[SOLVED] Applying Self collision

[BEK]

Hi, everyone. I am the new user of SOFA.

I’m interest in knot tying in medical surgery
I tried to make knot model using two method.

One knot consist of points and each point was linked by MeshspringForceField and LineBendingSprings. About collision model, Sphere and Line model were applied.
I found selfCollision properties of both collision models, so I applied too.

I could tie this knot but it didn’t tie up tightly.
I guess light(?) self-collision and its adaptation process is needed to knot tying.

Same problem was happened on the other model
I made knot using mesh models (for realistic… ) but it also has selfcollision problem.
How can I solve this problem?

Thank you.

[Hugo]

Dear @eunkyungbae,

Simulation of suture or knot tying is currently a topic of research. Several groups are starting to focus on this topic. If you are interested, I could invite you to future discussions about it.

To answer your question: yes to have a realistic knot simulation, you need self-collision.
Could you share an example scene with us so that we can better understand and help you?

Best

Hugo

[BEK]

Dear @Hugo
Sorry to late reply.
I tried to asscess c++ code to control self-collision, but I don’t knot how to change or add.

This is my thread model I used.
model(PointLine50.obj) only consist of point and line.
I tag on point collision model for control by other tool.

<Node name=”springthread”>
 <Gravity name=”R_Gravity” gravity=”0 0 0″ />
 <EulerImplicitSolver rayleighStiffness=”0.01″ rayleighMass=”0.01″ />
 <CGLinearSolver template=”GraphScattered” iterations=”20″ threshold=”1e-008″ tolerance=”1e-5″ />
 <MeshTopology name=”Mesh” fileTopology=”PointLine50.obj” />
 <MechanicalObject template=”Vec3d” name=”DOFs” scale3d=”1 1 1″ restScale=”1″ src=”@Mesh” translation=”-1 -5.0 -2.0″ rotation=”320 0 0″ scale=”2 2 2″/>
 <UniformMass mass=”1″ />
 <FixedConstraint template=”Vec3d” name=”default6″ indices=”0″ />

<MeshSpringForceField name=”Springs” stiffness=”100000″ damping=”0″ />
 <LineBendingSprings name=”BS” stiffness=”10000″ damping=”0″ />

<UncoupledConstraintCorrection />
 <Point tags=”tip_thread_col” />
 <Line selfCollision=”0″ contactStiffness=”10000″/>

<Node name=”Collision”>
 <EdgeSetTopologyContainer />
 <EdgeSetTopologyModifier />
 <MechanicalObject template=”Vec3d” name=”splineMapped” />
 <CatmullRomSplineMapping input=”@../DOFs” output=”@splineMapped” SplittingLevel=”1″ />
 <Node name=”Visu”>
 <OglModel template=”ExtVec3f” name=”VisualModel” src=”@../” lineWidth=”6″ lineSmooth=”1″/>
 <OglTexture id=”imageTex” textureFilename=”textures/textureorange3569.png” textureUnit=”0″ repeat=”1″ />
 <IdentityMapping input=”@..” output=”@VisualModel” />
 </Node>
 </Node>
 </Node> 

[Hugo]

Hi Bek,

could you please share the mesh/data with us ?
this would help to test,

cheers,

Hugo

[BEK]

Dear @Hugo
I uploaded my model obj
down

[Hugo]

Hi @eunkyungbae

I fixed it.
The problem was the quote you were using and I changed the MeshTopology into : one MeshObjLoader and one Mesh component.

Scene below:

<Node name="springthread">
    <VisualStyle displayFlags="showCollisionModels showVisual" />

	<Gravity name="R_Gravity" gravity="0 0 0" />
	<MeshObjLoader name="Mesh" filename="PointLine50.obj" />
	<Mesh src="@Mesh" />
	<EulerImplicitSolver rayleighStiffness="0.01" rayleighMass="0.01" />
	<CGLinearSolver template="GraphScattered" iterations="20" threshold="1e-008" tolerance="1e-5" />
	<MechanicalObject template="Vec3d" name="DOFs" scale3d="1 1 1" restScale="1" src="@Mesh" translation="-1 -5.0 -2.0" rotation="320 0 0" scale="2 2 2"/>
	<UniformMass mass="1" />
	<FixedConstraint template="Vec3d" name="default6" indices="0" />

	<MeshSpringForceField name="Springs" stiffness="100000" damping="0" />
	<LineBendingSprings name="BS" stiffness="10000" damping="0" />

	<UncoupledConstraintCorrection />
	<Point tags="tip_thread_col" />
	<Line selfCollision="0" contactStiffness="10000"/>

	<Node name="Collision">
		<EdgeSetTopologyContainer />
		<EdgeSetTopologyModifier />
		<MechanicalObject template="Vec3d" name="splineMapped" />
		<CatmullRomSplineMapping input="@../DOFs" output="@splineMapped" SplittingLevel="1" />
		<Node name="Visu">
			<OglModel template="ExtVec3f" name="VisualModel" src="@../" lineWidth="6" lineSmooth="1"/>
			<OglTexture id="imageTex" textureFilename="textures/textureorange3569.png" textureUnit="0" repeat="1" />
			<IdentityMapping input="@.." output="@VisualModel" />
		</Node>
	</Node>
</Node>

Let me know if this is what you need.
Cheers,

Hugo

[Wong]

Hello @hugo,

Has the simulation of suture and knot tying been done now?
If done, and possible, I can pay for it to use the plugin. Otherwise, I can take part in the discussion and help develop.

Thanks
Wong

[Hugo]

Dear @outtt

There is no ready-to-use plugin for knot tying at my best knowledge. It has been investigated but nothing has come up yet.
Maybe @eunkyungbae has some update about her work?

I will close this topic, but do not hesitate a new topic for any further question!
Best,

Hugo

[Wong]

Hello @hugo,

And what about suture? I want to know how it is going.

Wong

[Author]

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