on October 11, 2009 at 4:09pm

With my frustration with the other plug-in at the moment I am willing to wait it out a few more days. :) Been trying to get this form for 3-4 days now.

I really appreciate this. I am going to see if I can play with some other methods in the meanwhile.

Thanks a lot Jon!

Pietro

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Permalink Reply by Jon Mirtschin on October 14, 2009 at 10:33am

Ok Peitro,
I've got my mesh translator up and running and at speed (at last, it was a bit of an effort). You can download the Structural Drawing Plug-in from http://ssi.wikidot.com/downloads . I don't have any time now this evening to do a blog tutorial, and you'll need a trial license to do this (so it will probably have to start running tomorrow).

To start, you need to mesh a joined polysurface using the Rhino command mesh.
Then run the weld command on the mesh (using a weld angle of 181 or greater) to join all coincident vertex. I think you also need to run the triangulate mesh command (though this won't be necessary next version).

There's three plug-in commands you'll use to get your minimum surface, sdrMinShapeMesh to solve for the mimimum surface (make sure you click the option to monitor progress so you can stop it if mesh elements start to neck out).
sdrMeshResize will resize a selected mesh, which is useful if you see the mesh necking (or stretching) into unequal proportion.
sdrMeshRepelVerts will repel the vertex away from each other to give a more even edge lengths which will give better answers.

I've attached my progressed file with some sample mesh. Note that it seems my circle radius is too large in proportion to the spacing. I'll try to reduce it tomorrow to get a shape more like your desired outcome. Also by running with smaller mesh size, it will produce better answers (but take longer).

I'm sure you'll need better instructions and more help, but hope this gets you thinking about it.
Cheers,

Jon

Attachments:

minimal surface.3dm, 1.4 MB

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Permalink Reply by Pietro Amoroso on October 14, 2009 at 5:07pm

Hi Jon,

Thank you for your help. Again, I really appreciate it. I’ve been playing in Rhino and discovered a way to accomplish the form I’ve been looking for. Someone suggest I use a plane, bump up the UV, with 3 degrees (for curvature), and pull on 4 control points on the plane. This gets the look of that form, however I am still interested in the plug in and the possibilities of it. There is no urgency so when you have free time I would love to learn this plug in. Maybe a brief tutorial would be nice to see how the final form you come up with was created.

Thank you again,

Pietro Amoroso

Here is the form I achieved:

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Permalink Reply by Roland Wiebicke on January 16, 2011 at 4:18am

I have a quite similar problem...

I have this triangulated mesh (that is supposed to resemble a building) and want the edge lengths to be about the same.

So I got the GeometryGym toolbar (thanx again for the license, Jon!)

Using the command sdrMeshResize with an target edge lenght of 1.8 meters/units i get this unsatisfying result:

I am quite new to rhino. I created the mesh from a lofted surface, hence the hole in the top. Should I try another way of modeling the building, or am I using wrong params? The building is supposed to look kinda like THIS...

btw: I seem to have problems with the sdrMeshRepelVerts command. I get this error message:

Sorry to bother...

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Permalink Reply by Jon Mirtschin on January 16, 2011 at 4:54am

That's a very unsatisfying result. Any chance you can email me the associated files so I can take a look and try to improve?

I couldn't get the mesh repel verts command to give that error on my test cases, so it would be great if I can see your model.

I have other routines not in SDR, developed for canopy roofs or similar I've helped on, to create a panelling of equilateral triangles (within tolerance). If I get the chance I'll try to apply it to your form.

Cheers,

Jon

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Permalink Reply by Roland Wiebicke on January 20, 2011 at 11:27am

I helped myself out with an approximation now. I created a dome with triangle surfaces, using a gh-script I downloaded from somewhere around here (geodesic.ghx). Caged the hole thing with a circle of the same size and deformed it...Not the real thing, but I'm in a bit of a hurry, the final presentation is coming up in two weeks...

So far, so good. But how could I get this hole thing meshed now? I´d still like to have triangular meshes from this exact grid...

I sense I have to do something with "Delaunay Mesh" and "Proximity 3D" from the Triangulation Toolbar. Tried, but no success so far...

Thx,

Roland

Permalink Reply by Daniel Piker on January 16, 2011 at 5:04am

Have you tried using surface distribution in Kangaroo ?

Post the file and I'll have a look too.

See these discussions for some more info:

http://www.grasshopper3d.com/forum/topics/triangulation-scrip-with?...

https://groups.google.com/group/kangaroophysics/browse_thread/threa...

There's also some more powerful new mesh optimization tools on the way :)

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Permalink Reply by Hirsa Azizi on March 4, 2012 at 7:46pm

Hi Pietro, I am having very close issue as you had. the image you showed is what I am trying to get in rhino model. did you find any solution can you help me please?

Thanks

Hirsa