# Intersection Two Open Polysurface

**URL:** <https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589>\
**Category:** Rhino for Windows\
**Tags:** rhino6\
**Created:** [August 24, 2020, 7:37pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589 "2020-08-24T19:37:25Z")\
**Posts on this page:** 14\
**Page:** 1

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**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 24, 2020, 7:37pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/1 "2020-08-24T19:37:25Z")

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Greetings,

I am Rhino newbie.  
Trying to boleanintersect two open polysurfaces in vain. No results.

I would appreciate any piece of helpful advice.  
Attached-please-find-file.

Many thanks in advance with my best regards

 ![BoleanIntersection-Rhino](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/b/d/bdb3d010298b6918b4d4456fa5b210b5e1933b7c.jpeg) .[AC-Surface Base-EX\_05.3dm](https://discourse.mcneel.com/uploads/short-url/lJG1vXiXSTHFmnMHrzbhBNWXVI5.3dm) (8.3 MB)

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**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 24, 2020, 7:57pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/2 "2020-08-24T19:57:48Z")

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Hi,

It looks like these polysrfs were generated from triangulated mashs. This creates many tiny trimmed surfaces that are bound to cause problems during boolean operations. I would suggest using standard [surface modeling tools](http://docs.mcneel.com/rhino/5/help/en-us/seealso/sak_surface.htm.) to rebuild surface 1 and surface 2 to be only as complex as needed.

Additionally, it looks like you have two open polysrfs. \_BooleanIntersect works on closed solids.

You might also be interested in the [\_CreateSolid](https://docs.mcneel.com/rhino/5/help/en-us/commands/createsolid.htm) command.

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<div class="post-metadata">

**Author:** ![davidcockey](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidcockey/32/732604_2.png) [@davidcockey](https://discourse.mcneel.com/u/davidcockey)\
**Post date:** [August 24, 2020, 8:02pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/3 "2020-08-24T20:02:01Z")

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Use the Intersect command to intersect two open polysurfaces.

Meshes can be intersected using the MeshIntersect command.

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<div class="post-metadata">

**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 24, 2020, 8:14pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/4 "2020-08-24T20:14:47Z")

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Thank you for your prompt response.

Alas none of your suggestions works here. The forms (surfaces) have been imported from Autocad which gives an error message and makes impossible to cut/trim/intersect those surfaces.  
Hoped to make it possible within rhino.

Is there any trick to intersect/trim those two polysurfaces, perhaps something unusual?

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<div class="post-metadata">

**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 24, 2020, 8:31pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/5 "2020-08-24T20:31:48Z")

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Notice that when you run the \_Intersect command as the model is, Rhino does not return one continuous intersection. This suggest there are errors in areas where there are gaps.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/f/3f34fd1ff3c13236d02608a2ac0d28a751ff25c7.png)

If You use the \_Scale1D command to stretch surface 2 and run \_Intersect again, you get a _better_ result but it still isn’t perfect.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/9/1/91fd8177bdbfcf9b33428b08552946198826e97d.png)

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/a/b/abb72fd3aba4548137ae4c03d530523b020caa1d.png)

Notice that the command line says that 9 intersections were found. This suggests the input geometry is still too messy for boolean operations. **For best results during booleaning, this intersection should return one closed polyline.**

![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/0/8/08cebde300e7aa349d98cb43bf27da54183084b1.png)

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/4/d/4d26abde9e40542aa24b4c2808189e5ebdd47fa9.png)

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<div class="post-metadata">

**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 24, 2020, 9:17pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/6 "2020-08-24T21:17:56Z")

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Thank you very much for your pictoresque guidelines.  
One more question, if you do not mind.

Hot to cut the polysurfaces (two here) with the obtained via intersect polyline?  
Shall I explode the polysurface?  
If yes how?  
Hot to create the surface or solid after from the remaining of exploded, if any polysurface?

Well three more then one questions.

Once more I do thank you for your helpfulness and indulgence.

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<div class="post-metadata">

**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 24, 2020, 9:55pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/7 "2020-08-24T21:55:55Z")

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> [@GThib](#):
>
> Hot to cut the polysurfaces (two here) with the obtained via intersect polyline

Use the \_Trim and \_Split commands.

> [@GThib](#):
>
> Shall I explode the polysurface?  
> If yes how?

You can try to explode the surface using the \_Explode command. If you do this, you will need to pick each individual surface to cut.

> [@GThib](#):
>
> Hot to create the surface or solid after from the remaining of exploded, if any polysurface?

