Mesh to NURBS

Replies to This Discussion

Permalink Reply by peter fotiadis on May 15, 2014 at 12:35am

Well... (ghx def) for a start the mapper attempts to get tomatoes and extract sardines. On the other hand the definition attempts to handle the issue with quads and triangles ... whilst there's a lot of GH add-ons that do that in the first place for you.

Anyway with some rework (and weaver bird components) the definition "works as intended" (it's not ready yet) but the big issue here is what you could do with a brep that is smooth/hard as nails (compare with the RhinoResurf output).

On the other hand if your goal is to extract a proper nurbs out of a mesh...like the RhinoResurf command SingleSurfFromMesh (very slow when tolerances are reasonably low, mind) does....

... the definition requires some total rework (patch from extracted points does very weird things).

more in a while, best, Peter

Permalink Reply by peter fotiadis on May 16, 2014 at 12:56am

Apologize: I had plans to use WB in order to greatly simplify the whole ghx thing ... but other things happened and the rework must be postponed for a while.

In the mean time, get a slightly reworked version (all data are internalized) - NOTE: logic is redirected towards the patch component, but you can change it (it's a bit tricky: see orange circles) in order to use the original logic with (a) the sphere and (b) an added another test case of mine.

Anyway get the Rhino file (with the RhinoResurf result on the test mesh as well).

NOTE: a nurbs and  a "brep" (as attempted in the original definition) are NOT the same thing.

NOTE: Patch "attempts" to trim the nurbs ... but intentions and results differ.

best, Peter

Attachments:

• MeshtoBRepDefinition-MOD-A.ghx, 1.6 MB
• mesh-to-nurbs.3dm, 529 KB

Permalink Reply by Freeda Jane Madius on May 17, 2014 at 2:43am

Thank you for the help! Still getting used to using Grasshopper and getting acquainted with the tools. I really appreciate that you gave me your definition to look at and to study.

Permalink Reply by peter fotiadis on May 18, 2014 at 8:43am

Er...hmm...this was the definition that you provided.

This  is mine. Deals with the classic issue: you've got a terrain as a mesh (DTM) and you need a nurbs to work in a proper engineering way (solid ops for excavations etc etc).

Patch works but omits the trim - see the solution. You can rebuild (or not) the nurbs because large datasets and high accuracy are rather CPU taxing

Data are not internalized (load the Rhino file first, then the GH).

All levels related with the test data are turned off.

BTW: This is a real terrain :

Used for some parametric pedestal bridge (not made with GH - lot's of very complex classic solid operations required, like the concrete pathways etc etc).

best, Peter

Attachments:

• Terrain-Mesh-to-Nurbs-Peter34A.gh, 67 KB
• 233_China_BOTW_T34R.3dm, 771 KB

Permalink Reply by Freeda Jane Madius on May 18, 2014 at 12:49pm

Thanks for the definition and screenshots! :)

I'll be experimenting a lot with other plugins to see if I can come up with a neater definition if possible.

Permalink Reply by peter fotiadis on May 19, 2014 at 6:21am

Added some ways to get a better input for that Patch component (all inactive). WeaverBird, Kangaroo, MeshEdit used - but the best ways to relax/manipulate a mesh can be found in the Evolute Tools Pro and/or Geometry Gym.

Added the GH SplitSurface component instead the weird VBA thing.

If neater means less complex you can use clustering for creating a neat looking component and then store it (i.e. create an user object named, say,  "nemesis"). If neater means more clever ... hmm ... can I have the next question please? he he.

BTW: here's a more challenging terrain(mesh) > terrain(nurbs) puzzle (also real one). Choose one surface with no rectangular footprint, do a mesh out of it and pretend/assume that someone provided you with ...er...that mesh in order to work (say for designing some hotel properly "fused" into the landscape - meaning a lot of excavations and a certain dose of cost "fitness").

Attachments:

• Terrain-Mesh-to-Nurbs-Peter34B.gh, 78 KB
• 253_UAE_CBClub_terrain.zip, 3 MB

Permalink Reply by Freeda Jane Madius on May 20, 2014 at 3:26am

Thanks for the terrain! It will be a useful exercise for sure.

And I was thinking more in terms of a simpler definition? I'm not sure if that's necessarily a smart one though hahahaha XD I'm not a genius so I won't be able to make one that fast.

I really thank you a lot for your help! :)

Permalink Reply by peter fotiadis on May 20, 2014 at 3:48am

I do hope that nobody else reads this ... but..well... I'm a certified idiot (according ISO 9000) thus don't even mention the genius thing to me, he he.

Get the slightly reworked thing - proof that success is 99% failure (Soichiro Honda). Components (and the whole logic) used for the solid option (plan B) ... hmm... see ISO 9000.

Attachments:

• 253_UAE_CBClub_terrainB.3dm, 2.4 MB
• Terrain-Mesh-to-Nurbs-Peter34C.gh, 92 KB

Permalink Reply by peter fotiadis on May 20, 2014 at 7:28am

for 99% read 99.99% (use it with xxxterrainB.3dm)

Attachments:

• Terrain-Mesh-to-Nurbs-Peter34D.gh, 87 KB

Permalink Reply by Freeda Jane Madius on May 22, 2014 at 1:33am

Thank you again for your help!

And that quote about success being 99% failure is really inspiring. Thank you for that as well! :)

Permalink Reply by yj on May 2, 2016 at 12:20am

Dear Peter Fotiadis, Could you please post a screen shot if you still have this definition? looks like the kangaroo definition verion, which you said is classic, is not out versioned.

Permalink Reply by peter fotiadis on May 2, 2016 at 2:05am

Hmm ... this def is  prehistoric (nowadays is replaced by C# code > no native component of any kind around). It's a miracle that I've found it.

Anyway ... I've spend 2 minutes on that one by replacing the Kangaroo K1 thingy with C# code (the thing in the black circular group).

PS: Use as test the 253_UAE_.... 3dm file provided above

PS: Patch is tricky (one of the many reasons for using solely code to control what's happening).

Attachments:

• Terrain-Mesh-to-Nurbs-Peter34D2.gh, 142 KB

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