ZBrushCentral

Sphere with a Mobius twist

ZBrush Usage Questions
#1

Hi all,:smiley:

I have been given a project by a company who would like me to model a sphere…But this comes with a twist…literally. The sphere has two holes each side which seem to fold in and twist in between in a unique way that seems to have baffled the company I am working for.

I have set up this thread just to get advice off people in terms of how they would go about modelling it especially as I feel that not everything meets the eye with this shape thus needing careful attention. At first i tried using maya although due to its very organic nature with a so called “mobius twist” it felt more natural to try moulding it into shape in Zbrush to get the twist right.
This has worked well although due to being new to Zbrush and having not modelled such a simple yet complex shape, I feel that it is best to know what everyone else’s views are in how they would model it.

Finally, it has been said that may be some kind of mathematical formulae for this to be generated automatically. Even though I am not a qualified engineer, i would be interested to know what this could be. I have uploaded a couple of images for you to share your thoughts. Any advice you can give me will be greatly appreciated. :smiley:

Attachments

Image 1.jpg

Image 2.JPG

#2

I think this would be very tricky in ZB. But I couldn’t resist trying it in Blender.

This one is single-sided and the mirror image of your example…

G.

#3

Hey man, to be honest having tried it in Zbrush it is very tricky and hard to keep symmetry so i am back in maya now as I feel there must be a very accurate way of twisting the geometry. I like ur example mate as it seems very accurate and symmetrical. I take it there is a tool that allows you to do this easily is there?.

Would you say i was right in starting off with 2 holes side by side and then creating the twist? Would love u to talk us through how you did this mate.

#4

Sorry I should have told you how I did it. I used Blender. Found it was pretty easy. Pretty much how you’d do it working in clay. Blenders interface
takes a little getting used to, but its still a lot easier than using ZB
for base mesh work.

I started with a ‘sphere’ exported from ZB. It was actually a cube
subdivided down to an ‘approximate sphere’ (so all quads).

In blender:

  1. I cut one half of the sphere off and added a mirror modifier. That
    way I only had to edit one side for the ‘hole’.

  2. I cut the hole by deleting vertices. (I experimented with using boolean
    operations, but that tended to mess up the quads). Did a little clean up
    to get back to an approximate circle on the hole.

  3. Then I ‘extruded’ the sphere surface inwards to give it some thickness.

  4. I ‘Applied’ the mirror mod’ to get back to a compete sphere (+2 holes)

  5. I cut through the strip between the two holes.

  6. I rotated the first row of vertices on one side 90-degrees, then rotated
    the second row of vertices 45-degrees. Repeated for other side, but rotating in the opposite direction.

  7. Welding job to join the strip back together. Export back out as OBJ.

Back in ZB:

Clean up a little using the move brush.