bone microstructure and voronoi diagram... need help

Hello,

I would like to generate the TRABECULAR area in bone (on the picture) using Voronoi diagram (or cell, whatever) in the Grasshopper software.

I have a solid part file generated from micro CT data.

Can I have your comments on how to generate trabecular-like Voronoi structure ?

Replies to This Discussion

Permalink Reply by Kellan Shanahan on February 3, 2016 at 11:54pm

This is why this is the best tech support forum on the internet.

Permalink Reply by SSB on July 31, 2015 at 12:37am

Thank you Nik

I truly appreciate your help

And I have one more simple question.

You gave me the cylinder with trabecular-like structure inside.

Then, can I measure the volumetric fraction (that is, "the volume of the trabecular structure" divided by "the volume of the hollow cylinder w/o trabecular") of the trabecular ?

Thanks for your help,

SSB.

Permalink Reply by Nik Willmore on July 31, 2015 at 12:57am

Right click enable/disable the cylinder (BC) versus the lines (CC) Cocoon force components to create two meta-object meshes, one of only the cylinder and one of the entire object, and just use Mesh Volume on each one:

Permalink Reply by SSB on July 31, 2015 at 1:28am

Thank you so much

I just ran your BoneStructure.gh file you gave me above.

And I had a trouble with it.

I found a red coloured alarm on the COCOON REFINE box and it said

Solution exception:file or assembly 'PlanktonGh, Version=0.3.4.0, Culture=neutral, PublicKeyToken=null' blah blah ... file or assembly cannot be loaded.

What is the matter with it?

Too tough to get through for me...

Permalink Reply by Nik Willmore on July 31, 2015 at 1:40am

Disable or delete Refine and just run the output of Cocoon directly into a Mesh component so you can bake that.

You are missing another plug-in, merely.

If it needs Plankton, that's a novel type of mesh component that Refine probably uses internally, and it comes with Kangaroo, so install Kangaroo Physics 0.099 from here, and though you don't need Kangaroo 2 (yet), you could add that too:

http://www.food4rhino.com/project/kangaroo?ufh

No, it's not easy to get up to speed on Grasshopper, and a lot of these standard plugins most people already have so we don't even imagine our scripts might not work for you :-). There are not a million essential plugins, only a handful.

Permalink Reply by Kim hauer on July 31, 2015 at 11:16am

I'm sorry if this does not slot into the correct thread order: I think Nik's Cylinder and my Coral adaptation would make interesting 3D printed samplesI'm not sure if the Cocoon Refine is adding any value that the Cocoon comp. is not already taking care of geometry wise?

Attachments:

CoralStructure.gh, 12 KB

Permalink Reply by SSB on August 1, 2015 at 5:29am

Btw, what ar those green, sphere-like things at the very right?

Permalink Reply by Nik Willmore on August 1, 2015 at 6:10am

Custom Preview, that affords solid previews.

Permalink Reply by Kim hauer on August 1, 2015 at 10:58am

The point cloud, recognizes the geometric mesh boundary of the Bunny. But the Line comp. which draws a Line between 2 points is unaware that some connecting Lines may fall outside the geometry. Is there a GH script solution, capable of making that determination, ......not to draw those lines ?

Attachments:

BunnyBones.gh, 150 KB

Permalink Reply by Nik Willmore on August 1, 2015 at 2:34pm

Split the lines to find points near the end and perhaps also the middle then cull lines with points outside the mesh? Might be slow, especially since you'll have to generate many more lines to retain some in the ears by random chance. Or regenerate the same item with new random seeds until no midpoints are outside the bunny. That will take a year or two.

Better yet, don't fix a broken strategy. Just generate all the lines using a sphere or a box around the whole bunny, offset a bit bigger, then trim the lines with the bunny, though I only see trim for breps, which won't seem to accept a mesh.

I've converted the bunny to NURBS using the ZRemesher tool of Zbrush but it was too big to upload as a NURBS Rhino file, so here is an autosurfaced NURBS model created in Geomagic Freeform:

Attachments:

Standford Bunny Autosurfaced In Geomagic Freeform.3dm, 2.8 MB

Permalink Reply by Nik Willmore on August 1, 2015 at 2:53pm

Actually, the culling via trim strategy is doomed since it takes too many sticks (here 5000) to get any at all in the ears, and thus the body fills up, pretty much the opposite of what you want structurally:

Permalink Reply by martyn hogg on August 1, 2015 at 4:39pm

I always find this with the sticks-in-a-box approach... spend ages messing with cull patterns to get the right density in the right places before accidentally grafting something and running out of memory.

Perhaps a better approach would be to grow spheres inside the volume and calculate the lines where the spheres intersect?

DOH!