Geomagic Plugin collision model and reference models #4232

oystebje · 2023-10-11T14:45:46Z

oystebje
Oct 11, 2023

Hello,

I'm playing around with changing out the collision model in the Geomagic haptics plugin, as implemented in the "Geomagic-FEMLiver.scn" example. The purpose is to get custom instrument representations, and to improve collision detection (sometimes the line collision model goes through the deformable object mesh). Code sample below.

From the Liver example, I would expect there to be a visual model, and a collision model. However, there are these two reference models in addition - "refModelRight" and "refModelLeft", and I'm having a hard time wrapping my head around what these actually do. Does anybody know why they are needed?

Best,
Øystein

#OMNI NODE BEGIN****
    omni = rootNode.addChild('Omni')
    omni.addObject('MechanicalObject', name='DOFs', template='Rigid3d', position='@GeomagicDevice.positionDevice')
    omni.addObject('MechanicalStateController', template="Rigid3d", listening="true", mainDirection="1 0 0", handleEventTriggersUpdate="true")

    visuAvatar = omni.addChild('visuAvatar', activated="false")
    visuAvatar.addObject('MeshOBJLoader', name="meshLoader_0", filename="mesh/sphere.obj", scale="0.1", handleSeams="1")
    visuAvatar.addObject('OglModel', name="Visual", src="@meshLoader_0", color="gray")
    visuAvatar.addObject('RigidMapping', input="@..", output="@Visual", index="0") 

    refModel = omni.addChild('refModel')
    refModel.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    refModel.addObject('MeshTopology', src="@loader")
    refModel.addObject('MechanicalObject', src="@loader", name="instrumentRefState1", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    refModel.addObject('RigidMapping')

    refModelRight = omni.addChild('refModelRight')
    refModelRight.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    refModelRight.addObject('MeshTopology', src="@loader")
    refModelRight.addObject('MechanicalObject', src="@loader", name="instrumentRefState2", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    refModelRight.addObject('RigidMapping')

    refModelLeft = omni.addChild('refModelLeft')
    refModelLeft.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    refModelLeft.addObject('MeshTopology', src="@loader")
    refModelLeft.addObject('MechanicalObject', src="@loader", name="instrumentRefState3", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    refModelLeft.addObject('RigidMapping')
    #OMNI NODE END****



    #INSTRUMENT NODE BEGIN****
    geomagic = rootNode.addChild('Instrument')
    geomagic.addObject('EulerImplicitSolver', name="ODE solver", rayleighStiffness="0.05", rayleighMass="1.0")
    geomagic.addObject('CGLinearSolver', name="linear solver", iterations="25", tolerance="1.0e-10", threshold="10.0e-10")
    geomagic.addObject('MechanicalObject', name='instrumentState', template='Rigid3d')#, position="-3 -3 -3 0 0 0 1")
    geomagic.addObject('UniformMass', name="mass", totalMass="0.5")
    geomagic.addObject('LCPForceFeedback', activate="true", forceCoef="0.1")
    geomagic.addObject('UncoupledConstraintCorrection')
    
    #Instrument visual model
    instrumentVisu = geomagic.addChild('InstrumentVisualModel')
    instrumentVisu.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument.obj", handleSeams="1")
    instrumentVisu.addObject('OglModel', name="InstrumentVisualmodel", src="@loader", color="1.0 0.2 0.2 1.0", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    instrumentVisu.addObject('RigidMapping', name="MM->VM mapping", input="@instrumentState", output="@InstrumentVisualModel") 
    
    #Instrument collision model
    instrumentCollision = geomagic.addChild('instrumentCollision')
    instrumentCollision.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    instrumentCollision.addObject('MeshTopology', src="@loader")
    instrumentCollision.addObject('MechanicalObject', name="instrumentCollisionState1", src="@loader", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    instrumentCollision.addObject('LineCollisionModel', contactStiffness="10")
    instrumentCollision.addObject('PointCollisionModel', contactStiffness="10")
    instrumentCollision.addObject('RigidMapping', name="MM->CM mapping", input="@instrumentState", output="@instrumentCollisionState1")

    #Instrument RefModelRight
    refModelRight = geomagic.addChild('refModelRight')
    refModelRight.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    refModelRight.addObject('MeshTopology', src="@loader")
    refModelRight.addObject('MechanicalObject', name="instrumentCollisionState2", src="@loader", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    refModelRight.addObject('RigidMapping', name="MM->CM mapping", input="@instrumentState", output="@instrumentCollisionState2")
    
    #Instrument RefModelLeft
    refModelLeft = geomagic.addChild('refModelLeft')
    refModelLeft.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
    refModelLeft.addObject('MeshTopology', src="@loader")
    refModelLeft.addObject('MechanicalObject', name="instrumentCollisionState3", src="@loader", ry="-180", rz="-90", dz="3.5", dx="-0.3")
    refModelLeft.addObject('RigidMapping', name="MM->CM mapping", input="@instrumentState", output="@instrumentCollisionState3")
    
    #Vector spring force field
    geomagic.addObject('VectorSpringForceField', template="Vec3d", object1="@Omni/refModel/instrumentRefState1", object2="@Instrument/instrumentCollision/instrumentCollisionState1", stiffness="10", viscosity="0")
    geomagic.addObject('VectorSpringForceField',template="Vec3d", object1="@Omni/refModelRight/instrumentRefState2", object2="@Instrument/refModelRight/instrumentCollisionState2", stiffness="10", viscosity="0")
    geomagic.addObject('VectorSpringForceField',template="Vec3d", object1="@Omni/refModelLeft/instrumentRefState3", object2="@Instrument/refModelLeft/instrumentCollisionState3", stiffness="10", viscosity="0")
    #INSTRUMENT NODE END***

Answered by oystebje

Oct 13, 2023

Okay, so I updated the Geomagic scene using the same structure as suggested with the Force Dimensions plugin (see https://gitlab.com/polyakovkrylo/forcedimensions/-/blob/master/scenes/OmegaInstrumentController.scn?ref_type=heads)

This seems to give more or less the same result but with less code, and runs very well on my computer. And it's easier to understand. I suppose the "RestShapeSpringsForceField" in the code below does the same job as the "VectorSpringForceField" in the code above.

