Grasshopper

algorithmic modeling for Rhino

Hope you are all enjoying the new release.

 

Has anyone tried out the planarization or smoothing functions yet ?

I'm interested to hear how you are getting along if you are, or if you have any questions about them.

 

It's a direction for Kangaroo I very much intend to continue developing - and I am still getting to grips with the possibilities and experimenting with how different optimization and fairing forces work in combination with one another, so I would value your input and experience.

 

For those interested in some background reading material -

[1] http://www.cs.caltech.edu/~mmeyer/Research/FairMesh/implicitFairing...

[2] http://mesh.brown.edu/taubin/pdfs/taubin-eg00star.pdf

[3] http://www.pmp-book.org/download/slides/Smoothing.pdf

[4] http://graphics.stanford.edu/courses/cs468-05-fall/slides/daniel_wi...

[5] http://www.evolute.at/technology/scientific-publications.html

[6] http://www.math.tu-berlin.de/~bobenko/recentpapers.html

[7] http://spacesymmetrystructure.wordpress.com/2011/05/18/pseudo-physi...

[8] http://www.evolute.at/technology/scientific-publications/34.html

[9] http://www.evolute.at/software/forum/topic.html?id=18

 

At the moment the Laplacian smoothing is uniformly weighted, which tends to even out the edge lengths as well as smoothing the form, which is sometimes desirable, and sometimes not. It also tends to significantly shrink meshes when the edges are not fixed.

I plan to try some of the other weighting possibilities, such as Fujiwara or cotangent weighting (see [1] and [3]), as well as other fairing approaches, such as Taubin smoothing [2], Willmore flow[4], and so on. This also has applications in the simulation of bending of thin shells.

 

Planar quad panels are often desirable, but I'm finding that planarization forces alone are sometimes unstable, or cause undesirable crumpling, so need to be combined with some sort of fairing/smoothing, but the different types have quite different effects, and the balance is sometimes tricky.

There's also the whole issue of meshes which are circular (I posted a demo of circularization on the examples page), or conical (this one still isn't working quite right yet), and their relationship with principal curvature grids and placement of irregular vertices, all of which is rather different when the whole form is up for change, rather than having a fixed target surface [7].

I'm also trying to get to grips with ways of making surfaces of planar hexagons, which need to become concave in regions of negative Gaussian curvature (see this discussion)

and I hope to release soon a component for calculating CP meshes, as described in [8], which I think could have many exciting construction implications.

 

While there are a number of well developed smoothing algorithms, their main area of application so far seems to be in processing and improving 3D scan data, so using them in design in this way is somewhat new territory. There can be structural, fabrication or performance reasons for certain types of smoothness, but of course the aesthetic reasons are also often important, and I think there are some interesting discussions to be had here about the aesthetics of smoothness.

 

Anyway, that's enough rambling from me, hopefully something there triggers some discussion - I'm really keen to hear about how all of you envision these tools might be used and developed.

 

 

Views: 2196

Replies to This Discussion

Hi Daniel,

 

I did use planarization here in combination with springs to fair a bunch of curves.

I had a problem at the time because initial zero length springs were not supported, so I had to start from a distant planar mesh an pull it towards the curves.

I understand that this is not a limitation anymore? Unfortunately I don't have time right now to work on it.

I'll look into it in a couple weeks Ihope.

Cheers,

 

Fred

Daniel,

 

I've seen your updates and am yearning to dig into something, but alas it's not yet in the cards with the work schedule.  I dwell in the world of "construction implications" but I can try to get a Soumaya example going for fun... sometime soonish hopefully.

 

Thanks for the links, I'll have a look at the ones I haven't seen before.

 

If I have any questions I'll give you a call, 1-800-KANGAROO...

 

Hi Daniel,

I see what people can do with those portions of magic you give and It's simply amazing.

The thing is that I can barely do anything, I'm going crazy with planarize component for N vertices.

I did open a topic in this forum, but I got nothing. It's kind frustrating. I'm sorry about claiming your help, I'm sure that you are a busy man, but this will be my last chance.

I'm uploading the files, and I will always thank you if you could give me some tips (I have already looked after any documentation available in the forum about how to use Kangaroo planarize, but nothing...)

There was a user that simply told me that the component mightly didn´t work, but I don't know, I've tryed out with 0066 and 0074, the same...so it has to be another thing...you will see that I've tryed with almost any way I could imagine...

Thank you in advance. Antonio

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