1 Registration algorithm based on image matching for outdoor AR system with fixed viewing position IEE Proc.-Vis. Image Signal Process., Vol. 153, No. 1, February 2006 Speaker ： Po-Hung Lai Date ： 2010/4/13

2 Outline Introduction Principle Architecture of outdoor AR system Experiments Conclusions

3 Introduction Augmented reality –characteristic joints virtual object with realistic environments look like a real part of the scene –example visual medical surgery digital reconstruction of historic sites military industry

4 Introduction –registration three steps positioning rendering merging –key problem is image registration direction-tracking equipment computer vision hybrid registration

5 Introduction –other problem ： placement of markers very sensitive to outdoor lighting randomly hidden from view place markers in many outdoor applications –improvement a fixed-viewing-position outdoor AR system

6 Introduction fixed-viewing-position outdoor AR system –Fourier–Mellin-based –Requires a set of prestored reference images –more accurate and robust

7 Principle 2.1 a fixed-viewing -position outdoor AR system –pin-hole model

8 Principle –camera –Registration problem translation, rotation, scale changes

9 Principle Phase correlation technique for detection of translation –Let and are two images –, are the corresponding Fourier transforms

10 Principle –cross-spectrum of and –inverse Fourier transform of R

11 Principle Phase correlation technique for detection of translation and rotation –According to the property of a Fourier transformation

12 Principle –Fourier –Mellin transform and detection of scale, rotation, and translation (R, S, T): –Fourier transforms and are related

13 Principle –Let and denote the magnitude spectra –Let and denote the transforms of and converted

14 Principle –log transform for in the polar coordinates –Let and denote the corresponding transform of and

15 Principle –Fourier transform of a log-polar map equivalent Fourier–Mellin transform

16 Principle

17 Architecture of outdoor AR system

18 Architecture of outdoor AR system with the Fourier–Mellin transform algorithm –accurate orientation –6 degrees of freedom of camera –joints virtual object with realistic environments

19 Architecture of outdoor AR system

20 Experiments

21 Conclusions difficult 3-D image registration can be simplified to a 2-D image registration intrusive object is not significant, registration result is also correct algorithm cannot be performed in real time on a computer