#OMNI NODE BEGIN****
omni = rootNode.addChild('Omni')
omni.addObject('MechanicalObject', name='DOFs', template='Rigid3d', position='@GeomagicDevice.positionDevice')
#OMNI NODE END*****

#INSTRUMENT NODE …

View full answer

bakpaul · 2023-10-11T15:46:51Z

bakpaul
Oct 11, 2023
Maintainer

That is strange. What happens when you remove them ? I suppose nothing apart from the fact that the link between the 'Insutrument' and the 'omni' is less stiff ?

This may come from old tests done with that ? I am not sure, let's see what the others think of it

1 reply

oystebje Oct 13, 2023
Author

@bakpaul nothing happens, really. It still works. Perhaps it is slightly less stiff, but I don't really notice any difference.

oystebje · 2023-10-13T09:18:15Z

oystebje
Oct 13, 2023
Author

Okay, so I updated the Geomagic scene using the same structure as suggested with the Force Dimensions plugin (see https://gitlab.com/polyakovkrylo/forcedimensions/-/blob/master/scenes/OmegaInstrumentController.scn?ref_type=heads)

This seems to give more or less the same result but with less code, and runs very well on my computer. And it's easier to understand. I suppose the "RestShapeSpringsForceField" in the code below does the same job as the "VectorSpringForceField" in the code above.

#OMNI NODE BEGIN****
omni = rootNode.addChild('Omni')
omni.addObject('MechanicalObject', name='DOFs', template='Rigid3d', position='@GeomagicDevice.positionDevice')
#OMNI NODE END*****

#INSTRUMENT NODE BEGIN****
instrument = rootNode.addChild('Instrument')
instrument.addObject('EulerImplicitSolver', name="ODE solver", rayleighStiffness="0.05", rayleighMass="1.0")
instrument.addObject('CGLinearSolver', name="linear solver", iterations="25", tolerance="1.0e-5", threshold="10.0e-5")
instrument.addObject('MechanicalObject', name='instrumentState', template='Rigid3d')
instrument.addObject('UniformMass', name="mass", totalMass="0.1")
instrument.addObject('LCPForceFeedback', activate="true", forceCoef="0.9")
instrument.addObject('UncoupledConstraintCorrection')
instrument.addObject('RestShapeSpringsForceField', stiffness="1000", angularStiffness="1000", external_rest_shape="@/Omni", points="0")
    
#Instrument visual model
instrumentVisu = instrument.addChild('InstrumentVisualModel')
instrumentVisu.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument.obj")
instrumentVisu.addObject('OglModel', name="InstrumentVisualmodel", src="@loader", color="gray", ry="-180", rz="-90", dz="3.5", dx="-0.3")
instrumentVisu.addObject('RigidMapping', name="MM->VM mapping", input="@instrumentState", output="@InstrumentVisualModel") 
    
#Instrument collision model
instrumentCollision = instrument.addChild('instrumentCollision')
instrumentCollision.addObject('MeshOBJLoader', name="loader", filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj")
instrumentCollision.addObject('MeshTopology', src="@loader")
instrumentCollision.addObject('MechanicalObject', name="instrumentCollisionState1", src="@loader", ry="-180", rz="-90", dz="3.5", dx="-0.3")
instrumentCollision.addObject('LineCollisionModel', contactStiffness="10")
instrumentCollision.addObject('PointCollisionModel', contactStiffness="10")
instrumentCollision.addObject('RigidMapping', name="MM->CM mapping", input="@instrumentState", output="@instrumentCollisionState1")
#INSTRUMENT NODE END****

3 replies

epernod Nov 14, 2023
Maintainer

If I'm not wrong the RestShapeSpringFF also apply on the rotation compare to the VectorSpring version
Anyway we need to update the example of FEM-Liver. I think it is confusing to have 3 tools

hugtalbot Dec 8, 2023
Maintainer

+1 @epernod
is your point solved @oystebje ?

oystebje Dec 8, 2023
Author

@hugtalbot I'm happy :-)

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Geomagic Plugin collision model and reference models #4232

oystebje Oct 11, 2023

Replies: 2 comments · 4 replies

bakpaul Oct 11, 2023 Maintainer

oystebje Oct 13, 2023 Author

oystebje Oct 13, 2023 Author

epernod Nov 14, 2023 Maintainer

hugtalbot Dec 8, 2023 Maintainer

oystebje Dec 8, 2023 Author

oystebje
Oct 11, 2023

Replies: 2 comments 4 replies

bakpaul
Oct 11, 2023
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oystebje Oct 13, 2023
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oystebje
Oct 13, 2023
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epernod Nov 14, 2023
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hugtalbot Dec 8, 2023
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oystebje Dec 8, 2023
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