su-ting, chuang 2010/8/2. outline introduction related work system and method experiment conclusion...
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Finger Detection for Multi-Touch Tabletop Display System
多重觸控桌面顯示系統之手指偵測
Su-ting, Chuang2010/8/2
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OutlineIntroductionRelated WorkSystem and MethodExperimentConclusion & Future Work
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OutlineIntroductionRelated WorkSystem and MethodExperimentsConclusion & Future Work
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Introduction
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OutlineIntroductionRelated WorkSystem and MethodExperimentsConclusion & Future Work
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Related WorkFTIR (Frustrated Total Internal Reflection)
J. Y. Han, “Low-cost multi-touch sensing through frustrated total internal reflection," in Proceedings of the 18th annual ACM symposium on User interface software and technology (UIST '05). New York, NY, USA: ACM Press, 2005, pp. 115-118.
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Related WorkDI (Diffused Illumination)
J. Rekimoto and N. Matsushita, “Perceptual surfaces: Towards a human and object sensitive interactive display," Workshop on Perceptural User Interfaces (PUI'97), 1997.
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Related WorkTouchLib
A multi-touch development kit
Finger detection processing flow chart
BackgroundSubtraction
SimpleHighpass Scale Threshold
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OutlineIntroductionRelated WorkSystem and MethodExperimentsConclusion & Future Work
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Hardware Configuration
(2) IR Camera
(3) IR Illuminator
(1) Peripheral Projector
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Hardware ConfigurationOrder of diffuser layer and touch-glass layer
Diffuser layer
IR illuminatorIR camera
spot
IR illuminator
IR camera
Touch-glass layer
IR camera
spot
IR camera
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1
4 3
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Hardware ConfigurationProblem:
IR rays will be reflected by the touch-glass and resulting hot spot regions in camera views
Solution:Use other cameras to recover the regions
which are sheltered by IR spots
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Software ArchitectureDetection system
Image StitchingFinger DetectionFinger Tracking
Parameter determination
ImageStiching
FingerDetection
Finger Tracking
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Software ArchitectureDirectShow
Filter-based framework GShow
GPU-accelerated framework
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Image Stitching
ImageBlending
IR Camera
IR camera
Undistortion
Undistortion
HomoWarp
HomoWarp
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Image StitchingHomoWarp
Goal Unify finger size among different position of table
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Image StitchingHomoWarp
Method Calculate homography in advance
5 2
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2 5
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1
4
3
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VSLH VS
RH
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5
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Image StitchingHomoWarp
Warp image from each camera to virtual space
VSLH
VSRH
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Image StitchingImage Blending
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Parameter DeterminationRequirements of ideal finger detection
systemSensitive Noise-free
Evaluation of parametersData Collection
Depict traceMeasurement
Minimize miss and false alarm
Miss
False Alarm
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Parameter DeterminationIdeal finger detection
Only one fingertip landing on traceContinuity among frames
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Parameter Determination
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Parameter Determination
Parameters Determinator
Parameter Combination
Detection Result
Applicable set of Parameters
TestSet
Touch Data
Ground Truth
(Trace)
Detection System
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OutlineIntroductionRelated WorkSystem and MethodExperimentsConclusion & Future Work
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ExperimentsPerformance evaluation
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ExperimentsParameter determination
Decide parameters in our systemAdopt sampling-based parameter search
technique
Normalization Difference of Gaussian
Background Subtraction Binary Finger
Analysis
Subtract value
Smoothkernel Threshold Finger
Size
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ExperimentsParameter determination
Exhaustive search Parameter combination
5 (step) *5 (step) *5 (step) *5 (step) = 625 Applicable parameter num
16/625 = 2.56%
Subtract value
Smooth kernel Threshold Finger size
Low bound 0 5 10 10
Step 5 5 5 10
High bound 15 17 30 50
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ExperimentsParameter determination
Particle filtering
Sampling
Measure
1 1( | )t tP X Z
1( | )t tP X Z
( | )t tP X Z
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Experiments
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Experiments
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OutlineIntroductionRelated WorkSystem and MethodExperimentsConclusion & Future Work
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