topic Re: Offset- object is not planar in AutoCAD Forum

Offset- object is not planar

Anonymous — Thu, 30 Mar 2017 03:13:14 GMT

Hi,

I ma trying to offset survey pickup centerline but it is giving me an error:

" The selected object cannot be offset.

To offset an object, all points in the object must be located in the same plane"

Any help please. Thank you.

Re: Offset- object is not planar

Vinayv4v — Thu, 30 Mar 2017 09:04:52 GMT

Hi,

You have got yourself a 3d polyline. The offset command cannot be used to offset 3d polylines. You have to convert it into 2d for offsetting.

Check the article below

goo.gl/FEhlxc

Re: Offset- object is not planar

Vinayv4v — Thu, 30 Mar 2017 09:19:57 GMT

Hi,

At the mean time you can use a LISP for doing the work. Here is one from cadtutor.net forum attached.

Just go through the articles for more details about LISP

http://www.cadtutor.net/forum/showthread.php?88178-Offseting-3D-Polyline

https://autocadtips1.com/2013/05/15/autolisp-advanced-polyline-offset/

Re: Offset- object is not planar

Kent1Cooper — Thu, 30 Mar 2017 13:21:05 GMT

@Vinayv4v wrote:

....

You have got yourself a 3d polyline. The offset command cannot be used to offset 3d polylines. ....

More than that, the object [whether it's a 3D Polyline or a Spline] actually does not lie all in a common plane. A 3D Polyline can be drawn all in a flat plane, and Offset can't work with flat ones either, but in that case you just get an ordinary can't-Offset-that-object message at the command line. That pop-up alert-style message only occurs [for me, here in Acad2016] when the object is actually not planar.

That means that if you do something to make it Offsettable, be aware that it will change it geometrically in some way in the process [i.e. move some vertex or vertices]. If you don't want that, you could flatten a copy of it into a 2D Polyline, and Offset that, assuming that will serve your purposes, but of course the result won't be the same [3D] distance from the original everywhere, as it would [in 2D] with a flat one.

Re: Offset- object is not planar

Anonymous — Fri, 31 Mar 2017 05:49:53 GMT

Hi Vinay, how do I convert 3d polyline into 2D

Re: Offset- object is not planar

Kent1Cooper — Fri, 31 Mar 2017 11:41:56 GMT

@Anonymous wrote:

Hi Vinay, how do I convert 3d polyline into 2D

FLATTEN. Or, since some people have trouble with that, you can try the routine here, or to overcome some of its shortcomings, one of mine attached at Comment #6 there [on the "Next" page of comments] -- it's posted around here somewhere, but I knew how to find it faster there.

Re: Offset- object is not planar

darrell_kennedy — Wed, 07 Feb 2018 16:05:02 GMT

PEDIT, Select Spline, Convert Spline to Polyline? Enter Yes, then you can offset it. controlled vertices vary depending upon what you want the accuracy to be, i typically state 10.

Re: Offset- object is not planar

kmullen4 — Mon, 07 Apr 2025 15:36:31 GMT

Hi Kent I'm currently having this issue. flatten seemed to work and the offset appears but disappears when I try to specify which side to put it on

Re: Offset- object is not planar

Kent1Cooper — Mon, 07 Apr 2025 16:21:04 GMT

Interesting.... I find that a 2D Polyline that was originally a 3D Polyline but has been Flattened behaves that way, even if the 3D Polyline source was all in the same plane to begin with. But if I draw a lightweight Polyline, and convert it to heavy 2D with the CONVERTPOLY command, or if I set PLINETYPE to make Polylines heavy 2D when drawn, Offsetting works as expected. I don't have any idea why, or how AutoCAD distinguishes 2D heavy Polylines that are conversions from Flattening 3D Polylines from those that have never been 3D.

The only workaround I can suggest is to EXPLODE, and JOIN back together, and if you need it that way, Convert to heavy 2D. Offsetting works after that, for me.

Re: Offset- object is not planar

Simon_Mathews — Tue, 08 Apr 2025 09:17:14 GMT

i use the pline-3d-2d lisp , use 'pl32' as the command to activate it once installed . simply click on 3d polyline and it converts it to a 2d polyline instead