Sections are interrupted


The attached rhino file contains a surface that gives, at certain locations, interrupted Sections. See attached picture.
I have tested the surface and the loft curves (from which it is made) on double or crossed control points, but that is not the case. Who can help?

Sections not compleet.3dm (277.2 KB)

Cheers, Bas

Intersecting the hull with planes in the RH6 WIP seems to produce complete intersections:

I am working with students and the policy of the university is not to use beta versions. So this is not an ideal solution.

OK. That’s understandable and not ideal but there won’t be any updates to RH5…

Is there a work around? Has it to do with the accuracy settings?

what i tried is;

i have created a cutplane and cut the access parts at the starboard from centerline of the hull (you wont need them anyway, if you dont want to tweak the the hull surface further) after that it worked for me


I did the same, but intersect gives interruptions too on this shape. I have made many ship hulls and my students too, but this one is rarely strange.
See the rhino file: Sections not compleet.3dm (414.7 KB)

Cheers, Bas

Hi Bas - in V5 adding some knots in U in the more sparse areas of the surface (turn on isocurves) will help, but there is still a problem at the area of high curvature near the bottom - for some reason the intersector does not like it where the knots are at right angles to each other and the section cuts through (your more forward sections in red)


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hi there

i see that you have only created a cutplane but didnt cut the main hull surface. i did what i told you before and it works at my end.

Run the Reparameterize command using the “automatic” option, then try again.

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I used _Reparameterize on the loft curves and this does the job, but what does Reparameterize do? The Rhino help says:

  • " Recalculates an object’s parameter space to be roughly the same size as its 3-D geometry." and

  • The parameters values of the objects recalculate so that the parameter space of the objects is roughly the same size as the 3-D geometry of the objects.”

But this says nothing to me. I compaired the coordinates of some of the control points, but these seems the same.

Reparameterized Loft Curves V1.3dm (7.7 MB)

(In the attached file I moved the case with the interruptions to make both cases visible, so the control points are not the same… :wink: )

Cheers, Bas

Hi Bas - the ‘domain’ of a curve or surface, that is the range or size of it’s ‘parameter space’ can be any two (increasing) numbers - Re[arameterize lets you set those numbers and the Automatic option sets the numbers to something close to

0>3d size of the object.

For example, draw a new control point curve with a few points - measure its length and also its domain (Domain command). Then move points around to make the curve noticeably longer or shorter - the length will not longer match the parameter space domain of the curve which remains as it was when you created the curve…

Reparameterize > Automatic will reset that to match the length. Similar for surfaces though there of course its an approximation unless the thing is a simple rectangular plane since size is not constant.