topic Re: Polyline Arc to Partial Ellipse in AutoCAD Forum

Polyline Arc to Partial Ellipse

rcook — Fri, 18 Aug 2017 15:59:43 GMT

I had posted this about a year ago and never got any resolution. I haven't had this happen again until last week. I have had some arcs that have changed to an ellipse. What is causing this? Last time it was every arc in my drawing. This time it is only some of the arcs. I need to figure how to repair this or keep it from happening as it costs time to repair. I have attached a sample of the drawing. I have never used a partial ellipse.

Thanks for any help.

Robert

Re: Polyline Arc to Partial Ellipse

imadHabash — Fri, 18 Aug 2017 16:58:01 GMT

Hi,

it's sounds that tour drawing elements come from old version of autocad. i suggest to check PELLIPSE and PLINETYPE system variables and read about them from the Help ( F1). Hope it's help..

Regards,

Re: Polyline Arc to Partial Ellipse

john.vellek — Fri, 18 Aug 2017 18:13:13 GMT

Hi @rcook,

I am not aware of any reason that the arcs would be converted to ellipses. I did notice however, that Audit shows this sample drawing has 12 errors and -Purge>Regapps removed over 100 regapps.

Perhaps there is some corruption in the files that have this problem or perhaps even in your template files. Can you check this and report back?

Please select the Accept as Solution button if my post solves your issue or answers your question.

Re: Polyline Arc to Partial Ellipse

rcook — Fri, 18 Aug 2017 19:41:23 GMT

That's odd. I typically audit and purge to keep files clean. I just checked what I attached and I get no errors found and nothing to purge.

Re: Polyline Arc to Partial Ellipse

john.vellek — Fri, 18 Aug 2017 20:00:13 GMT

Hi @rcook,

The error checking is more intensive with more current product. Which version of AutoCAD are you using?

Re: Polyline Arc to Partial Ellipse

rcook — Fri, 18 Aug 2017 20:22:41 GMT

Autocad 2017

Re: Polyline Arc to Partial Ellipse

john.vellek — Fri, 18 Aug 2017 22:12:12 GMT

Hi @rcook,

My AutoCAD 2017 also does not find the errors.

Re: Polyline Arc to Partial Ellipse

rcook — Fri, 18 Aug 2017 22:34:20 GMT

Thanks for a comment. It helps to solve issues and helps to me to know I'm not that crazy.

Re: Polyline Arc to Partial Ellipse

Kent1Cooper — Mon, 21 Aug 2017 11:49:00 GMT

Have the Arcs/Polyline arc segments been parts of Blocks? If a Block is unequally scaled, and I think this may also apply if the X and Y scales are equal but the Z scale differs, then when that Block is Exploded, any Arcs become partial Ellipses, even if they have eccentricity of 1. I have had this happen if I change the scale of a Block not with the Scale command but in the Properties box, by changing the X and Y but not the Z, then later Explode it.

Re: Polyline Arc to Partial Ellipse

rcook — Mon, 21 Aug 2017 14:16:41 GMT

The arcs were originally in a polyline segment as an arc. I suspect some of what Kent1cooper said except that I did not (or at least realize) the I exploded anything in the drawing. The first time it happened it was global causing all arcs to become partial ellipses and the multileaders with text to become separate text lines and the leader to be an arrowhead and line. That is what made me suspect some type of explode command I was not familiar with. This particular instance only affected approximately six arcs all located close to each other and was not a big issue like last time. I will keep watch and hopefully someday it will be solved.

Re: Polyline Arc to Partial Ellipse

Kent1Cooper — Mon, 21 Aug 2017 16:32:17 GMT

@Anonymous wrote:
The arcs were originally in a polyline segment as an arc. I suspect some of what Kent1cooper said except that I did not (or at least realize) the I exploded anything in the drawing. The first time it happened it was global causing all arcs to become partial ellipses and the multileaders with text to become separate text lines and the leader to be an arrowhead and line. ....

Was FLATTEN involved? If you have arc segments in a Polyline that wasn't quite in [or parallel to] the current plane, they could become partial Ellipses.

Re: Polyline Arc to Partial Ellipse

rcook — Mon, 21 Aug 2017 16:58:41 GMT

Kent1cooper, good idea. I thought of that once before, but have not investigated that possibility. I received part of this dwg from another source and noticed their work had elevations on the lines so guess what, I flattened them. When I get time I may try that one out and see what happens. Thanks

Re: Polyline Arc to Partial Ellipse

john.vellek — Tue, 22 Aug 2017 19:48:22 GMT

Hi @rcook,

I am checking back to see if my post or others helped you with your problem. Please add a post with how you decide to proceed and your results so other Community members may benefit.

Please hit the Accept as Solution button if a post or posts solves your issue or answers your question.

Re: Polyline Arc to Partial Ellipse

rcook — Tue, 22 Aug 2017 19:51:42 GMT

I will go with it for now. I need to test the idea presented by Kent1cooper about flattening 3d arcs. I will do some testing on the idea when I get a chance.

Thanks to all

robert

Re: Polyline Arc to Partial Ellipse

Anonymous — Wed, 23 Aug 2017 02:03:41 GMT

hi rcook, if you need a plugin to convert between arcs/polylines and partial eclipses , do not hesitate to contact us, we can do it for you for free, 🙂 Thanks for your post.

Re: Polyline Arc to Partial Ellipse

PappaDale — Tue, 23 Mar 2021 21:41:21 GMT

I have had issues with arcs changing to ellipses after flattening them. I can recreate this in a drawing I received from an outside source (Architect/Planner) by drawing plines then fillet them then explode the pline then flatten. I only noticed this after it happened when I selected the newly joined lines and "arcs" turned into a spline. If I explode the spline it is now lines and Ellipses.

Flattening the exploded pline will convert the arcs to ellipses. Any Ideas why this would happen? I have audited and purged the drawing several times. I'm using Civil3D 2020.

Re: Polyline Arc to Partial Ellipse

guerripablo — Sat, 31 Aug 2024 04:44:54 GMT

I just came across this, and in my case it was cause by using "flatten" over arcs. When I do so, they became useless ellipses.

I haven't found a way to solve it.

Hope this helps.

Re: Polyline Arc to Partial Ellipse

Kent1Cooper — Sat, 31 Aug 2024 10:48:18 GMT

@guerripablo wrote:

.... in my case it was cause by using "flatten" over arcs. When I do so, they became useless ellipses.

I haven't found a way to solve it.

....

That happens only if the Arcs are not in or parallel to the current drawing plane. An Arc that is "skewed" in that way is not an Arc from the current point of view, so if the command would Flatten into still an Arc, it would need to change shape from the current point of view.

The only way to "solve" it is to have the Arcs comply with the requirement that they lie in or parallel to the current drawing plane, before Flattening, which will necessarily alter their appearance.