Unable to offset polylines

[Luke_Daniels]

These road outlines were converted from splines into 3D polylines. FLATTEN command is not converting them the 2D polylines and I think for this reason I am unable to offset each of them 906 mm outwards. Can anyone advise on why these objects cannot be offset? see attached file...

[parkr4st · Accepted solution]

it appears as there a far to many vertices in the lines

On  new layer, draw splines with about ten equally spaces vertices along your lines.  the splines will offset with no problem.

Can you simplify your lines?

[will_young]

You can't offset because there are some near zero z value vertices and it won't offset a 3d poly (even though it shows a preview!).

I never have much success with FLATTEN, I usually explode and then set the elevations to zero before joining to create the 2d polyline as per the video.

Also you could OVERKILL as there were a lot of overlapping segments.

[Kent1Cooper]

As mentioned, even a geometrically planar 3D Polyline cannot be Offset.  That's one reason I made Pline3Dto2D.lsp, >here<.  See the comments at the top of the file.  I tried it in your drawing, and the results were Offsettable [without reducing the number of vertices].

[leeminardi · Accepted solution]

As others have said there are way to many vertices but if you want to use the 3dpoly then either use @Kent1Cooper  program or you can use the Boundary command to create a 2dpolyine.

For example, create a polyline (red) as shown below.

Using the boundar command pick a point inside the closed area.  This will yield a 2d polyline.

Trim off the extraneous geometry and then use offset as needed.

[Luke_Daniels]

Thanks Lee, much appreciated.