# Representation of canonical geometries

**URL:** <https://discourse.mcneel.com/t/representation-of-canonical-geometries/65867>\
**Category:** Rhino for Windows\
**Created:** [June 27, 2018, 1:04pm UTC](https://discourse.mcneel.com/t/representation-of-canonical-geometries/65867 "2018-06-27T13:04:41Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![istvan](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/istvan/32/105261_2.png) [@istvan](https://discourse.mcneel.com/u/istvan)\
**Post date:** [June 27, 2018, 1:04pm UTC](https://discourse.mcneel.com/t/representation-of-canonical-geometries/65867/1 "2018-06-27T13:04:41Z")

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Hi,

I was wondering that under the hood, canonical geometries like planes, cylinders, spheres etc. are represented as NURBS surfaces or does Rhino store them as canonical geometries?

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**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [June 27, 2018, 3:05pm UTC](https://discourse.mcneel.com/t/representation-of-canonical-geometries/65867/2 "2018-06-27T15:05:57Z")

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Hello - normally as planes, spheres, surfaces of revolution etc. not NURBS. Same for lines, arcs, polylines. That’s not to say that every instance of these will something other than NURBS - they cal all be represented as NURBS but where possible they are in the more compact form. There’s also Extrusions of course.

-Pascal

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**Author:** ![istvan](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/istvan/32/105261_2.png) [@istvan](https://discourse.mcneel.com/u/istvan)\
**Post date:** [June 27, 2018, 3:07pm UTC](https://discourse.mcneel.com/t/representation-of-canonical-geometries/65867/3 "2018-06-27T15:07:54Z")

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Thanks Pascal!