Bad performances using SofaCarving

[carlolodin]

Hi, I'm trying to use SofaCarving to simulate a tissue that should be cut using a robotic gripper.
However, I could manage to implement it only as a fixed object (only contact and visual model), and even this way, the simulation takes way too much time to compute the steps in which the triangles are removed from the mesh.
I would appreciate if anyone could give me a clue in how to solve these two problems.
Here's some of the code from my scene:

root.addObject('FreeMotionAnimationLoop', parallelCollisionDetectionAndFreeMotion="true", parallelODESolving="true")
root.addObject('GenericConstraintSolver', resolutionMethod="false", tolerance="1e-4", maxIterations="250", multithreading="true")
root.addObject('CollisionPipeline', name="CollisionPipeline", verbose="0")
root.addObject('BruteForceBroadPhase', name="BroadPhase")
root.addObject('BVHNarrowPhase', name="NarrowPhase")
root.addObject('LocalMinDistance', name="LMD-proximity" , alarmDistance=0.0015, contactDistance=0.00075, useLMDFilters=0)
root.addObject('DefaultContactManager', name="CollisionResponse", response="FrictionContactConstraint")
root.addObject('CarvingManager', name='CarvingManager', printLog='1', carvingDistance='.001')

[...]

Fat_collision = root.addChild('Fat_collision')
    Fat_collision.addObject('MeshGmshLoader', name='loader', filename='xyz.msh', translation='0.012 -0.014 -.04', scale3d='1000 1000 1000')
    Fat_collision.addObject('MechanicalObject', name="dofs", src="@loader")
    Fat_collision.addObject('TriangleSetTopologyContainer', name='triangles', src='@loader')
    Fat_collision.addObject('TriangleSetGeometryAlgorithms', name='geomAlgo', template='Vec3d')
    Fat_collision.addObject('TriangleSetTopologyModifier', name='trianglesModifier')
    Fat_collision.addObject('TriangleCollisionModel', name='trianglesCollision', group='10', moving='0', simulated='0', bothSide='0', contactStiffness='.01', computeNormals='0', tags='CarvingSurface')
    
    Fat_visual = Fat_collision.addChild('Fat_visual')
    Fat_visual.addObject('OglModel', name="VisualModel", material="Default Diffuse 1 1 0 0 1 Ambient 1 0.2 0 0 1 Specular 0 1 0 0 1 Emissive 0 1 0 0 1 Shininess 0 45", src="@../triangles",color=[1, 1, 0.3])
    Fat_visual.addObject('IdentityMapping', name="VisualMapping", input="@../dofs", output="@VisualModel")

[...]
Right_Jaw_Collision_2 = Gripper2_Parts.addChild('Right_Jaw_Collision_2')
    
    Right_Jaw_Collision_2.addObject('MeshObjLoader', name="meshloader", filename="zyx.obj")
    Right_Jaw_Collision_2.addObject('MeshTopology', src="@meshloader")
    Right_Jaw_Collision_2.addObject('MechanicalObject', name="model", src="@meshloader")
    Right_Jaw_Collision_2.addObject('PointCollisionModel', moving="1", simulated="1", group="1", tags="CarvingTool")
    Right_Jaw_Collision_2.addObject('RigidMapping', input="@..", output="@model", index="1",)

Before this version, I tried to define the tissue like this:

Fat = root.addChild('Fat')
    Fat.addObject('MeshGmshLoader', name='loader', filename='xyz.msh', translation='0.0125 -0.014 -.04')
    Fat.addObject('EulerImplicitSolver', name="odesolver",rayleighStiffness="0.8", rayleighMass="0.01")
    Fat.addObject('SparseLDLSolver', template="CompressedRowSparseMatrix")
    Fat.addObject('MechanicalObject', name="dofs", src="@loader")
    Fat.addObject('TetrahedronSetTopologyContainer', name="topo", src="@loader", createTriangleArray='1')
    Fat.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3d", name="GeomAlgo")
    Fat.addObject('TetrahedronSetTopologyModifier', name="GeomMod", removeIsolated='0')
    Fat.addObject('MeshMatrixMass', name="mass", totalMass= "0.01", showAxisSizeFactor="0.005")
    Fat.addObject('TetrahedralCorotationalFEMForceField',template="Vec3d", youngModulus=100, poissonRatio=0.4, method="large", 
                    computeGlobalMatrix="1", updateStiffnessMatrix="false")
    Fat.addObject('FixedPlaneConstraint', name='constraint')
    
    Fat_collision = Fat.addChild('Fat_collision')
    Fat_collision.addObject('TriangleSetTopologyContainer', name='triangles', src='@loader')
    Fat_collision.addObject('Tetra2TriangleTopologicalMapping', name='tetra2triangle', input='@../topo', output='@triangles')
    Fat_collision.addObject('TriangleSetGeometryAlgorithms', name='geomAlgo', template='Vec3d')
    Fat_collision.addObject('TriangleSetTopologyModifier', name='trianglesModifier')
    Fat_collision.addObject('TriangleCollisionModel', name='trianglesCollision', group='10', tags='CarvingSurface')
    
