Reverse engineering, anyone ? GH lacking proper tools

I recently got an “Einstar” scanner, which I would really recommend for the price (under 1000 €).
Since I need Breps for CAM toolpath generation, I’m trying to fing good reverse engineering techniques and tools.
I tried the Sub-D QuadRemesh route, but that generally gives me way too many Nurbs patches and still requires quite a bit of manual adjusting.
For now, I’m sticking with drawing guide curves, creating rough Nurbs patches manually and them using these as base surfaces for the “Patch surface” command.

Of course, I wanted to automate as much as I could, but GH seems to lack all the good stuff that would allow it :
-The GH “PullCurve” component doesn’t accept meshes as an input, contrary to the Rhino component
-The “Geodesic” component doesn’t accept meshes as input. By chance the “MeshPaths” plugin solves that.
-There is no native Point cloud support, and the plugins (Volvox, Cockroach) don’t allow point cloud baking
-The GH “Patch” component is a watered down version of the Rhino command, and it doesn’t accept starting surfaces, making it quite useless, since this generally produces wonky worthless surfaces.

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I’m very familiar with this.

But you mean relative to Rhino specifically?

Yeah sadly it seems to be in it’s infancy.

I’ve been messing with it alot lately on a couple projects.

Also, I’ve been trying out the V8 WIP shrinkwrap tool.

I recommend a similar approach but possibly using network surface workflows.

Ikr. I wish things were automatic, but sadly nothing ever is – imo.

This outcome sounds all too familiar to me.

There’s a huge niche in this industry.

Recently I had terabytes of data become useless due to the NextEngine litigation.

I’m wondering what will fill the void in the years to come.

Hey Magic, would you magically post the C# component ?

Patch-a-saurus !

Yeah, that’s why I was looking for mesh geodesics !

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I’m not him, but this is just a matter of copy-pasting the names on the component…
2023-03-21 18_23_57-Window (9.6 KB)

Note that “fixEdges” require always 4 booleans as the documentation says:

Array of four elements. Flags to keep the edges of a starting (untrimmed) surface in
place while fitting the interior of the surface. Order of flags is left, bottom, right, top

sounds interesting, does it exist? seems like I came across that recently …

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That’s very interesting. I wonder if it can be used to place 4 points on a mesh and create a network surface that fits closely to the mesh. Hence, reverse engineering the mesh into nurbs :thinking:

I also have 2 geodesics components in Nautilus plugin. One from a point and a direction and one from point to point.
And it could be access with a library.


So this still works for Rhino7? It only makes reference to 4 thru 6.

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Thanks for crafting this, I was in a but of a rush yesterday.

@osuire Flexibility.GH plugin has pretty much all standard components upgraded with all parameters available from RhinoCommon. It has a full Patch component. It also comes with a ribbon full of awful icons. Make your choice :sweat_smile:.

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I choose the ugly icons, and not trying to fight with C#.
Thanks for this link !

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I suppose so, but with certain shapes, the geodesic curve can get funky / unpredictable.
Since I had already manually created my NURBS patches, I just created a definition that would project the isoparms on the mesh, and create Network surfaces from them.
Worked like a charm ! (18.0 KB)

Sorry, I can’t share the geometry itself as it is from a sculptor.


Can’t you create toolpaths from smoothened meshes?

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My sculptor likes his subtle sharp lines.
You know, the kind of car bodywork creases that vanish on a surface.
Moreover, I’ve heard that FUSION 360 doesn’t like meshes so much and will cause trouble with certain toolpath strategies, but to be honest, I never tried.


That’s awesome! I’m kind of in disbelief that I’m seeing what I think I’m seeing :exploding_head:

It almost looks as if you got Grasshopper to convert mesh to nurbs with really nice isocurve flow :exploding_head:

That’s understandable, while I would really like to see this develop into the horizon of possibilities per say.

That video is amazing :smiley:

I really need a solution like this.

Another really helpful aspect that needs to be solved imo is the ability to ‘align meshes’ from 3D scans. :coffee:

omg that would be so awesome too! :sweat_smile: :coffee:

fusion 360 is cloud based, and that is a violation of security imo – based on principle.


using Grasshopper? :upside_down_face:

Many things are possible. I don’t own a CNC machine or robot but I’ve done some toolpath simulation and exported curves and lines for machining mostly wheel-wells on downhill skateboards.