Yes, the Shell is made up of segments.
I think the default segmentation setting is 36.
If you don't mind messing with the Registry you can change it.
I see you are on the Mac.
I can show you where to change it in Windows, and hopefully you will be able to figure out how to do it on the Mac.
In the Registry, go to the following place:
Computer\HKEY_CURRENT_USER\Software\GRAPHISOFT\ArchiCAD-64\ArchiCAD-64 17.0.0 INT R1\GSModeler.
Here change the value of ShellMaxSegmentationNumber from 36 to 72.
Also, change the value of ShellMinSegmentationNumber from 36 to 72.
Then Exit the Registry Editor.
Then exit ArchiCAD and restart it.
Go to your Section and regenerate it.
The Shell should now be generated with the newly specified segmentation, giving you a greater resolution.
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