@kevinmoerman@fosstodon.org
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kevinmoerman

@kevinmoerman@fosstodon.org

Computational (bio)mechanics and design engineer

Assistant Professor Mechanical Engineering, University of Galway. Adjunct Senior Lecturer Griffith University.

#opensource #openscience #openhardware

Developer https://www.gibboncode.org/. Co-founder, Associate Editor in Chief JOSS.
Editor PLOS ONE, Journal of Open Hardware. Steering committee member EngrXiv.
Senior member IEEE.

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kevinmoerman, to random
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Smoothing methods compared. These show "constrained smoothing" i.e. I'm telling the algorithm to leave the bottom half alone.

https://github.com/COMODO-research/Comodo.jl/blob/main/examples/demo_surface_mesh_smoothing.jl

Surface smoothing methods applied to a noisy bunny rabbit triangulation. The noisy bunny looks all spiky. The aim is to use smoothing to retrieve the original smooth bunny. However, some smoothing methods cause shrinkage. Also half the bunny is here constrained from smoothing to illustrate that such constraints (holding on to points) can be added.

kevinmoerman,
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@metin Yes, probably*. You may have it already in Blender (I know Meshlab has it too for instance). It is called HC (Humphrey’s Classes) smoothing. Here is the paper defining the algorithm, it is easy enough to implement: https://doi.org/10.1111/1467-8659.00334/.

Email me if you can't access it (kevin.moerman@universityofgalway.ie).

  • It is not formally volume preserving but it aims to avoid the shape distortions seen for normal Laplacian smoothing by pushing nodes back a bit.
kevinmoerman, to Batman
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Coming soon to : constrained triangulations. Which I decided needs parameterized curves too for testing purposes 🦇

kevinmoerman,
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Getting there. These images show tests of a triangulation algorithm I've developed that uses Delaunay triangulation. It features mostly equilateral triangles except for at the boundaries.

Same as previous image but now the boundary is the Batman logo. This shape features sharp transitions which is good for testing how the algorithm copes with these.

kevinmoerman, to 3DPrinting
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This is a fantastic article on rotations and by the great Keenan Crane @keenancrane

http://thenumb.at/Exponential-Rotations/

My son saw the test model there "Spot the cow", and we just had to one and color it in :)

Get yours over at Keenan's model repository:
https://www.cs.cmu.edu/~kmcrane/Projects/ModelRepository/

A photograph of a 3D printed model of Spot the cow. The model was printed using white filament and then coloured (spots and eyes etc were drawn on) with markers.

kevinmoerman, to opensource
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So satisfying to finally reach 100% code coverage for testing!

Hoping to publish paper on Comodo by the end of the year. If you are into help to contribute to Comodo.jl and FEBio.jl and you'll be one of the authors!

https://github.com/COMODO-research/Comodo.jl

A screenshot of a GitHub README showing GitHub badges which includes a badge for "code coverage" by testing. This code coverage badge, showing 100% coverage, is pulsating in this animation to draw attention to it.

kevinmoerman, to random
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My university dropped the campus wide MATLAB license around August last year. It is amusing to see the effect on my GitHub contribution chart. But then I picked up and now there is more than a recovery :)

kevinmoerman,
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@GhostOnTheHalfShell I currently use VScode.

kevinmoerman, to Wikipedia
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If you need a positive background sound, listen to this:

http://listen.hatnote.com/

It is, the sound of people adding free knowledge to the public domain (Wikipedia edits).

I like it because it is a reminder that at any time, somewhere on earth, bit by bit, there is always somebody trying to improve human knowledge.

kevinmoerman, to random
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Implementing "Dijkstra's algorithm" or "mesh distance marching". Computes the on-surface dist from one point to all others (i.e. like a heat spreading across the mesh).
From a seed point, we could add the furthest point to the list and reiterate, compute dist, find furthest point, add this point to list, repeat... This will produce an (approximately) equidistant or geodesic set of points. Handy for remeshing, but it does look like David's got the measles.

https://en.wikipedia.org/wiki/Dijkstra's_algorithm

The animation shows a 3D model (bust of Michelangelo's David), with a sparse set of 100 black dots on the surface of the mesh. These were found using distance marching via Dijkstra's algorithm. The mesh is colored towards the distance to these points. Hence David looks rather speckled/sick.

kevinmoerman, to random
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STL files give each triangle their own coordinates set. So none of the triangles actually share nodes. So step one, after importing such a mesh, is to merge the nodes. This animation shows vertex normal based "inflation", the left is unmerged, the right is merged.

