Overlapping Closed Polylines

[j.straughan]

Hi,

I'm trying to find out a way in which I can easily identify any overlapping closed polylines. 

I have approximately 250 closed polylines very close to each other but without zooming in on each corner (very time consuming) I can't see if they overlap. 

Is there a more efficient way to do this through a command or a lisp tool?

Many thanks

[rkmcswain]

I just tried this routine, it works by identifying the overlapping points.

[Kent1Cooper]

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@j.straughan wrote:

... identify any overlapping closed polylines.  ....

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That may depend on what you mean by "overlapping."  Does coinciding count [red, left -- portions of edges overlap], or do you mean only crossing [green, right -- enclosed areas overlap]?

EDIT:  Or, the variant on the left condition:  a vertex of one touches another [whether at a vertex or along an edge], but with no length of overlap of edges?

[j.straughan]

I tried to use that but couldn't get the lisp to work? I loaded it into AutoCAD but couldn't find out what to type in order to use the lisp? Could you please advise on that?

[j.straughan]

It would be mostly intersecting like shown on the right but in some fewer instances the lines may be coinciding like on the left.

[Kent1Cooper]

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@j.straughan wrote:

It would be mostly intersecting like shown on the right but in some fewer instances the lines may be coinciding like on the left.

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>Here< is something about that.  But it's for selecting two of them.  [You can find other related threads in the Customization Forum with a Search for things like "find overlapping Polylines," some of which (like that one) find touching and/or coinciding edges and some only area overlap.]

The linked routine from Lee Mac uses the same basic function to find the intersections, but takes multiple object selection and does the marking of them.  I think you want the variation called "Intersections in Set."  You would need to load the LM:intersectionsinset code there, and the "Test Program" below, and the LM:intersections code at the top of the page.  Then use the "interset" command name defined in the Test Program.

[j.straughan]

Thanks that is very useful.

With the Lee Mac one, do I load the three things you mentioned all as lisps and then use interset?

Thanks.

[rkmcswain]

@j.straughan  - you will need the first two functions below as a minimum. The last one is an example of their usage.

LM:intersections

LM:intersectionsinset

interset 

[vladimir_michl]

Do you mean overlapping polylines or overlapping segments inside the individual polylines? The SelfIntersect utility (freeware) may help for the latter problem. See:

https://www.cadforum.cz/cadforum_en/self-intersecting-polylines-and-polylines-with-duplicate-vertice...

Vladimir Michl, www.cadstudio.cz