Precision issues flattening spherical panels with custom patterns

[boschimichele93]

Hi everyone,

I need some help with a workflow for an inflatable fabric object. I’m using a sphere as a reference case. To prepare the patterns for cutting, I am dividing the sphere into several segments (gores) and making them developable.

I need to split these segments into sub-sections to apply different colors (material patterns). When I perform the split on the 3D double-curved surface, everything looks fine. However, since the panels must be unrolled or flattened for production, I’m struggling with the “graphic” projection. When I project the cutting curves onto panels that are not perfectly perpendicular to the projection plane, the resulting geometry on the flattened surface becomes jagged or distorted.

I have experimented with several methods in Grasshopper and Rhino, including:

FlowAlongSrf

Surface Morph / Spororph

Squish / SquishBack

Unfortunately, none of these approaches have provided a clean, smooth result that maintains the original design’s fluid curvature once flattened.

Does anyone have a reliable method to map these “cutting patterns” onto the developed panels while preserving geometric continuity and avoiding jagged edges?

I’ve attached the example file and some screenshots for reference.

Thanks in advance for any insights!

sphere_exemple.3dm (826.1 KB)

sphere_exemple.gh (18.7 KB)

[maje90 (Riccardo Majewski)]

Your mistake is that you made your pattern intersection with the developable element.
First make the intersection with the real inflated model, then project the intersections found to the developable element.

Rhino Unroller can take extra geometries and unroll them together with the main geometry you are unrolling.
… you can keep each of your elements as simple surfaces and unroll just the pattern intersection curves:

unroll details.gh (19.4 KB)