Real-time Image-based Lighting of Microfacet BRDFs with Varying Iridescence

In: Computer Graphics Forum (Juli 2019), 38:4
 

Abstract

Iridescence is a natural phenomenon that is perceived as gradual color changes, depending on the view and illumination direction. Prominent examples are the colors seen in oil films and soap bubbles. Unfortunately, iridescent effects are particularly difficult to recreate in real-time computer graphics. We present a high-quality real-time method for rendering iridescent effects under image-based lighting. Previous methods model dielectric thin-films of varying thickness on top of an arbitrary micro-facet model with a conducting or dielectric base material, and evaluate the resulting reflectance term, responsible for the iridescent effects, only for a single direction when using real-time image-based lighting. This leads to bright halos at grazing angles and over-saturated colors on rough surfaces, which causes an unnatural appearance that is not observed in ground truth data. We address this problem by taking the distribution of light directions, given by the environment map and surface roughness, into account when evaluating the reflectance term. In particular, our approach prefilters the first and second moments of the light direction, which are used to evaluate a filtered version of the reflectance term. We show that the visual quality of our approach is superior to the ones previously achieved, while having only a small negative impact on performance.

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Zusätzliches Material

Bibtex

@ARTICLE{kneiphof-2019-iridescence,
    author = {Kneiphof, Tom and Golla, Tim and Klein, Reinhard},
     title = {Real-time Image-based Lighting of Microfacet BRDFs with Varying Iridescence},
   journal = {Computer Graphics Forum},
    volume = {38},
    number = {4},
      year = {2019},
     month = jul,
  abstract = {Iridescence is a natural phenomenon that is perceived as gradual color changes, depending on the
              view and illumination direction. Prominent examples are the colors seen in oil films and soap
              bubbles. Unfortunately, iridescent effects are particularly difficult to recreate in real-time
              computer graphics. We present a high-quality real-time method for rendering iridescent effects under
              image-based lighting. Previous methods model dielectric thin-films of varying thickness on top of an
              arbitrary micro-facet model with a conducting or dielectric base material, and evaluate the
              resulting reflectance term, responsible for the iridescent effects, only for a single direction when
              using real-time image-based lighting. This leads to bright halos at grazing angles and
              over-saturated colors on rough surfaces, which causes an unnatural appearance that is not observed
              in ground truth data. We address this problem by taking the distribution of light directions, given
              by the environment map and surface roughness, into account when evaluating the reflectance term. In
              particular, our approach prefilters the first and second moments of the light direction, which are
              used to evaluate a filtered version of the reflectance term. We show that the visual quality of our
              approach is superior to the ones previously achieved, while having only a small negative impact on
              performance.}
}