DWG curve has no curvature graph despite ramp up scale etc

received a dwg file and so as to assess quality of the work I select the first large curve on ortho view, run CurvatureGraph command and see no graph, increase the settings and still nothing.

is this normal ?

here it is.
dwg curve no graph.3dm (26.0 KB)


Hi Steve - it is normal of the curve is a polyline, which has no curvature.


Hi, file now attached.


I suspect if you Zoom in on it, you’ll find it is a polyline made of of short, flat segments so as CurvatureGraph shows, it has no curvature. AutoCAD does not support NURBS curves. You’ll need to replace the curve so it is actually curved.
Depending on the shape, you
may use Rebuild, RebuildCrvNonUniform, or manually replace it.

I see it is an open polyline 21 points

Oh cripes, its an aircraft from which to create lots of wooden frames for someone by extruding as solids, half slotting etc.
and sending the original curves off to the millers where no slotting required.

Do I have to redraw all the curves ? I see another has a graph, but its not a good curve ! they didnt use a graph !

AutoCAD and its segments drives me nuts. having to redraw items received in the past.

Do the curves look like this when drawn in autocad , or is it when rhino tries to open them ?


Actually, AutoCAD does support NURBS curves. It’s just that every (almost) AutoCAD user is so damn afraid of them that they facetize them as quickly as they’re found.

Steve, this may be of help: http://docs.mcneel.com/rhino/5/help/en-us/commands/curvethroughpt.htm I guess you would want the Interpolated option.


Perhaps if they stopped calling them “splines”…

FitCrv can be used to convert a polyline with many segments into a higher degree curve. http://docs.mcneel.com/rhino/5/help/en-us/commands/fitcrv.htm
When the input to the FitCrv command is a polyline, the FitCrv command treats the polyline vertices as a list of points, and it tries to compute a curve that goes near the points but has a reasonable number of control points. The FitCrv command is meant for polylines with many closely spaced points.