Unwanted curves along equator on a hollow sphere that disturb Voronoi cells

[Mengqi]

Greetings!

I want to create Voronoi cells on a hollow 3/4 sphere. But there are strange curves along the equator which disturb the result ---- they split the cells.

Does anyone know how to delete the curves… or to create a hollow 3/4 sphere without equator curves… or any other idea to get the correct Voronoi cells?

Thank you!
Mengqi

Voronoi sphere.gh (8.1 KB)
Voronoi sphere.3dm (3.3 MB)

[Mengqi]

[davidsmavrov]

If you just need the voronoi curves, then use Brep | Brep (BBX) component.
This will bypass the sphere seam problem.

For some reason I can’t download you Voronoi sphere.3dm file…

[Mengqi]

Hello David,

Thank you! but I need the faces of the 3d Voronoi cells. And the sphere is not just a surface. It has a thickness. Can you open this 3dm?

Voronoi sphere.3dm (3.3 MB)

[davidsmavrov]

The part with the faces will be shity… the whole issue comes because of the surface seam.

[Mengqi]

yeeees… is there a way to delete the seam? Or how can I draw the 3/4 sphere to avoid a seam?

[grbl9789 (greg.obj)]

voronoihalfsphere.gh (14.6 KB)

[Mengqi]

Thanks Greg! But the seam is still there… a vertical one…

[grbl9789 (greg.obj)]

Darn! Didn’t notice that. I think its just the way rhino makes sphere breps out of surfaces. What is the problem that you are having with the extra line? They still can be manipulated correctly:

[Mengqi]

I want to scale the faces of those cell. But after exploding the Brep the faces with the seam running through it will be cut

in two parts…

[grbl9789 (greg.obj)]

Have to create a script that figures out which ones are split and then joins them. I can do it later tonight, going hiking right now

[Mengqi]

Thank you so much and enjoy hiking!

[HS_Kim]

Join first your splitted faces on the seams before scaling them.

Voronoi sphere_re.gh (103.2 KB)

[grbl9789 (greg.obj)]

Yep! Almost exactly my solution

[Mengqi]

Thank you! But after exploding the edges and vertices from that seam come again…

[grbl9789 (greg.obj)]

Doesn’t matter if they are scaling correctly, no?

[Mengqi]

Hi Greg,

Yes, they’re scaling correctly.

However, what I finally need are the vertices from the scaled faces. I need those vertices to build a new mesh. Since the vertices are still on those faces it leads to the same result as when you haven’t joined them…

Here’s a screenshot of my final mesh. The red marks are from the unwanted seam.

[laurent_delrieu]

If you don’t need a full sphere you could use that
https://www.grasshopper3d.com/forum/topics/surface-from-curve-netwrok?xg_source=activity

[maje90 (Riccardo Majewski)]

You can avoid the seam on a sphere by using another sphere with the seam in another position:

In this solution for each voronoi cell it do a check: if there are intersection with the seam and the cell, the alternative surface is used:

Voronoi sphere_re.gh (11.2 KB)

[Mengqi]

Hi Laurent,

That’s great! Thank you! Wow, it solved all the problem with the seam!

I need to set the radius to exactly 5, but the result turns out to be somehow smaller. Do you know how I can solve this problem?