Creating A Pattern For A Sphere In Rhino

[sgoti]

So…

I've downloaded/installed my 90-day evaluation copy of Rhino 5 for the Mac. (Playing around to see if I really want to purchase it, MIGHT be able to qualify for the student discount through my apprenticeship. PLEASE OH PLEASE!)

Anyway, I've started playing around a bit, and naturally have tried to do what apparently is a non-trivial task: Make a sphere, and then create a 2D pattern that will build up into same.

Looking for something like the attached picture (Which, BTW, is from the page explaining what UnrollSrf can/cannot do).

So far, I've learned that the UnrollSrf command will not work, due to the sphere's surface curving in more than one direction.

Various Google searches have pointed me towards the "Squish" command, but results have been… Not what I expected/am looking to achieve. More of a bug splat, actually…

I'm beginning to understand developable and non-developable surfaces, but that's as far as I've gone.

Can anyone help (or at least point me in the direction of a good tutorial on this)?

Thanks!

[ser400]

you will notice that it is not round, it is flat sections that form the non-circular sphere. That is how they are able to unroll the develop-able surface. You simply cannot unroll a surface that curves in two directions, as you have found out. In paper model design you have to compromise somewhere so your surface needs to be flat or planar in at least one direction. You see this with all paper models, where you choose to make the compromise is the "artistic" element that makes the model look more realistic or not.

I hope this helps.

Bruno

[sgoti]

Originally Posted by ser400

you will notice that it is not round, it is flat sections that form the non-circular sphere. That is how they are able to unroll the develop-able surface. You simply cannot unroll a surface that curves in two directions, as you have found out. In paper model design you have to compromise somewhere so your surface needs to be flat or planar in at least one direction. You see this with all paper models, where you choose to make the compromise is the "artistic" element that makes the model look more realistic or not.

I hope this helps.

Bruno

Understood…

So how do I get something that approximates a sphere (or any compound curve)? People are creating paper models with (pseudo-)compound curves in Rhino somehow…

I may have (partially) found the answer:

1) Create mesh from surface.
2) Unweld with angle of "0". (Thank you, Google!)
3) Explode the mesh.

So… I now have a collections of trapezoids and triangles approximating a sphere. (More polygons = smoother sphere).

Now what?

I am assuming I need to join/weld/whatever shapes to create each piece…

Will keep looking and experimenting.

[goodduck]

1: Select "Edit" > "Rebuild".

2:Rebuild window may look something like this.

3: For this I will set keep Point count "U" at 10 and set the "V" at 5. And I'll set the Degree "V" at 1.

4: Sphere rebuilt and now can be unfold.

5: Select "Surface" > "Unroll Surface".

6: Select "Explode=No" or "Explode=Yes".

7: Sphere unfolded.

[sgoti]

Originally Posted by goodduck

1: Select "Edit" > "Rebuild".

2:Rebuild window may look something like this.

3: For this I will set keep Point count "U" at 10 and set the "V" at 5. And I'll set the Degree "V" at 1.

4: Sphere rebuilt and now can be unfold.

5: Select "Surface" > "Unroll Surface".

6: Select "Explode=No" or "Explode=Yes".

7: Sphere unfolded.

SUH-WHEET!

Thanks, Alan. This is exactly what I was looking/hoping for!

[sgoti]

Hee hee!

Unfolded a pattern where each section was only 3.6 degrees wide…

Yes, 100 sections for a complete sphere. No, I am NOT going to try and assemble it!

Thanks again, Allen and everyone else for your help!

(And Allen, sorry I misspelled your name last time…)