1. Micro Phase Shifting 2014-07-01 Se-Hoon, Park -Mohit Gupta and Shree K. Nayar, CVPR2012

2. 2 Real-Time Compressive Tracking Contents Phase shifting Phase shift encoding Phase shift decoding Issue Inter reflection Micro Phase shifting Disambiguation experiments

3. Phase shifting  Phase shift encoding Three image structured light I1(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) - 2π/3] I2(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y)] I3(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) + 2π/3] I1(x,y) : first imageI2(x,y) : seond imageI3(x,y) : third image I’(x,y) : average intensityI’’(x,y) : intensity modulationθ(x,y) : phase

4. Phase shifting  Phase shift encoding Ex) I’(x,y) = 125 I’’(x,y) = 125 I1(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) - 2π/3] I2(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y)] I3(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) + 2π/3] θ(x,y)I1(x,y)I2(x,y)I3(x,y) π/6 12523316 π/3 187 0 π/2 23312516 2π/3 25062 5π/6 23316125 π 1870

5.  Phase shift encoding Phase shifting 55 I1I2I3

6. Phase shifting I1(x,y)I2(x,y)I3(x,y)θ(x,y) 12523316 π/6 187 0 π/3 23312516 π/2 25062 2π/3 23316125 5π/6 1870 π

7. Phase shifting  Phase shift decoding Camera image Projector image

8.  Phase shift decoding –If the noise is same in the three camera images, noise doesn’t matter. Phase shifting 8

9. 9 pixel pixel θ (π) θ (π) Input phase output phase ambiguous I1(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) - 2π/3] I2(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y)] I3(x,y) = I’(x,y) + I’’(x,y)cos[θ(x,y) + 2π/3] Input phase Output phase

10. Phase shifting 10 frequency (  ) amplitude Broad Frequency Band  max  mean  min Unambiguous but Noisy Accurate but Ambiguous

11.  Inter reflection Issue 11 camera projector Inter reflections P Q R time Inter reflections Direct Radiance radiance scene

12.  Inter reflection Issue 12 camera projector Inter reflections P Q R time Inter reflections Direct Radiance radiance scene Phase Error

13.  Inter reflection Issue 13 camera projector Inter reflections P Q R scene Inter reflection Illumination pattern light transport coefficients

14.  Inter reflection Issue 14 camera projector Inter reflections P Q R scene Inter reflection Illumination pattern light transport coefficients

15.  Inter reflection Issue 15 camera projector Inter reflections P Q R scene Inter reflection Illumination pattern light transport coefficients

16.  Inter reflection Issue 16 camera projector Inter reflections P Q R scene Inter reflection Illumination pattern light transport coefficients N

17.  Inter reflection Issue 17 Inter reflection * illumination patternlight transport coefficients pixels

18.  Inter reflection Issue 18 frequency projected patterns Inter reflection illumination patternlight transport coefficients

19.  Inter reflection Issue 19 frequency projected patterns Inter reflection illumination patternlight transport coefficients Micro phase shifting

20. Micro Phase shifting 20  max  mean  min frequency (  ) amplitude How Can We Disambiguate Phase Without Low Frequency Patterns?

21. Micro Phase shifting 21 number of periods (unknown)  Phase disambiguation

22. Micro Phase shifting 22 unknownknownunknownknownunknownknown

23. Micro Phase shifting 23

24. Micro Phase shifting 24  Experiments –Ceramic bowl

25. Micro Phase shifting 25  Experiments –Ceramic bowl point projector

26. Micro Phase shifting 26  Experiments –Ceramic bowl Conventional Phase Shifting Micro Phase Shifting [Our]

27. Micro Phase shifting 27  Experiments –Lemon point projector subsurface scacttering

28.  Experiments –Lemon Micro Phase shifting 28 Conventional Phase Sh ifting Micro Phase Shifting [Our]

29.  Experiments –Shiny Metal Bowl Micro Phase shifting 29

30.  Experiments –Shiny Metal Bowl Micro Phase shifting 30 Conventional Phase Shi fting Micro Phase Shifting [Our]