Polylines conversion not working as expected

[J. Wallace]

Creating a site model from a .dwg file a surveyor sent. I had to join a few polylines to make sure that each labelled contour was one unit. When I go to convert these polylines to 3d polygons or NURBS I get the following results. I've not seen this before. Any thoughts would be very helpful. If I trace a new polyline it converts as expected. Thanks in advance for any help.
ps in the after image you'll note that I selected and converted only a few of the polylines.

Edited August 23, 2017 by J. Wallace
Added PS

[J. Wallace]

Another screen shot selecting just five of the polylines and converting them to NURBS or 3d Polygons

[Benson Shaw]

I've seen this before, too, but not for a while. Looks like the open polylines have hidden closing segments and places where they double back on themselves.  Maybe ??? the geometry drawn in ACAD was a start/stop process with several polys added or composed or joined or whatever the process is called in other software, possibly with the various segments having different direction? Or the vwx import assigns the different directions? I ultimately gave up on the conversion.  My solutions were A. trace with 2d poly, then convert to 3d poly.  or B. Use Duplicate Along Path with a 3d Locus and the imported poly, then use the loci instead of the imported contour(s).  I usually keep a 2d source layer, or even a separate file, with all the imported geometry.  The DAP solution worked quickly for me, esp if each group of 3d loci was assigned to a unique class - name includes the z value - and color.  That way if the source data needs editing, I can visually differentiate and select/edit the various groups or points of z intervals.

 

Another thing to try is import the contours, then export then to dwg or dxf, then reimport them and try the conversion. It's just an idea.  No experience to show it would solve things.

 

-B

 

 

[J. Wallace]

@Benson ShawThanks very much. The dwg export import did the trick. I thought I was going to have to trace all the contours, happy to see this worked. When converting to NURBS I had three polylines fail to convert, I replaced these and viola...Thanks again Benson.

[Benson Shaw]

Welcome, but that export/import idea was totally a guess. Glad you could test and make it work!

 

-B