Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Breaking a surface of a Sphere in to Triangles? 1

Status
Not open for further replies.
penguin221

penguin221

Industrial
Joined
Sep 11, 2003
Messages
30
Location
US
Does anyone know how I can take the surface of a sphere and make it into triangles? An example would be the Spaceship Earth Globe at Disney's EPCOT.



Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Sort by date Sort by votes
You can export it into STL format, but the triangle orientation won't necessarily be predictable. Adjust the resolution settings to get what you want.

(Not sure if you can bring it back in to SW without another program to convert to parasolid or IGES.)




Jeff Mowry
Industrial Designhaus, LLC
 
Upvote 0 Downvote
If you want uniform triangles, you will need to do it manually. Perhaps use a 3D sketch to place points on he sphere and then connect with lines.

Exporting as an STL will break the surface into triangular facets, though you won't have much control over the shape of the facets.

One possibility is to use an FEA mesher, perhaps from COSMOSWorks. You could at least get node positions and triangular elements. I'm not sure how to translate a mesh back into geometry, though.

[bat]Due to illness, the part of The Tick will be played by... The Tick.[bat]
 
Upvote 0 Downvote
I want to be able to create geometry from the trangular surfaces.

STL will not work for this application.

Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Upvote 0 Downvote
One more thought:

Don't try to do the whole sphere. Do a sector of the sphere, perhaps 10°-15° of longitude in width. Also, perhaps separate that sector so that you can mesh the triangular tip separately, as well as other "rectangular" sectins in the middle.

[bat]Due to illness, the part of The Tick will be played by... The Tick.[bat]
 
Upvote 0 Downvote
Make a single or a double triangular section, and use a circular pattern and other types of patterns to continue the Spherical shape. I hope you follow what I'm after.

Regards,

Scott Baugh, CSWP [borg2]
CSWP.jpg

faq731-376
 
Upvote 0 Downvote
I don't know if this will work for you. I did something similar once. I created the sphere and did triangle extrude cuts, with the last sketch showing as reference for the next cut. Each triangle piece was saved as a separate named part. Then all parts brought together as an assy.
 
Upvote 0 Downvote
Well I guess that might work for a few triangles, but I need to breack the sphere into 11,520 equal triangles.

Don't think I want to create 11,520 cuts or assemble 11,520 parts.

Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Upvote 0 Downvote
penguin221,

If these triangular elements are the same then you'd need only one part. Make a subassembly with an appropriate pattern of these elements. This doesn't have to create the whole "sphere" in one fell swoop. You can then make an assembly of this subassembly. It might go a lot faster than you think, especially if you locate the part and the subassemblies using patterns instead of mates.

- - -Dennyd
 
Upvote 0 Downvote
I gotcha ya.

Now how the heck do you pattern a feature or part that is a triangle and get a sphere or part of a sphere?

I guess that is my dilema. I can't get trianlges to pattern well because there really is no symmetry to the final product. All the edges of the triangles create odd angles. I don't believe you can create a section of the sphere either, you will have to do it all at once.

I guess I am just lost and need to work at it some more.




Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Upvote 0 Downvote
It's a tough one. Ask a civil engineer or an architect. They may have an idea.
 
Upvote 0 Downvote
If its a geodesic sphere, you would have at least two sizes of triangles. Both their bases would be the same length but there would be two different heights. The shorter ones would make a hexagon with all vertices on the sphere. The taller ones would make pentagons with all vertices on the sphere. Take a look at a soccer ball and imagine dividing up the hex's and pent's into triangles.
There were a few examples of this in an issue of solid digital digest, maybe last year?
You could also use just pentagons and make a dodecahedron. There are actually many ways to divide up a sphere.
Do a google search for geodesic.
 
Upvote 0 Downvote
A geodesic dome is what I am going for.

What I am actually going for is to model the Spaceship Earth Sphere from Disney's EPCOT. I am modeling EPCOT in SW as a hobby and training.

I finished the monorail and now I am stuck on this geosphere. I am still searching for ideas. If anyone has any other ideas please let me know. It would be appreciated.

Thanks for everyone's help and input.

Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Upvote 0 Downvote
Penguin221,

Do you have your models posted anywhere on the web? I would like to see your work.
 
Upvote 0 Downvote
Upvote 0 Downvote
Whell, I don't know if this work but...
1 - imagine a sphere surface with center C and radius R
2 - imagine 3 lines L1, L2 and L3 intersecting in C
3 - each line define a point when intersecting the surface, that is all lines have length R from a given point C
4 - the angle between L1 and L2 should be equal to the angle between L2 and L3 and between L1 and L3
5 - the angle should be such that (360/angle)=integer
6 - the 3 points in the end of the lines define a planar triangular surface, which is a "segment" of a sphere
7 - do circular patherns of this surface around C

Can this work? I will give it a try!

Good Luck
 
Upvote 0 Downvote
macPT

I haven't quite understood your line of thought yet, but will try to figure it out and see if it works.

Thanks

swcadman

I have been to that site. The problem I am hving the most trouble with is creating what I need in SW. I think I pretty much have the whole understanding of how a geosphere is designed and works, I just can't figure out how to create it in SW.

Stephen Getsy
Product Development Engineer
Silgan Plastics
 
Upvote 0 Downvote
penguin,

Thats pretty cool, I wish I had some time to play around with that. Keep us posted!!
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

K
  • Question Question
Solidworks Assembly - Using Mass Properties of part instance to control dimensions of parts in assembly
Replies
3
Views
3K
jassco
jassco
V
Problem to open a .obj file with the textures visible on the model in Solidworks 2022
Replies
0
Views
33
victor andreevich
V
CAD2015
  • Locked
  • Question Question
Rotate a view in the direction of a line..................
Replies
17
Views
1K
jassco
jassco
jassco
  • Locked
  • Question Question
Solidworks VBA to GET and SET dimensions on a sketch in an assembly model
Replies
1
Views
2K
jassco
jassco
CAD2015
  • Locked
  • Question Question
How to count the components in a SolidWorks assembly?
Replies
8
Views
2K
CAD2015
CAD2015

Part and Inventory Search

Sponsor

Back
Top