spheres returning invalid surfaces

Replies to This Discussion

Permalink Reply by David Rutten on February 28, 2015 at 10:43am

Yup, I can repeat that, and unfortunately the reason the Rhino SDK gives for the invalidness is not very helpful. I'll have to dig deeper...

Permalink Reply by Ethan on February 28, 2015 at 11:29am

ok thanks so much, It does seem to work if I change my rhino units to meters and scale down the number. My friend pointed out this issue with large numbers in computation ... http://en.wikipedia.org/wiki/Double-precision_floating-point_format

Ill have to read up on this issue more. It might be an issue in the sphere component because if I make the sphere small and scale it with the scale gh component it works, and also when I make a huge sphere in the rhino tools it works... when I make it with c# it is invalid also. Its weird because the sphere shows up but the data it returns is invalid....anyway thanks!!!  

Permalink Reply by Ethan on February 28, 2015 at 11:50am

I guess this same issue applies to the points being far from the origin as when I scale the points down to fit within the rhino grid the issue goes away. I will have to choose more appropriate templates from now on... I never thought that the greater the distance from the origin the less accurate rhino was but now I know... thanks E

Permalink Reply by David Rutten on February 28, 2015 at 11:54am

Well, mathematics with large numbers is problematic, but your numbers aren't that large yet. A couple thousand shouldn't pose a problem. A couple billion shouldn't pose a problem either.

This is more likely due to numbers that are much larger than the tolerance settings, but I'm not sure about that yet. If your spheres are several thousand units large, and your tolerances are set to a thousandth of a unit, that's quite a big range of numbers in which Rhino has to make sure all the geometry is accurate. Still, I'll let you know when I find out more, and if scaling the geometry down works in the meantime, you should probably do that...