Unroll - Parabolic

[Strider75]

Is it possible to perform an unroll projection on a parabolic shape? Looking at the image I can see that it could possibly be developed in three parts but was wondering if there is an easier way?

Thanks for a great product,

Jim

[daniel]

The 'Section extraction' tool (http://www.cloudcompare.org/doc/wiki/in ... t_Sections) is able to unroll the cloud along a polyline. So if you manage to draw the polyline with enough steps so as to get a good approximation of the parabolic shape it could do the trick.

The issue is that it only does this internally. The extracted cloud is then ''folded' back so as to be at the right position in 3D (i.e. around the input polyline). I could hack the code and show you what it looks like 'unrolled' if you send me a sample dataset (cloudcompare [at] danielgm.net).

[daniel]

Ok this is now possible. Take a look at this thread;
viewtopic.php?t=1417#p5456

[Strider75]

Unrolled Stair using your new tool. Excellent!

[daniel]

AH! Nice indeed ;)

Thanks for the feedback!

[Strider75]

Note of caution when when using this tool. My procedure was to trace the polyline in autocad and import to cloud compare. If using curves in your polyline the tool extracts based on the chord of the curve (2nd image). If greater accuracy is required as in my case instead of using curves I just loaded the polyline with more vertices (no curves) to create a more accurate elevation view (first image). Thanks again!

[daniel]

Curves in polylines?! How do you do this? It is a particular Autocad entity?

[Strider75]

Autcad polyline created with arc sub-command. Upon closer inspection it gets imported as chords at the begin and end of the curves. I have sent an email with the dxf and resulting .bin file