Fixing Invisible Trimmed Surface

Rhino Developer
1

invisibleSurface.3dm (74.2 KB)

This trimmed surface is invisible except for its perimeter edge and I cant figure out why. The surface seems fine in NX, and AutoCAD. The surface was imported into Rhino from a step file and perhaps the conversion from step is breaking it.

When trying to fix it, I used untrim KeepTrimObjects=Yes. This gives me curves. Sometimes (seemingly randomly) I can then split the surface with the trim curves and It looks fine. Other times the split fails (on the exact same geometry). The trim curves look fine. The trim curves do however have 5 segments, but after explode I get 9 pieces (very strange).

Does anyone know what’s wrong with the surface? Is there a way that I can repair it programmatically?

2

Hi Nick,

If you explode the trim curve you get a very short straight section where the control points are in line but not in order.

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image897Ă—729 80.8 KB

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image897Ă—729 2.53 KB

If you delete that, the remaining pieces are close enough to rejoin without needing to replace the removed part. The trim curve then needs to be pulled onto the surface for the trim to work, after which you have a “normal” surface.

image
image897Ă—729 70.5 KB

HTH
Jeremy

1 Like
3

Ahhh, I see. Its so tiny that I must have missed that little curve. Thanks Jeremy!