virtual arm for the phantom limb pain therapy
DESCRIPTION
Virtual arm for the Phantom Limb Pain Therapy. Eynard L. and Meyer A. and Bouakaz S. The Phantom Pain. Pain or discomfort felt by an amputee in the area of the missing limb Why? Physical Amputation ≠ Psychic amputation Mismatching between brain and reality → Pain Characteristics - PowerPoint PPT PresentationTRANSCRIPT
UMR 5205
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Virtual arm for the Phantom Limb Pain Therapy
Eynard L. and Meyer A. and Bouakaz S.
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The Phantom Pain
Pain or discomfort felt by an amputee in the area of the missing limb
Why? Physical Amputation ≠ Psychic amputation Mismatching between brain and reality → Pain
CharacteristicsStrong pain, sometimes debilitatingHard to treat
Existing therapiesMedics, massage, relaxation, psychotherapiesNew hopeful therapies …
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News methods for therapy
[Ramachadran96] Cognitive Science Institute ISC Lyon [Sirigu03]
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Our idea
Computer Science Posture Tracking (vision) Augmented reality: virtual limb
Our system Camera Posture analysis Augmented picture of missing limb Mirror screen
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Presentation summary
Previous Works
Our contributionReal-Time Posture AnalysisThe mirror effect : Virtual arm
Results
Conclusion
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Movements Tracking (vision)
Multi-camerasVoxelic reconstruction [Mikic03,…] 3D-model : recognition of the skeleton a 3d-grid
Monocular (1 camera)Optical flow Bayesian methods [Agarwal04,…]Real-Time [Stenger03,…]
Limited movementSmall resolution
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Our system constraints
Ours constraints Real-Time (Interactivity) Monocular (portative system)
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Presentation summary
Previous Works
Our contributionReal-Time Posture Analysis
Background substraction Precomputation: anthropometric measures Posture Tracking
Mirror effect : Virtual arm
Results
Conclusion
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Background substraction
Learning-based algorithm N frames → RGB values extrema for each pixel Connexity search → noise reduction
Simple and fast
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Precomputation: anthropometric measures
Anthropometric values computation Needed for the tracking
2 postures
Silhouette extraction
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Head and Torso measurements
Pose 1: head measure Highest pixel in silhouette
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Head and Torso measurements
Pose 1: head measure Highest pixel in silhouette Going down into the image while Nbi(whitepixel)> Nbi-1(whitepixel)
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Head and Torso measurements
Pose 1: head measure« highest » pixel in frameGoing down on the image while Nbi(whitepixel)>Nbi-1(whitepixel)
→ Head widthGoing down until Nb(whitepixel) < threshold* width
→ Shoulder line
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Head and torso measurements
Torso measure Barycenter line → Torso width Going down until separation → bottom of the torso
→ Torso height
widthheight
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Arm measurements
Pose 1Level and side of the amputation
Each arms sizes
Horizontal extreme points
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Arm measurements (2)
Pose 2
lbrachium
H
h /2elbow
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Presentation summary
Previous Works
Our contributionReal-Time Posture Analysis
Background substraction Precomputation: anthropometric measures Posture Tracking
Mirror effect : Virtual arm
Results
Conclusion
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Head and Torso detection
Head and TorsoConnexity research algorithm helped by the
anthropometrics measures
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Seek articulations
Seeking shoulder, elbow and wrist
Anthropometrics measurements → estimation of the positions
S
Sv
v~
E~
E
Forearmaxis
P1P2
C1
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Missing limb creation
If before-elbow amputationCoordinates systems of valid and amputee side are equivalentReprojection of pixels valid side → amputee side
Sv S
a
Xs
Ys
Xa
Ya
A s
A a
copy
Ov
Oa
Ev
W
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Virtual arm creation
If below-elbow amputationCoordinates system of valid and amputee side are equivalentReprojection of pixels valid side → amputee side
Sv S
a
XsYs
a
Ya
A s
Aa
copy
Ov
Oa
Ev
W
Ea
X
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Results
Webcam (640*480)
About 8 to 10 frames / s
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Remarks
Up Follow-up the side-displacements of the silhouette Whole image reflecting Better illusion for subject Interactive time
ConstrainsSubject must be facing the cameraFor a better illusion the elbows angles have to be
symmetricNon Snake moves
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Conclusion and future works
Experimental systemSimple posture trackingConstrains but robustVirtual arm creation
Next stepExperiment on amputeeCollaboration with ISC of Lyon
Perspectives 3D-model to be more realistic Amputees reactions to real experiments
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Thank you …
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Ajout du membre → réalité augmentée (RA)
Problème générique en RA
Cohérence entre réel et virtuel Texture, aspect
Élément de synthèse construit à partir d’image réelle (cf notre système)
Illumination, Ombre
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Creation du membre manquant
amputation huméralecentre de gravité du moignon obtention d'un axe grâce a al même méthode que pour le
bras valideamputation cubitaleMême méthode que pour le bras valideObtention de l'axe du moignon grâce au centre de gravité
de la partie après le coude
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hhead
htorsolLarm
whead
w
lRarm
yneck
ypelvis
xmin
xmax
xRshoulder
xLshoulder
torso
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