[Hugo]

Ok then shell element makes really sense.
Can you poke me again mid-December when I’ll get back from holidays to ask about this plugin?

Best

Hugo

[Hugo]

OK
Just a last question to know what level of accuracy would be needed: which surgery / procedure would you like to model?

Hugo

[Hugo]

You are very welcome @nicklj
Let us know whether you need more guidance.
If it solves your problem, feel free to close this topic.

Best,

Hugo

[Hugo]

Hi @jangirrishabh

Sorry for not getting back to you earlier. But the SOFA Week kept us busy (with many scientific presentations and technical discussions) and I am current out from the office.

There have been discussions on update. A summary will be made available on the “RoadMap” page on sofa-framework.org. Shortly, a new working project is starting on this to unify and improve the data dependency and update. But it will take a bit of time.

Going for the implementation based on what was done in the PR will be useful for the future as well, your contribution is therefore most welcome. Let us know if you face issues or need guidance. But don’t hesitate to PR and we would guide you afterwards if needed.

Best !

Hugo

[Hugo]

About Paraview, I just meant that you can visualize 3D volumetric meshes with it.
Paraview can do it, with crop options (like SOFA) and others.

Next time we met, we can have a Paraview tour together but I am no huge expert of the latest versions.

Best

Hugo

[Hugo]

Just two short remarks

PS: note that using UncoupledConstraintCorrection strongly simplifies your finger model in the constraint resolution.
PS2: note that the time step has (as always) a strong importance in the stability of your simulation

[Hugo]

Dear @nicklj

Thank you for your super enthusiastic reply! The SOFA week is actually the success of the entire community, from PhDs, researchers to industrial partners. We are glad to see the community growing and increasing its simulation activities. It would definitely be a pleasure to get further contributions and to have you with us next year.

Regarding soft robotics, a tutorial should be organized for Robosoft 2020, let me know if you are interested.

For you questions, firt of all, thanks they were clearly identified in your files.
Secondly, sorry for the delayed reply, I am currently in holidays and it took me some time to get your files with the WiFi.

1. Question on Collision: you are right, adding the Line and TriangleCollisionModel do not improve much the simulation. The collision between the points of the fingers and the triangles of the apple seem to be sufficient.

2. OK I better understand which forces you want to extract and how to do it. You are solving the contact using the Lagrange Mutlipliers method described here. It is possible to recover the forces (lambda) resulting from the contact resolution. This is described in the following post.
Let me know if it needs further clarification.

Anyway, nice work! Looking forward to seeing what you will achieve with it!
Best wishes,

Hugo

[Hugo]

Hi @noura

As you know, we usually use Paraview.
If it doesn’t work in SOFA I like to use the TetrahedronSetGeometryAlgorithms: by hiding the VisualModels, you can then set drawTetrahedra=”1″ and set the scaling to drawScaleTetrahedra=”0.8″ this is not bad.
Finally, for advanced render, I would go for Blender ..

I hope this helps
Cheers,

Hugo

[Hugo]

Hi @ma1991

I am sure SOFA can be your holly grall!
I guess you don’t want to limit to the simulation of one yarn, right? you would like to have several yarns interacting, colliding etc. right ?
A volumetric modeling as the one in your video is fine for one yarn but it will quickly become too computationally demanding. Unless you use some numerical optims, like a BeamModel (see BeamFEM) or with model order reduction.
https://github.com/sofa-framework/sofa/blob/master/modules/SofaGeneralSimpleFem/BeamFEMForceField.inl
https://project.inria.fr/modelorderreduction/
Note that recently a plugin implementing the Cosserat model has been released. This formulation could nicely fit your needs as well.
https://github.com/SofaDefrost/plugin.Cosserat

Best

Hugo

[Hugo]

When research from France assist research from Colombia!
Cool to see, thanks @ant0nin, I had not even the time to reply.

Best

Hugo

[Hugo]

Hi @outtt

It is a private plugin belonging to a research team. I don’t know the plugin myself but I can gather information if needed. Then, the discussion would be pursued per email for academic or commercial licensing if it fits your needs.

However, I think before triggering this administrative step, it would be good to understand in which purpose you are modeling the blood vessels: what kind of effort / forces would you like to apply to your vessels?

Depending on this, we could choose the best numerical strategy.
Best wishes,

Hugo

[Hugo]

If my previous reply answers your question, do not hesitate to close this topic.
You can open a new one anytime.

