Mesostructure from Specularity Using Coded Illumination
Yannick Francken, Tom Mertens, Jo Gielis, Philippe Bekaert Expertise Centre for Digital Media Hasselt University (Belgium) {yannick.francken, tom.mertens, Goal Acquire mesostructures normal map Mesostructure Normal map Previous Work Shape from shading [Horn75, Zhang99] Previous Work Shape from shading [Horn75, Zhang99]
Photometric stereo [Woodham89, Ikeuchi92] Previous Work Shape from shading [Horn75, Zhang99]
Photometric stereo [Woodham89, Ikeuchi92] Structured light [Boyer87, Scharstein03] Previous Work Shape from shading [Horn75, Zhang99]
Photometric stereo [Woodham80, Ikeuchi92] Structured light [Boyer87, Scharstein03] Mesostructure scanning Mesostructure from Specularity [Chen06] Previous Work Shape from shading [Horn75, Zhang99]
Photometric stereo [Woodham80, Ikeuchi92] Structured light [Boyer87, Scharstein03] Mesostructure scanning Mesostructure from Specularity [Chen06] Rapid Acquisition of Specular and Diffuse Normal Maps from Polarized Spherical Gradient Illumination [Ma07] Previous Work Mesostructure from specularity [Chen06] Setup
Image captures Previous Work Mesostructure from specularity [Chen06]
Detecting specularities Law of reflection V = 2(NTL)N - L L V N Observation A specularity is caused by one light source 1011 1100 100
1001 10 1 1101 1010 1001 1110 1000 1111 O(log N) instead of O(N) image captures! Setup Screen-camera setup Binary coded light patterns
Screen as cheap controllable light source [Zongker96, Tarini05, Clark05, Funk06] Calibration [Hartley04, Tarini05, Francken06, Funk06] Binary coded light patterns Gray code M x N light sources log2M + log2N + 1 patterns Results Limits Only specular mesostructures Sharp specular highlights Limits Only specular mesostructures Sharp specular highlights
Limited cone of normals Planar display Limits Only specular mesostructures Sharp specular highlights
Limited cone of normals Planar display Self shadowing Conclusion Efficient Inexpensive setup O(log N) instead of O(N)
Longer exposure times less noise Inexpensive setup Only controllable binary light source Future Work Smoothness constraints
Using specular and diffuse components Surface adaptive patterns Colored patterns instead of binary Hemispherical light source Questions? Summary Efficient Inexpensive setup
O(log N) instead of O(N) Longer exposure times less noise Inexpensive setup Only controllable binary light source