# IfcAdvancedFace: cylindrical surface with winding loops

**URL:** <https://forums.buildingsmart.org/t/ifcadvancedface-cylindrical-surface-with-winding-loops/2225>\
**Category:** Developers\
**Tags:** ifc4, nurbs, advancedbrep\
**Created:** [January 8, 2020, 11:27am UTC](https://forums.buildingsmart.org/t/ifcadvancedface-cylindrical-surface-with-winding-loops/2225 "2020-01-08T11:27:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![igor.sokolov](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/igor.sokolov/32/25_2.png) [@igor.sokolov](https://forums.buildingsmart.org/u/igor.sokolov)\
**Post date:** [January 8, 2020, 11:27am UTC](https://forums.buildingsmart.org/t/ifcadvancedface-cylindrical-surface-with-winding-loops/2225/1 "2020-01-08T11:27:56Z")

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Attached examples of two faces with winding loops.  
I did not find any application can read it and looking for developers response (well, maybe the issue is in my IFC)

![image](https://us1.discourse-cdn.com/flex016/uploads/buildingsmart1/original/1X/f374561be5a1643a8613c999a081275d663333ac.png)

[Face 1.ifc](https://forums.buildingsmart.org/uploads/short-url/bP8X5skf2Gmnt3I4h2eyrVOHkqz.ifc) (34.7 KB)  
[Face 2.ifc](https://forums.buildingsmart.org/uploads/short-url/44BujG1lIveD4IimKF3IoyJmYQT.ifc) (34.6 KB)

This is how I expected to see the files.  
[Face 1 solid RV.ifc](https://forums.buildingsmart.org/uploads/short-url/r5RnFkbwzeW5Wp3oh275bTaGP8L.ifc) (37.8 KB)  
[Face 2 solid RV.ifc](https://forums.buildingsmart.org/uploads/short-url/77wQQPD7UBsYAqsTQQT8OWNfaiO.ifc) (37.5 KB)

![Face 1 - expected](https://us1.discourse-cdn.com/flex016/uploads/buildingsmart1/original/1X/d6d30d6c35d398858cc15e30288eb54f29e8e176.jpeg)  
 ![Face 2 - expected](https://us1.discourse-cdn.com/flex016/uploads/buildingsmart1/original/1X/3a91d7e2fa3a09a7720ded40f4ae664fef222364.jpeg)

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<div class="post-metadata">

**Author:** ![igor.sokolov](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/igor.sokolov/32/25_2.png) [@igor.sokolov](https://forums.buildingsmart.org/u/igor.sokolov)\
**Post date:** [January 8, 2020, 11:42am UTC](https://forums.buildingsmart.org/t/ifcadvancedface-cylindrical-surface-with-winding-loops/2225/3 "2020-01-08T11:42:26Z")

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Generally who is implementing NURBS?  
Do we need separate forum thread with examples and discussion?  
@jonm, @Moult, @arechtorisz, @angel.velez