Making inflatables..confused about unrolling surfaces


#1

Hi there, Im making inflatables so need to get the surface pattern off various forms. If I stick to geometric forms, I simply loft then unwrap the developable surface…its frustrating because I want to unwrap asseymetrical curved forms/surfaces.

Do I need to convert curves to polylines first I wonder…?

What is a developable surface anyway?

So if I make my simple curved form say a bean shape then how do I construct a developable surface over/around it that can be unwrapped?

Im only working on Rhino 2, is it worth upgrading to Rhino 5…am I missing out on some fab tool that will enable me to achieve my aim here.

Heres a picture of the form I just made. I was hoping to simply unwrap half of one side to get my pattern.(see highlighted surface area)
It is curved/has curved edges all round…Im now going to make it pointy and not use any curves and try again, however there must be a way to make curved shapes, perhaps simplify them so I can unwrap them??

starfruit2.3dm (110.5 KB)


(David Cockey) #2

The key to unrolling a surface is the surface needs to be developable or close to developable.

The most versatile way to create a developable surface in Rhino is DevSrf, a free plug-in. http://wiki.mcneel.com/labs/devsrf You will need Rhino 4 or Rhino 5.

Some reading on developable surfaces:
http://www.rhino3.de/design/modeling/developable/
http://www.boatdesign.net/articles/developable-surfaces/

A surface which is not developable can be flattened with some stretching or shrinking in Rhino 5 using the Squish command.


#3

Hi David, thanks so much for your help, I will upgrade to Rhino5 -my life could now get easier !!

Lisa:)