Unroll surface glitch - Rhino says its unrolling a surface ok, but where is it?

hi there. I am new to this forum and only have been using Rhino for a week or two.

I am trying to unroll a surface. when I use the unroll command, Rhino appears to unroll it ok. at least it thinks its ok as it says: ‘4 surfaces unrolled’. However, no 2d geometry shows up anywhere in my file as far as I can tell.

all layers are on and visible and no objects are hidden. and if I create and unroll a simple box in the same file, it unrolls ok, so presumably its my surface that is the problem, not the Rhino settings… but i don’t know what it is that Rhino doesn’t like about it, so don’t know how to proceed.

any one have any experience of this scenario ? and/or knowledge of what I can do to fix??

thanks v much

unroll_prob_pascal.3dm (77.8 KB)

Hi Jack - the results will be at the World origin - are your inputs way off in the distance someplace?


Also on the World XY plane.

hi pascal & david, i cant see anything at the xy origin. and if i check zoom extents can see nothing elsewhere either…

Hi Jack - can you send me or post the input surfaces?



Hi Jack, try ‘SelLast’ then ‘Zoom Selected’ straight after unrolling and you should see if the result is present.

brian, thanks for the suggestion. unfortunately, ‘sel last’ highlights the surface i selected to unroll, not any new result

yes, thanks Pascal. i just added the file to my post

Hm Command line reports

“Area is 874948.7533 sq millimeters (5807.87 % ) bigger after unrolling”

Trying one by one.
Oh. It’s all one kinky surface- this will not work - hold on…

So, with DivideAlongCreases to split the surface into the four surfaces (How was it made?), some of these unroll and one at least does not. I would split off the pointy ends of these and unroll them - use Split >Isocurve to split off the very tips of the surfaces. ShrinkTrimmedSrf the large part and UnrollSrf these. Basically, it does not like the singularities at the ends (UV compressed to a point).

unroll_prob_pascal_PG.3dm (207.4 KB)


@pascal thankyou very much for looking and solving¬! mystery solved. i’ll follow your instructions.