CAD tip # 10926:

Question

CAD

% platform category

Self-intersecting polylines and polylines with duplicate vertices.

Some DWG drawings may contain curves (polylines) with selfintersecting segments (creating loops), or polylines containing duplicate vertices - superfluous repeating vertices or "backing" (zig-zag, self-retracing, overlapping) segments or segment parts. Such polylines with non-standard geometry may cause different problems when processing (in 3D, for Civil objects, LISP apps, etc.), in older AutoCAD versions, even the AREA command failed on these.

To find any self-intersections and duplicate vertices, you can use the freeware utility CADstudio SelfIntersect, which can be downloaded from Download. Load the VLX file with APPLOAD, type the command SELFINTERSECT and select a polyline (or use "M" for multiple, or "H" for this help). The application displays any intersections (in green), duplicate vertices (in red), and zig-zag parts (retracing, touching - in yellow) with temporary marks (remove them by Redraw, [F7]/[F7]).

lwpolyline vertex node

Duplicate start/end vertex on open polylines may be OK.

NOTE: you can also use the LISP function:

(SelfIntersect [objname])

defined in this tool to check objects programmatically. Returns a number of problem points or nil.

ACAD

*CAD

27.5.2016 33091×

Comments Tell a friend

Prices - CAD eShop:

AutoCAD

applies to: AutoCAD ·

See also:
Tip 9185:	Fix problem of Areas on self-intersecting curves in AutoCAD 2013.
Tip 7648:	Area not displayed for some boundaries or hatches.
Tip 3202:	A closed polyline cannot be extruded.

Selected tip: Text linked with Inventor drawing view.

Back All CAD Tips

Using assemblies in Inventor LT. « | » Which Autodesk products do support the IFC format?

Have we helped you? If you want to support the CAD Forum web service, consider buying one of our CAD applications, or our custom software development offerings, or donating via PayPal (see above). You may also add a link to your web - like this "fan" link:

Text:

FAQ

Featuring:
Extend your AutoCAD LT productivity with our popular add-on
CADstudio LT Extension More info

Please use these tips at your own risk.
ARKANCE is not responsible for possible problems that may occur as a result of using any of these tips.

CADforum

Tips, tricks, utilities, help, how-tos and FAQ for AutoCAD, LT, Inventor, Revit, Map, Civil 3D, Fusion, Forma, 3ds Max and other Autodesk software (support by ARKANCE).

ARKANCE CZ (CAD Studio) - Autodesk Platinum Partner & Training Center & Consulting Services Partner

CONTACT:
webmaster.cz@arkance.world | tel. +420 910 970 111