help - I need to convert 3D arcs to 3D polylines

[chrisw]

Maybe there is a feature line option to do this, but I cannot find this.

I have a site that was created by others - it has 3d arcs in it and I need to convert these to 3d polylines.

[m_kingdon]

Have you tried the MAPCLEAN commend, with convert selected objects, arc to polyline?

[TerryDotson]

When you list these arcs, does the list information include ...

Extrusion direction relative to UCS:

... with values other than 0.0,0,0,1.0.  Also shows differing Z values?

If you post a .DWG file containing the arcs, chances are someone can convert them.

[Kyle-Evans]

What about using the PEDIT command to turn it into a 2D polyline. 

And then convert the 2D to a 3D polyline, although this makes a massive mess of it...

[TerryDotson]

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What about using the PEDIT command to turn it into a 2D polyline. 

And then convert the 2D to a 3D polyline, although this makes a massive mess of it...

Yes, the AutoCAD PEDIT Multiple option does a good job on converting them to polylines.  However (as you mention) the Civil3D 2D to 3D convert makes a mess (forgot the invert the bulge factors?).

[chrisw]

I tried all of the suggestions but still there is no good solution.

Maybe there is no workaround.  I need to convert these into a feature line.

[TerryDotson]

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I tried all of the suggestions but still there is no good solution.

Maybe there is no workaround.  I need to convert these into a feature line.

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If you were to consider third party add-ons, the Object Convert Type tool in DotSoft's C3DTools should convert all the arcs directly to 3dPolys ready to join into FeatureLines.  I say should because I haven't seen a drawing containing your arcs to determine the contents.

[AllenJessup]

Can you post a drawing with a sample off what you're working with?

[chrisw]

Here is a small parking area with 3d polys and the 3d arcs

[AllenJessup]

sorry to say. I don't see any way to use the 3D Arcs.

[TerryDotson]

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Here is a small parking area with 3d polys and the 3d arcs

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See if the attached is the results you need.

[cwr-pae]

It would be a little time consuming, but you can convert the 3dpolys to FLs, then trace the arcs with feature lines and join them in to single FLs. You could also trace the 3Dpolys and arcs at one time which is the way I would do this small lot.

Note that the 3d arcs and polys don't match up elevation wise.

[chrisw]

this seems like a good solution - what was the workaround?

[samir.rezk]

Hi @chrisw 

I am not sure how these 3D Arcs were created, usually, Arcs have one Center point elevation, the start and end elevations are not editable, so I am very curious to know how these were drawn?!

Because these are non-planer Arcs, there is no way to convert them to a Feature Line! However, I had a thought to MEASURE some AutoCAD Points along the Arc then trace over with a 3D Polyline. It is definitely time-consuming though. I recorded a short video to demonstrate. 

Hope this helps a little,

[AllenJessup]

Hi @samir.rezk 

The OP said they were "created by others". Possibly not in and Autodesk product.

I used to create non-planar arcs in the way-back, early 1990's. What I most often did was create a arc in the WCS and them us Align to match 3D points.

You can also create a UCS to create the arc in. But I'd think the arcs in question came from some other piece of software.

[TerryDotson · Accepted solution]

this seems like a good solution - what was the workaround?

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I used the Convert Figure Type tool in DotSoft's C3DTools, you are welcome to request a 45-day full working eval to convert these.  Reviewing the results, you may want to reprocess them with a smaller middle ordinate value for more vertices on the arcs.  We have seen these "extrusion direction" problems for 20+ years (the oldest drawing we have like this was in 1998), it often comes from Microstation we think.  It's actually valid geometry, just difficult to use in civil / plan situations.

Actually post #4 by "Kyle-Evans" came close to a built-in solution.  However, it fails to invert some of the bulge factors and several arcs flip inward <> outward, creating the mess he describes.

[Neilw_05]

I know Microstation can have arcs with different z coordinates at the ends. I suspect these arcs were the result of a file conversion if that helps. As far as I know, the only way to convert them to polys is to flatten them, thus losing the 3D coordinates.

[Neilw_05]

I am not at a workstation so I can't test this, but I am wondering if you could use cogo point tools to create points at the ends of the arcs, getting their elevations from the z values. Then build a surface from the points. From there you can flatten the arcs, convert to featurelines and assign elevations from the surface.

[AllenJessup]

AutoCAD can also have arcs with different z coordinates at the end. They're just a pain to create.

I like your idea of using cogo points. I'd suggest creating a point at the midpoint of the arc to make it easier to create the arc in the Featureline.

[AllenJessup]

I thought I might be able to do something with Cogo Points and crate a Proximity Breakline. But the program doesn't work with the arcs. I get a Breakline with 0 vertices.