# Surface continuity

Hi, I am exploring a little bit some theory regarding surface continuity.

In electronics we can often appreciate the imperceptible radius between surfaces. I.e Apple:

I have been trying, just with a simple mockup, to make the Zebra analysis continuous:

Unfortunately cube’s corners seem to brake the reflection. As always there is something to learn here and to ask you. I am sure I am lacking theory to understand this.

My procedure:
1.Made 4 arcs (degree 3) with a gap between them in order to play with blending options
2. Try all the blending options between curves: Tangency, Curvature, G3 and G4.

Do you know any tutorials or videos online that explain a little bit more about the principle of this?

The file is attached, I will keep researching the manual. But wanted to share this , cause usually users have great insights about theory.

All the best and thanks a lot for your time and consideration .

Blending.3dm (3.2 MB)

The corners you have there are a bit small to even see the difference between different approaches.l

The puffy corners on Apple products, for example, aren’t made with anything so pedestrian as an Arc. They’re sculpted with brute-force point-pushing, for hours and hours until they are just so.

Thanks Jim! , So do you think the dimensions of my blends are too small to make the zebra continous?

Do you mean the print screen or the actual file I uploaded? I am trying to learn about it.

Well on the screenshot they all look about the same. In the file you can see the differences more clearly if you use the CurvatureGraph tool, and then if you look really closely see the differences in the zebra display. The G4 one is smoother, the question is the difference in the shape between it and the “curvature” one bigger than the tolerance of the machine tools used to make the mold?

I guess then is not possible to see a continuous zebra?

The Zebra is continuous, what would you expect it to look like? It’s not going to be a flat line all the way across, that’s not how it works, where the curvature is tighter the stripes will be tighter, the idea is to get them to change as gradually as possible. To really get the ‘Apple’ look you need to NOT use Arcs or flat surfaces anywhere since their curvature is constant, and do some manual tweaking.

The render you’re trying to compare, there isn’t even really enough reflection information to say that it’s not just a filleted box, or a handmade 2D illustration.

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Thanks Jim, I did not know that about Zebra. I thought the “continuous” surface should have like a flat line. Regarding the apple effect, was just to exemplify the product design smooth meeting between surfaces.

Zebra display, like all shaded or render displays in Rhino, uses a mesh. If the mesh is too coarse details will be obscured and artifacts such as gaps along curved edges can appear. In Rhino for Windows the Zebra command includes the ability to adjust the mesh.
https://wiki.mcneel.com/rhino/meshfaq

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