Best wishes,

Hugo

[Hugo]

Hi @charles,

I see you are still digging in the papers.
The collision in SOFA works in three steps: broad detection check (using coarse BVH), narrow detection (several options here, by default using discrete intersection) and response.
In the paper we are following this process with:
– broad phase using BVH
– narrow phase using discrete geometries
– Lagrange multipliers resolution of the contacts (as constraints) including friction.

One of the perpective of the paper is the last option you mentioned: precomputing information for the collision (BVH or other). This was not implemented for the paper. If I remember properly a distance map was finally precomputed and used for the endocardium.

Does this answer your question?
Best,

Hugo

[Hugo]

Dear @nicklj

I am really sorry for the delay of my reply, we have been busy with the SOFA Week. You can find out more about this annual community event on SofaFramework’s YouTube account.

I don’t whether you can share a (simplified) version of your rigid object grasping a deformable one. It would help knowing which collision detection you are using, which resolution/response your are using.

I understood that you are interesting in recovering the force applied on the rigid grasper. Is this correct?

When you say the “force” data field provides extremely large values, how much is this? what are your units?

Sorry for coming up with more questions than answers (for now!).
Best wishes,

Hugo

[Hugo]

Hi @outtt

All beam approaches can not be deformed radially since it is actually the definition of the method: one direction (length) is significantly greater than the two other ones (section).
In the community, vessels are usually represented by beams because the added stiffness due to their presence is of interest. They are also sometimes modeled as static triangulated surfaces when we talk about endovascular catheter navigation.
A third model could be possible is the shell model. I know a private plugin with such an implementation exists.

I hope this helps.
Best,

Hugo

[Hugo]

Hi @eyadshak

Let me notice @faichele for you since he’s the author of this ROS connector. I hope he will be able to assist you.
Best wishes,

Hugo

[Hugo]

Hi @jjcasmar

I agree with you that default integration schemes do not involve Newton steps. It is a pitty. However, the VariationalSymplecticSolver or the StaticSolver are doing it.

Best

Hugo

[Hugo]

Ola @jjcasmar

Good to have you back on the forum!
In SOFA MultiMapping does exist. Do you want to implement your own mapping or using an existing one? Could you provide us a bit more insight on what are your “states” that you want to map?

See examples in examples/Components/mapping/IdentityMultiMapping.scn or SubsetMultiMapping.scn

Cheers,

Hugo

[Hugo]

Dear @nguyenvanpho

Welcome on the SOFA forum!
Have you carefully read the doc on the Linux compilation of SOFA? Especially on this Qt paragraph.

Is the configuration stage finding Qt5 properly?

Best

Hugo

[Hugo]

Hi @djoumessirenethierry

Sorry for the delay of my reply, we have been busy with the SOFA Week. You can find out more about this annual community event on SofaFramework’s YouTube account.

Topological changes are a very hot topic currently.
Independent developers of the community are working on it. API for 2D/3D topological change is working, as well as associated mappings. However, the interaction and (most importantly) the computation of the cut trajectory+remeshing is ongoing.
It is time consuming, but support is welcome on this topic !

You can already see some examples in the folder examples/Components/topology/TopologicalModiers/

Best

Hugo

[Hugo]

Hi @priya-vada4

First of all, welcome in our open source and free forum!
From what I understand you downloaded the sources of SOFA and you compiled it. Right? Did the compilation process run properly?

Best

Hugo

[Hugo]

Dear @bkoo

First of all, I apologize for the delay of my reply. We have been busy with the SOFA Week. You can find out more about this annual community event on SofaFramework’s YouTube account.

I see the problem, but before giving a complete answer could you please explain what you want to do from the position of these points ? do you really need to visualize these tracked spheres?

Best,

Hugo

[Hugo]

Hi guys any update on this topic ?

@epernod @rgao16sofa

Cheers

Hugo

[Hugo]

Any update @suhas1998 @qzha862
Still facing the issue ?
Are you properly using the v19.06 version of SOFA ?

Best

Hugo

[Hugo]

Hi @pguillon

Sorry for the delay of my reply, we have been busy with the SOFA Week. You can find out more about this annual community event on SofaFramework’s YouTube account.

To assist you in defining a proper collision model, having your complete scene or a simplified version of it would help. There is several examples in SOFA but it depends on the method you want to use:
– for the detection : discrete intersection, distance maps.
– for the resolution : penalty method, or Lagrange multiplier resolution
Documentation is available on this online:
Projective Constraint
Lagrange Constraint

Best,

Hugo

[Author]

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