Ghost or Phantom snap points

[Anonymous]

Hi

I have spent the last 2 days trying to draw a polyline but cant get it to snap to the correct location, the line keeps snapping to what I call phantom snap points in my drawing.

I have tried turning on/of various snaps in osnap along with the 3d snap, turned on/of "Magnet" in settings and resized the snap aperture box and selected various viewpoints.

I have reset Autocad to default settings on several occasions, copied my drawing into a new one with the same result.

Un fortunately this is not the only instance that I have had this problem.

I am using Autocad 2018 Educational Version on a Windows 10 machine.

Any and all help will greatly appreciated.

The fossil

[imadHabash · Accepted solution]

Hi,

would you please attache here your 3d blue line , for testing ?

[andkal · Accepted solution]

If there are any phontom objects in the drawing you can get rid of them by running AUDIT

[Anonymous · Accepted solution]

Hi Imad

Thanks for getting back to me.

I have attached the drawing, with the red circles, top one is the point I want to snap to and the other is the where the line actually snaps to.

[Anonymous · Accepted solution]

Hi Andkal

Will give it a try.

[fatal.error · Accepted solution]

The polyline's elevation value (origin and end point) is set to -3646.95, while the circle's centerpoint where you're trying to snap to have a Position Z value of -3748.98.

Since there are different non-coplanar Z-Values, you need to draw a 3D Polyline instead.

Try the attached file where I drew a magenta 3D Polyline on top of the original red Polyline.

Furthermore, after clicking a polyline vertex, you can press SHIFT + RIGHT-CLICK to show a menu where you can temporary enable/disable snaps:

Lastly, you're not working on the default WORLD UCS. To restore it, try typing UCS and then W.

Sometimes the Dynamic UCS get things messy. Press the F6 key to enable/disable it.

[imadHabash · Accepted solution]

Hi,

Thanks for your CAD dwg . i open it and try snapping here and there and nothing weird found !! for that i suggest to select just one osnap mode for use no more , any changes ?

[Anonymous · Accepted solution]

Thanks for that, I can now draw my line where I want.

The new problem, When I extrude the 3D poly line It doesn't extrude as a solid but as a mesh.

Same thing in other parts of the drawing where I have 2 entities on different planes, one a poly line, the other a 3D poly line. When I loft these two together they are not solid but hollow.

Cheers

[imadHabash]

>> When I extrude the 3D poly line It doesn't extrude as a solid but as a mesh.

check MOde option in Extrude command . 

Command: EXTRUDE
Current wire frame density: ISOLINES=4, Closed profiles creation mode = Solid
Select objects to extrude or [MOde]:

[Kent1Cooper · Accepted solution]

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@Anonymous wrote:

....

The new problem, When I extrude the 3D poly line It doesn't extrude as a solid but as a mesh.

....

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If you need to use a 3D Polyline instead of a 2D one because the points are not in the same plane, then presumably you will get a result that itself does not lie in a plane.  If that's the case, you cannot Extrude it into a Solid, regardless of the MOde option you choose in the Extrude command.  A 3D Polyline must be flat  to be able to Extrude into a Solid.

[fatal.error · Accepted solution]

As @Kent1Cooper stands, all of the 3D Polyline vertices must be in the same plane (coplanar). You can check it by converting that 3D Polyline into a Region. If you get "0 Regions created" as result, the vertices are non-coplanar or the loop is not closed.

[Kent1Cooper · Accepted solution]

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@fatal.error wrote:

... all of the 3D Polyline vertices must be in the same plane (coplanar). You can check it by converting that 3D Polyline into a Region. ....

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Another way to check:

(vlax-curve-isPlanar (car (entsel)))

and pick on the 3D Polyline [or anything else that qualifies under the (vlax-curve...) functions].  It returns T if the object is planar, nil if not.