This image shows the mesh version but I have created a poly surface from the mesh as well that looks the same just with some isocurves thrown in. I don’t know a lot about editing meshes so I am a bit lost when trying to tweak the mesh.
I’ve tried a number of things with the polysurface and I thought I had an easy way to do it by exploding it into surfaces and using the merge surfaces command. But because I am dealing with triangles here there is always one edge of the surface that is trimmed and therefore won’t merge.
Is there a somewhat simple way to go about this? I guess i could Extract the face borders, offset every single triangle in a bit and then do some sort of blend but there are a ton of triangles and they all have different normals and they aren’t all the same size so that would take me forever.
I am doing this for rendering purposes and not fabrication if that makes a difference.
Hello - in this case, if you do not need a mesh, it might be simplest to draw a 90 degree arc and Revolve it or split a Sphere in half… i.e. make the simplest surface you can.
I probably should have added a few more details about the model. This is one of those geo domes that has a steel skeleton and a fabric stretched over it. Something like this:
It’s a thick fabric or membrane that is stretched over the steel underneath so the edges of each triangle are bumped out slightly with a smooth round over effect while the interior of the triangle is relatively flat. I’ve got all of the steel and interior modeled it is just getting the exterior to look right for renderings that has me stumped. I actually attempted this stretched effect years ago in rhino and came up short.
Doesn’t matter whether it is a mesh or not. Weld doesn’t quite do it. The closest so far was merging two surfaces but because I am dealing with triangles it’s a dead end. The client needs nice renderings for promotional and sponsorship purposes so I want to get it right. Most of all, I just want to conquer this on a personal level. I battled this 7 or 8 years ago and need some redemption
Thanks for chiming in. If you have any more thoughts throw them at me and I’ll give them a try.
If you look at the triangles closely, the canvas is not stretched 100% taut across the space frame. This dome has a high level of symmetry. You could just model the primary domain with triangles that give the impression of being ever so slightly depressed, fillet between them, and then just copy/rotate to complete the model. This way you have most control over the formal aesthetic expression.
Another approach, much faster, would be to UV unwrap your existing model and simply paint a displacement map for your renderer. That way, you could very easily introduce variations regarding the feeling of tautness or depression, so the rendering in the end does not look to uniform and unrealistic.
Building on this - if you model just one triangle as a surface/polysurface, you could quickly map it to all the faces of your dome using the “Triangle Mapping” component in Grasshopper
One of the first things I tried. Can’t get a radius that is large enough to be noticed from anywhere but very close up. I also need to be able to export this to another software that doesn’t support anything like edge softening.
There are a lot of variations of these domes depending on what they will be used for. The one I am working on has an interior dome ceiling suspended from the metal struts that is perfectly smooth. The smooth dome is created by creating a vacuum in the space between the outer cover and the inner dome ceiling. So, yes it is not 100% taut but it is still tighter than the example photo I provided.
You are correct about the symmetry. I think it has five repeating identical groups of triangles that go from the very top to the very bottom.I had kind of forgotten that so thanks for reminding me.
I am thinking that grasshopper might be the way to go and maybe in conjunction with weaverbird. I rarely use rhino for work purposes so I have never gotten around to learning grasshopper. I just started watching and reading grasshopper tutorials last night as a matter of fact. Hopefully in a day or two I can enough of a basic understanding to come up with some solution using grasshopper.
There are 8 or 9 different ones. When I started this I figured that they would all be the same size.
I’ve got some ideas that came to me that I will try out today or tomorrow sometime and will post my results.
But keep the ideas coming if you have one. You guys know more than I do. Thanks
The triangle mapping component will distort your input surface to match the 3 corners to all the different shapes of triangle you have in your dome. trianglemap.gh (9.6 KB)
@DanielPiker method is a more sophisticated way to build the dome. Weaverbird, or similar alternative, is a more simplistic ‘brute force’ method to manipulate your existing dome for a more realistic render. Both in concert might be effective too.
These kinds of projects are good impetus to learn Grasshopper. Stick with it, and you should reap rewards that will pay dividends in future.
Grasshopper is going to be the way to go. I can’t believe I have put off learning it this long but sometimes it is hard for me to force myself to sit and watch tutorials.
Most software I can just start to play around with and get the basics of quickly. But I’m totally lost when I start grasshopper. If you all know of a particularly good set of tutorials or some other resource for grasshopper let me know.
