# Flatten of a (poly)surface

**URL:** <https://forum.dynamobim.com/t/flatten-of-a-poly-surface/82533>\
**Category:** Geometry\
**Tags:** revit, dynamo, civil3d\
**Created:** [October 27, 2022, 4:14pm UTC](https://forum.dynamobim.com/t/flatten-of-a-poly-surface/82533 "2022-10-27T16:14:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![genossealex](https://avatars.discourse-cdn.com/v4/letter/g/97f17d/32.png) [@genossealex](https://forum.dynamobim.com/u/genossealex)\
**Post date:** [October 27, 2022, 4:14pm UTC](https://forum.dynamobim.com/t/flatten-of-a-poly-surface/82533/1 "2022-10-27T16:14:20Z")

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Hi.

Is it possible to flatten a (poly)surface or pullontoplane without creating of curves before?

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/f/3/f3f39463119450cfc7380487792fc04ba412224c.png)

My surfaces are not flat and as you can see, if i merge them and want to create perimetercurves (i need an outline) i get “wrong” lines.  
 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/4/3/43b07b5bee8e66d3144cd425c2c973c719102853.png) ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/f/e/fe1caee968219c638e8f202d679f7dd9c3ac4602.png)

My hope is, that if i can flatten the surfaces so that they have the same elevation, the perimetercurve function will create a correct outline.

It seems to work with the polysurface in the back.

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/7/1/7168ea994c1c57878b6ed643da1b9b6cd4757611.png)

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**Author:** ![christian.stan](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/christian.stan/32/166296_2.png) [@christian.stan](https://forum.dynamobim.com/u/christian.stan)\
**Post date:** [October 27, 2022, 5:49pm UTC](https://forum.dynamobim.com/t/flatten-of-a-poly-surface/82533/2 "2022-10-27T17:49:53Z")

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Hello, I had to retrieve the contour of the surface before the projection [Even if the input is a geometry], it only accepts the contour it seems (comment with reservations)

 ![Capture d’écran 2022-10-27 193818](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/1/1/11c43f03c3facc1b599c87a2f7b30977649c381f.jpeg)

cordially  
christian.stan