There is more than one path to get here. The answer depends on your end-goal. These solid tools are going to handle all this. Take some time to understand how these tools work and what they need to be successful.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/4/7/476ec70f7e71de7914cac289888e832297102dff.png)

I am still willing to bet rebuilding both of these polysurfaces will yield the best results. Take polysuface 1 from your example: If you explode it, you’ll get **1,185 individual trimmed surfaces**. You can get this down to less than a dozen while still maintaining the integrity of your shape.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/8/a/8a527f04a4bbf73b4d4bb738e479473432b87e5b.png)  
The Help Tab is reeeeealy good for explaining how these tools work step-by-step.

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<div class="post-metadata">

**Author:** ![DiegoKrause](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/diegokrause/32/257432_2.png) [@DiegoKrause](https://discourse.mcneel.com/u/DiegoKrause)\
**Post date:** [August 24, 2020, 11:28pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/8 "2020-08-24T23:28:12Z")

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I suggest to redraw the main curves and model new surfaces from them:

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/b/3b2e28e9ce9d9bfea6e84184e3432051410d5460.png)  
also you are working very far from world origin which can lead to operation problems.

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<div class="post-metadata">

**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 25, 2020, 4:38am UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/9 "2020-08-25T04:38:41Z")

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I am deeply thankful for your suggestions. I do truly appreciate it.  
Indeed, the surfaces comes from Civil 3D and have to represent a plantation bed. The complication consist on different width of the soil surface.  
Than is why I’ve decided to use Rhino to complete the task. Not certain if Civil 3D will recognise the Rhino solid.  
The problem is I cannot improvise to much with the surface form.

I have attached a file with three polysurface that should form a solid.  
I cannot manage to get it. There is an error message - unable to create solid.

I would appreciate if you could take a look on that with the expert eye.  
Thank you very much.[Polysurface to Solid.3dm](https://discourse.mcneel.com/uploads/short-url/fyQTXXdFn0l1gJeJgWjvIUw5NI9.3dm) (5.3 MB)

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<div class="post-metadata">

**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 25, 2020, 5:07am UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/10 "2020-08-25T05:07:03Z")

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> [@GThib](#):
>
> Not certain if Civil 3D will recognise the Rhino solid.

You can convert a Rhino NURBS surface into a mesh using the \_Mesh command.

> [@GThib](#):
>
> I cannot manage to get it. There is an error message - unable to create solid.

In this case you can just use the \_Join command. If you then run the \_ShowEdges command, you can see where things aren’t joining properly. This is why the \_CreateSolid command doesn’t know what to do.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/4/f/4f3f3f8177f2b6dbca7bef6176de47bc269fe9e5.png)

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<div class="post-metadata">

**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 25, 2020, 6:16am UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/11 "2020-08-25T06:16:26Z")

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Thank you very much.  
As I understand you suggest to change the 3 polysurfaces into mesh.  
Then use the Join command to join all highlighted (ShowEdges) edges.  
And finally create a solid from the 3 meshes.

It is too late this night.  
Will give a try tomorrow morning. Hope not to bother you.

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<div class="post-metadata">

**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 25, 2020, 6:49am UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/12 "2020-08-25T06:49:16Z")

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> [@GThib](#):
>
> Then use the Join command to join all highlighted (ShowEdges) edges.  
> And finally create a solid from the 3 meshes.

When you zoom in on the naked edges highlighted by the \_ShowEdges command, you will see that there are gaps and overlapping edges. Once this is fixed, it will BE a solid.

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<div class="post-metadata">

**Author:** ![GThib](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gthib/32/674007_2.png) [@GThib](https://discourse.mcneel.com/u/GThib)\
**Post date:** [August 26, 2020, 7:06pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/13 "2020-08-26T19:06:58Z")

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> [@ryan.odom](#):
>
> Once this is fixed, it will BE a solid.

Well I wish I could fix it. I am on the stage of the situation shown on your picture.  
Cannot move edge pints of joined polysurfaces. Once moving a point all moves. Any clever command?  
Shall I convert joined polysurfaces to mesh (using a mesh command) and then try to move the points to close gaps?

I promise I will take my time to learn Rhino, by for now I need just to get a solid from those surfaces.

Thank you.

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<div class="post-metadata">

**Author:** ![ryan.odom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ryan.odom/32/766425_2.png) [@ryan.odom](https://discourse.mcneel.com/u/ryan.odom)\
**Post date:** [August 26, 2020, 7:53pm UTC](https://discourse.mcneel.com/t/intersection-two-open-polysurface/107589/14 "2020-08-26T19:53:01Z")

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> [@GThib](#):
>
> Shall I convert joined polysurfaces to mesh (using a mesh command) and then try to move the points to close gaps?

Yes, try to convert to a mesh and then \_FillMeshHole and \_MeshRepair