SIGGRAPH Asia 2018
Antoine Toisoul* Daljit Singh Dhillon* Abhijeet Ghosh
Imperial College London
Fig. 1: Acquired holographic surfaces rendered in real-time under environmental illumination. (a) Holographic paper with a repeating star pattern acquired using flash illumination. (b) Holographic paper with a stochastic texture acquired using flash illumination. (c) A holographic SIGGRAPH logo from a SIGGRAPH 2015 registration badge acquired using polarization imaging. Insets show HSV color visualization of the estimated grating orientation maps.
Abstract: We present two novel and complimentary approaches to measure diffraction effects in commonly found planar spatially varying holographic surfaces. Such surfaces are increasingly found in various decorative materials such as gift bags, holographic papers, clothing and security holograms, and produce impressive visual effects that have not been previously acquired for realistic rendering. Such holographic surfaces are usually manufactured with one dimensional diffraction gratings that are varying in periodicity and orientation over an entire sample in order to produce a wide range of diffraction effects such as gradients and kinematic (rotational) effects. Our proposed methods estimate these two parameters and allow an accurate reproduction of these effects in real-time. The first method simply uses a point light source to recover both the grating periodicity and orientation in the case of regular and stochastic textures. Under the assumption that the sample is made of the same repeated diffractive tile, good results can be obtained using just one to five photographs on a wide range of samples. The second method is based on polarization imaging and enables an independent high resolution measurement of the grating orientation and relative periodicity at each surface point. The method requires a minimum of four photographs for accurate results, does not assume repetition of an exemplar tile, and can even reveal minor fabrication defects. We present point light source renderings with both approaches that qualitatively match photographs, as well as real-time renderings under complex environmental illumination.
(* Joint first authors)
Publication: Acquiring Spatially Varying Appearance of Printed Holographic Surfaces. Antoine Toisoul*, Daljit Singh Dhillon*, Abhijeet Ghosh. ACM Transactions on Graphics (Proc. SIGGRAPH Asia), 37(6), 2018. (* Joint first authors)
