problem with ellipse geometry

[swapnilzoal]

i am facing problem with geomety of an ellipse
when i offset an ellipse, its geometry is lost....
i can not extend this new ellipse and it has many grip points unlike the original ellipse

[irneb]

You're absolutely right, offsetting an ellipse will change it to a polyline with a great many segments. Setting the PELLIPSE to 1 draws the ellipse as a polyline with a lot less segments, but still a polyline, the offset also creates less segments - but still incorrect.

The only way I know to get the ELLIPSE is to copy @0,0 then change the major & minor radii of the copy through Properties Palette.

See attached. Top-left is normal ellipse offsetted. Top-right is Polyline ellipse offsetted. Bottom is true ellipse copied & changed.

[arshiel88]

...The only way I know to get the ELLIPSE is to copy @0,0 then change the major & minor radii of the copy through Properties Palette.

Yes that's how we do it right. Is there any other way to do it? The ellipse created from offsetting a real ellipse is just a spline approximation obviously without a center and quadrant osnaps.

[ccowgill]

Yes that's how we do it right. Is there any other way to do it? The ellipse created from offsetting a real ellipse is just a spline approximation obviously without a center and quadrant osnaps.

no, there is no other way to do it.

[seant61]

A comment should be made that this inability to offset is based on the mathematical structure of ellipses; no true ellipse has a counterpart that is a continuous offset of itself (with the exception of a circle which is a special case ellipse). The ellipse formula will not allow it.

Offsetting the Major and Minor radius may produce useful geometry, but the offset distance will shrink away from the quadrants. A spline is the only option for a continuous offset.

[arshiel88]

A comment should be made that this inability to offset is based on the mathematical structure of ellipses; no true ellipse has a counterpart that is a continuous offset of itself (with the exception of a circle which is a special case ellipse). The ellipse formula will not allow it.

Offsetting the Major and Minor radius may produce useful geometry, but the offset distance will shrink away from the quadrants. A spline is the only option for a continuous offset.

I agree with that. Its just the structure of the spline (offset from an ellipse) that I don't like. The spline points seem to be at random. The spline is not symmetrical while it was supposed to be because the object where it was offset from is symmetrical.
Why can't it be a projected ellipse like the blue ellipse in my attachment. I think this would be easier to use (in 2D and 3D) on the designing part and surely much easier to plot in the site than a true ellipse or an ellipse-offset spline. Of course if we want the projected ellipse to be smoother, we need more points.