An animation showing mesh inflation for an unmerged mesh and a merged mesh. The triangles separate for the unmerged mesh, making it look like the mesh explodes. For the merged node mesh it looks more like balloon inflation as triangles remain connected.

kevinmoerman,
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@chrishuck yes! It does this for each face:

facet normal ni nj nk
outer loop
vertex v1x v1y v1z
vertex v2x v2y v2z
vertex v3x v3y v3z
endloop
endfacet

Where the v bits are not indices, like any respectable mesh format, but really this triangle's corner coordinates. Hence the nickname "stupid triangle list" :).

The human readable ASCII type files quickly get very big. Hence they invented the binary file version to reduce size, but this issue remains.

kevinmoerman, (edited )
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@chrishuck and when I say it "does this" I mean it has exactly this "code style text" for each face, also horrible! My favorite human readable mesh format is OBJ. It simply has this type of thing for each vertex:
v 0.123 0.234 0.345

Followed by this for each face:
f 1 2 3

The more complex version allows you to add texture and normal directions, and thus indices for those e.g. like:
f 6/4/1 3/5/3 7/6/5

kevinmoerman, to random
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A fun "chain mail"-like weave. Based on the triangulation of the dual (red ) of a triangulation (blue, original triangulation is obtained if you merge the adjacent triangle edges together).

kevinmoerman, to random
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The Cairo pentagonal tiling (red, https://en.wikipedia.org/wiki/Cairo_pentagonal_tiling) is dual to the "snub square" tiling (blue/green, https://en.wikipedia.org/wiki/Snub_square_tiling).

video/mp4

kevinmoerman, to random
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kevinmoerman,
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@ngons with the right parameters perhaps the black can be made the same?

kevinmoerman, to random
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Just read about "rabbit functions", a term for math expressions that are essentially "pulled out of a hat"! Love it, and have to use this in a paper some day.

From "Wachspress 1975, A Rational Finite Element Basis:

"A "rabbit function" is a function that is pulled out of a hat. When a magician pulls a rabbit out of a hat, the effect astonishes the onlookers. Once the illusion is revealed, the rabbit generation is
no more surprising than the generation of rabbits by rabbits."

kevinmoerman, to random
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New : "Experimental and Computational Analysis of Energy Absorption Characteristics of Three Biomimetic Lattice Structures Under Compression" https://arxiv.org/abs/2308.14452

kevinmoerman, to 3DPrinting
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Had some old oddly sticky/oily USB keys, like the plastic on the outside had "gone off", so I decided to design and them a new jacket :)

kevinmoerman, to opensource
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Introducing SolidiPy, a simple code to convert Minecraft-pi builds to STL files for .

This is my first attempt at some , it would be great to get folks to contribute/give feedback.

https://github.com/Kevin-Mattheus-Moerman/solidipy

petersuber, (edited ) to random
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I just released Methods of Rights Retention, an Google doc.
https://bit.ly/MethodsRightsRetention

I wrote it in May and held it for a while to think about what to do with it, for example, move it to my blog or submit it as an article somewhere. But for now I think I'll just release it in this form and consider next steps later.

I hope it's useful. I'd welcome methods, examples, links, or details I might have overlooked.

kevinmoerman,
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@petersuber Cool. Check this out @hardyschwamm

stephenfry, to random

I was stunned when I learned the story of Willem and Frieda, and I hope you’ll manage to catch this film. 2nd March

video/mp4

kevinmoerman,
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@stephenfry As a Dutch person I had never heard of them. Thanks for making this powerful and important documentary!

Sharing the YouTube link for others landing here: https://youtu.be/drq4TYW9gpM?si=4hRBU9ZgJlnhvhBh

kevinmoerman, to opensource
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The Journal of Open Source Software (JOSS) is looking for editors! If you are keen to help this exciting journal check this link and fill out the form:
https://blog.joss.theoj.org/2022/12/call-for-editors

Let me know if you have questions about the journal too.

https://joss.theoj.org

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