Solid v. Poly Surface Lofting Inconsistency. Is this a Bug?

I created this in DYNAMO to see if i could do it. Well it turned out that i can.






I noticed a strange thing happening though when i tried loft solids along the the top and bottom of the trusses. When i used the Solid by Loft (using curves and guidelines) node, it wouldn’t follow the guideline:








When i used the Polysurface Loft command, it worked fine.








Any ideas?

The dynamo file is uploaded below

Truss Along Surface

Hey BTM,


This looks like a bug, seems like the guide curve is just getting ignored… Investigating internally w2014-10-26_2227ith bug MAGN-5177

BTW, this is a crap workaround, but if you really need a solid while we sort this out, you can patch the ends of your Polysurface.Loft with the 2 profiles, then create a solid from the enclosed surfaces:


Intresting Stuff, BTM…!

would love to be in your classes :slight_smile:

Hello BIMTroublemaker,

We have fixed issue related to Surface and Solid loft using Guide Curves. It is already available in Daily Build.

This fix will be there in next release.



Hi, this thread is a year old, but i´m having the exat same problem, solid byloft is ignoring the curve. If I try the polysurface byloft i get “CENTERLINE_SECTION_DOESNT_CUT_PATH – Section does not define a point on the centerline path.” Any ideas? 1 2


I´m using dynamo 0.9 with rvt2016

hard to tell, but, I don’t think your inputs are correct, - I think a list of lines as the guide curve will produce multiple lofts, try creating a curve from the line points, or a polycurve and using that as the guide curve.

polycurve by points and nurbs by point both give different errors. I get “CENTERLINE_NOT_G1_CONTINUOUS” when using polycurve and “BAD_UV_SKIN_DIR – Surface U and V derivatives are in the same or opposite direction.” when using nurbs

If i change the lacing to longest or cross product the error disappears, but the loft is still in a straight line