Sphere fitting

Replies to This Discussion

Permalink Reply by Andrew Heumann on February 21, 2017 at 2:29pm

There's a "sphere fit" component - you could use "Populate Geometry" or convert your surface to a mesh and extract the vertices in order to get a list of points, and then try to use sphere fit to pass a sphere through those points. 

Permalink Reply by Ingenerum on February 22, 2017 at 2:14am

Hi Andrew, that was straight forward!

I've tried this component but it seems that the results provided are not optimal, in the attached example, for instance, it would seem that any sphere with a bigger radius would give a better fitting, what do you think?

Attachments:

• sphere fitting 02.jpg, 32 KB
• sphere fitting 01.jpg, 22 KB
• sphere packing.gh, 27 KB

Permalink Reply by David Rutten on February 22, 2017 at 3:01am

Your surface is invalid. How did you make it?

Permalink Reply by David Rutten on February 22, 2017 at 3:15am

What Andrew suggested though was to use the populate component. You need lots of points for a good fit and populate is the easiest way to get them.

Permalink Reply by David Rutten on February 22, 2017 at 3:19am

I untrimmed and retrimmed your surface, it's valid now.

Do note that both circle and sphere fitting don't work very well if the points are very flat. The more the points are spread out across the entire shape, the better the fitting will be.

Attachments:

• spherepacking.gh, 27 KB

Permalink Reply by Ingenerum on February 22, 2017 at 4:10am

Hi David,

Thanks for your support, I have not been able to open your file, I get a warning telling that it has been done using a higher GH version than the latest available.

However I have reproduced your suggestions (untrimming and retrimming to get a valid surface and populating to get a lot more points) and I still get a pretty small sphere. I wonder if you get simmilar results in your definition.

If this is because the input freeform surface is too flat maybe I will have to find an alternative method.

Attachments:

• sphere fitting 03.jpg, 25 KB