# Fill in missing boundaries on group of curves?

**URL:** <https://forum.dynamobim.com/t/fill-in-missing-boundaries-on-group-of-curves/33954>\
**Category:** Uncategorized\
**Created:** [March 25, 2019, 8:57pm UTC](https://forum.dynamobim.com/t/fill-in-missing-boundaries-on-group-of-curves/33954 "2019-03-25T20:57:09Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ericabbott](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ericabbott/32/68658_2.png) [@ericabbott](https://forum.dynamobim.com/u/ericabbott)\
**Post date:** [March 25, 2019, 8:57pm UTC](https://forum.dynamobim.com/t/fill-in-missing-boundaries-on-group-of-curves/33954/1 "2019-03-25T20:57:09Z")

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Is anyone aware of any methods to generate curves to close a list of curves? Convex hulls do not work because of where the lines go inward.

Start geometry:

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/8/9/890fa1aefa1710e3d5c97aa1c12aca554ae637d7.png)

Desired geometry:

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/4/a/4af3436940c64352e1fc6860f48171fa83614d4c.png)

Any ideas? Thank you in advance!

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**Author:** ![Michael\_Kirschner2](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/michael_kirschner2/32/75576_2.png) [@Michael\_Kirschner2](https://forum.dynamobim.com/u/Michael_Kirschner2)\
**Post date:** [March 25, 2019, 10:06pm UTC](https://forum.dynamobim.com/t/fill-in-missing-boundaries-on-group-of-curves/33954/2 "2019-03-25T22:06:43Z")

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> **[Alpha shape](https://en.wikipedia.org/wiki/Alpha_shape)**
>
> In computational geometry, an alpha shape, or α-shape, is a family of piecewise linear simple curves in the Euclidean plane associated with the shape of a finite set of points. They were first defined by Edelsbrunner, Kirkpatrick & Seidel (1983). The alpha-shape associated with a set of points is a generalization of the concept of the convex hull, i.e. every convex hull is an alpha-shape but not every alpha shape is a convex hull.
> For each real number α, define the concept of a generalized dis...

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**Author:** ![Michael\_Kirschner2](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/michael_kirschner2/32/75576_2.png) [@Michael\_Kirschner2](https://forum.dynamobim.com/u/Michael_Kirschner2)\
**Post date:** [March 25, 2019, 10:07pm UTC](https://forum.dynamobim.com/t/fill-in-missing-boundaries-on-group-of-curves/33954/3 "2019-03-25T22:07:47Z")

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> <https://stackoverflow.com/questions/16625063/alpha-shape-concave-hull-algorithm-in-c>