We propose two novel contributions for measurement based rendering of
diffraction effects in surface reflectance of planar homogeneous diffractive
materials. As a general solution for commonly manufactured materials, we
propose a practical data-driven rendering technique and a measurement
approach to efficiently render complex diffraction effects in real-time. Our
measurement step simply involves photographing a planar diffractive sam-
ple illuminated with an LED flash. Here, we directly record the resultant
diffraction pattern on the sample surface due to a narrow band point source
illumination. Furthermore, we propose an efficient rendering method that
exploits the measurement in conjunction with the Huygens-Fresnel principle
to fit relevant diffraction parameters based on a first order approximation.
Our proposed data-driven rendering method requires the precomputation
of a
single
diffraction look up table for accurate spectral rendering of com-
plex diffraction effects. Secondly, for sharp specular samples, we propose
a novel method for practical measurement of the underlying diffraction
grating using out-of-focus “bokeh” photography of the specular highlight.
We demonstrate how the measured bokeh can be employed as a height
field to drive a diffraction shader based on a first order approximation for
efficient real-time rendering. Finally, we also drive analytic solutions for a
few special cases of diffraction from our measurements and demonstrate
realistic rendering results under complex light sources and environments.