AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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Registered: ‎09-14-2012
Post 1 of 10

Surfaces by Boundaries

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09-14-2012 04:45 AM

I am trying to make a surface.

One can use Point, Drawing Objects or Boundaries in Master View.

When I pick a 2D polyline or 3D polyline to add as Boundaries I receive "Error adding boundary".

How can I define a line or polyline 2D or 3D as a Boundary in order to build a surface?

 

Thanks!

 

   

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Post 2 of 10

Re: Surfaces by Boundaries

09-14-2012 04:54 AM in reply to: akbarg

A boundary is a way to limiit the extent of a surface, e.g. created on a Dem basis.

So you BEFORE build the surface, and AFTER you add a boundary...

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Post 3 of 10

Re: Surfaces by Boundaries

09-14-2012 04:59 AM in reply to: antoniovinci

You mean that the surface should be there already, before one can pick a boundary in order to make a new

surface?:smileysurprised:

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Post 4 of 10

Re: Surfaces by Boundaries

09-14-2012 05:14 AM in reply to: akbarg

It should be better, although here's an (italian) trick to get a surface from scratch:

1] draw a rectangle and explode it

2] command _EDGESURF and pick on the 4 borders to create a Coon mesh

3] explode the mesh, to obtain a 3Dfaces' bunch

4] now make a new surface definition, adding those 3Dfaces under "Drawing objects"

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Post 5 of 10

Re: Surfaces by Boundaries

09-14-2012 07:15 AM in reply to: akbarg

When you see this error it means that the object you have selected as the boundary has geometric errors (null nodes, zero length objects, overshoots, not closed, etc.).

 

Select the bad pline. Use the properties dialog or PEdit to force closure on it and then run the Boundary command inside the bad pline. You should get a good pline in seconds. Erase the old and readd the boundary.

 

Mapclean is another option to fix the bad pline. You can also use lineworkshrinkwrap but if you boundary has overshoots or bowties the new pline may also have errors.

 

You can also try to set the maximum triangle length in the surface properties in order to avoid using a boundary. Search this newsgroup for more on that.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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Post 6 of 10

Re: Surfaces by Boundaries

09-14-2012 07:18 AM in reply to: jmayo

Oh sorry Antonio. I read his post too fast. You are correct, there must be surface defining data first. If you get the error after adding data my post is valid.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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Post 7 of 10

Re: Surfaces by Boundaries

09-14-2012 07:37 AM in reply to: akbarg

Thank both of you!

My mistake was trying to redefine a polyline as a boundary.

The surface than would be made of this boundary.

But as you two explained first the surface and then the boundary!

(the story of chicken and egg!)

 

The Surface can be made of Contours, DEM Files, Drawing Object and Point.

Boundaries and Breaklines should not be placed under "Definition" as they are in Toolspace! 

It is misleading!

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Post 8 of 10

Re: Surfaces by Boundaries

09-14-2012 07:43 AM in reply to: akbarg
To get a surface with whT you have, add the pline as a breakline first and then use the same pline as a boundary if required. Sent from my iPhone
John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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Post 9 of 10

Re: Surfaces by Boundaries

09-14-2012 08:36 AM in reply to: akbarg

If you're coming from a Land Desktop background, I seem to remember that you had to add the boundary first in that program.  Not so in Civil 3D.  Build your surface from points/breaklines/3D faces or whatever you have, then add a boundary afterwards.  Use a closed, non-intersecting polyline.  I've used 2D or 3D, destructive or non-destructive.


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Post 10 of 10

Re: Surfaces by Boundaries

09-14-2012 08:42 AM in reply to: akbarg

akbarg,

Breaklines certainly are definition, you  can build a surface from them as johnm just described.

 

Boundaries maybe are a little confusing, but they do define the edge of the surface.  You can't create a surface from just a boundary, but they do add data.  You can think of it as horizontal definition, just not vertical.


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