Hey friends, I am currently designing a rooftop geometry, based on combined cylindrical surfaces. When I unroll these surfaces, although they are mathematically developable, I noticed, that there are area deviation from original to unrolled surfaces… Is it a bug? One surface generates a deviation …

Hi Matthias - testing this with a simple cylinder, the deviation is much smaller than that. Could you post a 3dm model that shows this issue? -wim

[image] niemeyer: One surface generates a deviation of 0.05% multiplied by 80 times gives me a deviation of ca. 4%… To much… If multiple surfaces each have a deviation of 0.05%, then the total deviation will be 0.05%. Percent deviation does not simply add for multiple surfaces. Total percen…

[image] niemeyer: When I unroll these surfaces, although they are mathematically developable, I noticed, that there are area deviation from original to unrolled surfaces… Is it a bug? Most likely your surfaces as modeled are not exactly developable. Post a .3dm file with an example of a surfa…

190704_Test Cylinder Unroll.3dm (2.8 MB) Dear David, Got your calculation. Attached you get the 3dm file. All surface are based on ExtrudeCrv. So should be 100% cylindrical. I tested: If i cut the cylindrical surface in a diagonal angle, than it generates the deviation in area calculation betwee…

[image] niemeyer: 0.05% multiplied by 80 times gives me a deviation of ca. 4% :smiley: Anyways, what is your precision set to? And the size of your mesh?

Hi Matthias - try setting the file tolerance to .001 before unrolling. -Pascal

Unroll developable cylindrical Srf generates Area deviation

Rhino Rhino for Windows

ivelin.peychev (IVELIN PEYCHEV) July 4, 2019, 3:44pm 6

Anyways, what is your precision set to?
And the size of your mesh?

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Unroll developable cylindrical Srf generates Area deviation

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