Hi guys, I have an exam and I should model this camera, but I stuck with the part that looks like an accordion can anyone have an idea that how can I draw that part?
@mehlikamerve didn’t specify whether his task is to produce a design model with nice crisp folds, or a photorealistic model with the sort of folds you get in leather. If the latter, then nurbs are not a good choice, but the new Subd features in R7 are much more amenable.
Guidelines (a scaled series of rectangles, with every second rectangle rotated 90 degrees)
can be overlaid with a Subd box, creased along the outside edges to give a sharp outline and scaled to fit the end rectangles before subdividing to give the same number of edges as folds. Thne pushing the vertices to the guide rectangle corners, followed by filleting the longitudinal edges and adding smaller fillets along the edges matching the rectangles. And then some more edges interspersed so the the straight lines can be tweaked into slight curves. Leading to something like this:
It needs quite a lot more tweaking, but the promise is there.
Regards
Jeremy
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Thanks a lot!
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How did you achieve the geometry? I’ve been trying to replicate it but I’m struggling
Hi Alexander,
Assuming you are following the outline I gave above, at what point are you struggling?
Regards
Jeremy
Hi Jeremy.
I’m fairly new at grasshopper and at times, certain parameter families like lists and domains confuse me still. Just the first guideline of making a series of scaling rectangle, this is the best I’ve gotten so far and I’m not sure why the first 10 are spaced differently.
Thanks,
Alex
Hi Alex,
I did the whole thing in Rhino, no Grasshopper used. If the issue is how to do it in Grasshopper, then I am going to ask @wim to split this thread and move your initial post onward into a new topic - and include a reference back to my original process description.
You’ll likely get more help from Grasshopper guru’s that way.
Something to consider: if you want to get that natural look you need to make a lot of subtle little adjustments to the folds to soften them, make them irregular and to introduce blemishes. I am not sure that it is cost-effective trying to do that in Grasshopper.
Regards
Jeremy
Hi Jeremy, when I saw the notices I wanted to answer even if it’s too late. You saved my CAD exam that time and I realized I didn’t give the proper thanks to you, soooo, thank you for that! Here is the final result of that camera modeling of mine, and thanks again! 
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Cool. Is it a reproduction of a specific camera or your own design?
It was a specific camera that my teacher assigned us for our exam
I was looking at the files posted above and something didn’t make sense to me so I folded some paper.
My definition uses Kangaroo to deform the shape of the bellows. The simulation works quite well but needs a reset after moving the anchors every now and then.
The input shape isn’t parameterized yet.
bellows.gh (68.8 KB)
When pushing the anchor downwards, the collision fails at some point. @DanielPiker I tried to add a no fold through goal but it didn’t work. Could you please take a look?
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Hi Martin,
This sort of mechanism is only possible through some stretching of the material, as I was mentioning recently here Origami folding - kangaroo constraints - #5 by DanielPiker
Not necessarily a problem, but it can complicate things a bit.
It looks like the mesh created in this definition has some issues with extremely short edges and self-intersecting faces, which would probably be part of why it won’t work with NoFoldThrough. Even after fixing that I didn’t get it to work well though. It looks like there’s some problem with the hinge and nofoldthrough goals on these long triangles.
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I found the mistakes in my mesh in the meantime too. Instead of the no fold through I tried to use the rod goal on an additional line connecting the outermost corners.
bellows.gh (52.1 KB)
Playing with a small bellows (for a 35mm SLR) what I see happening is that the leaves of the bellows are flat when compressed but take on an increasing curve perpendicular to the hinge edges as they are extended. There may be some stretch, particularly around the corners but this is not visible. The curvature is very much so.
I hope you are going to add a gravity goal for the larger cameras: https://photographylife.com/wp-content/uploads/2021/09/Chamonix-12x20-Ultra-Large-Format-ULF-Camera.jpg
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