    Fat_visual = Fat_collision.addChild('Fat_visual')
    Fat_visual.addObject('OglModel', name="VisualModel", material="Default Diffuse 1 1 0 0 1 Ambient 1 0.2 0 0 1 Specular 0 1 0 0 1 Emissive 0 1 0 0 1 Shininess 0 45", src="@../loader",color=[1, 1, 0.3])
    Fat_visual.addObject('IdentityMapping', name="VisualMapping", input="@../../dofs", output="@VisualModel")

However, this way it would correctly modify the collision model but not the visual, which created triangles in random directions.

[hugtalbot]

Hi @carlolodin

My first question would be, how many vertices does your mesh include?
I add in this discussion @rmolazem

[carlolodin]

Hi @hugtalbot, thank you for your reply. The mesh currently has 150 vertices, but I will probably have to replace it with a more detailed one. Is it too many?

[carlolodin]

Updates: I've managed to make it work using MultiThreading for collision detection. Here's the code:

Fat = root.addChild('Fat')
    Fat.addObject('EulerImplicitSolver', rayleighMass='0.1', rayleighStiffness='0.1')
    Fat.addObject('SparseLDLSolver', template="CompressedRowSparseMatrixMat3x3d")
    Fat.addObject('MeshGmshLoader', name="loader", filename="XXX", translation='-.0375 -.015 .04',rotation='-90 0 0', scale='.001')
    Fat.addObject('MechanicalObject', src="@loader", name="Volume")
    Fat.addObject('TetrahedronSetTopologyContainer', src="@loader", name="Container")
    Fat.addObject('TetrahedronSetTopologyModifier', name="Modifier")
    Fat.addObject('TetrahedronSetGeometryAlgorithms', name="GeomAlgo", template="Vec3d")
    Fat.addObject('DiagonalMass', massDensity="0.05")
    Fat.addObject('BoxROI', name='ROI1', box="-.05 -.02 -.1 .05 -.014 .1", doUpdate='0')
    Fat.addObject('FixedConstraint', name='FixedConstraint1', indices="@ROI1.indices")
    Fat.addObject('FastTetrahedralCorotationalForceField', name='CFEM', youngModulus="0.1", poissonRatio="0.4", method="large")
    #Fat.addObject('ParallelTetrahedronFEMForceField', name='CFEM', youngModulus="0.1", poissonRatio="0.4", method="large")
    Fat.addObject('GenericConstraintCorrection', name='Fat_constraint')

    
    FatCollision = Fat.addChild('FatCollision')
    FatCollision.addObject('TriangleSetTopologyContainer', name="Container")
    FatCollision.addObject('TriangleSetTopologyModifier', name="Modifier")
    FatCollision.addObject('TriangleSetGeometryAlgorithms', name="GeomAlgo", template="Vec3d")
    FatCollision.addObject('Tetra2TriangleTopologicalMapping', input="@../Container", output="@Container")
    FatCollision.addObject('TriangleCollisionModel', tags="CarvingSurface")
    
    FatVisual = FatCollision.addChild('FatVisual')
    FatVisual.addObject('OglModel', name="Visual", material="Default Diffuse 1 1 1 0 1 Ambient 0 1 1 1 1 Specular 1 1 1 0 1 Emissive 0 1 1 0 1 Shininess 1 100")
    FatVisual.addObject('IdentityMapping', input="@../../Volume", output="@Visual")

Now, when I interact with the object, the biggest bottleneck seems to be SolveConstraint: POSITION AND VELOCITY - BuildSystem / Get Compliance. In the documentation I've read that one way to improve this step would be to activate parallelInverseProduct in SparseLDLSolver, but I don't have this option (I guess that's because I'm using Sofa v23.06.00). Do you suggest to update Sofa or is there another way to improve this?

[epernod]

hi,

150 points is not too much at all. You could easily go to mesh with thousands points to be carved.
What might slow down your simulation is the collision detection distances. But looking at your scene, alarmDistance=0.0015, contactDistance=0.00075 are very small already.
A way to check what is the problem, could you remove the carvingEngine and just simulate the collision to see if it is already slow or not.

In addition to the exampes provided in the SofaCarving plugin, you could check this repository, there are other carving scene examples.

Best regards

[carlolodin]

Hi, thanks for your help! What would you suggest in general for alarmDistance and collisionDistance values?
Best regards,
Carlo

[epernod]

It really depends on the size of your mesh.
Typically the distance you use in the collision should only include a small set of vertices on the surface.
You can check that by activating the detectionOutput display in runSofa

[github-actions[bot]]

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@carlolodin
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding