Realistic woven fabric rendering plays an important role in film production, video games, etc. The microflake model has recently been introduced for lightweight fabric rendering, which serves as the specular part of the woven fabric appearance. However, it cannot be used directly for real-time rendering due to the low sample count requirements for real-time rendering. The main challenge is a multi-scale representation which allows for efficient range query during rendering. To this end, we propose a multi-scale representation of the specular lobes of each yarn segment using SGGX fitting. More specifically, we precompute the normal distribution functions (NDFs) of the yarn segments with different query sizes and then use several SGGX functions to represent the NDFs. During rendering, we aggregate the contribution for each pixel by querying the fitted SGGXs of yarn segments covered by the pixel's footprint. We also propose a bounding box representation for the yarn segments, enabling a practical intersection with the pixel's footprint. As a result, our method is able to render several typical types of woven fabrics in only 1–2 ms at 1080p resolution using an RTX 3090 video card. Our method outperforms existing approaches and shows closer rendering results to reference results.

Many real-life materials have sparkling appearances. Some small flakes on the surface of an object can make a considerable contribution by reflecting or refracting light at a particular angle, eventually causing a sparkling appearance. Most existing approaches have focused on the glinty effects on reflective surfaces. However, transparent glint rendering has not been well studied, even though there are many natural phenomena (e.g., frost) in the real world. Recent studies have proposed the simulation of transparent glints under specific constraints (e.g., limited to the Beckmann distribution and V-groove shadowing-masking function). In this study, we propose a more general transparent glint model by performing a four-dimensional hierarchical search to count the particles located in the pixel footprint and cone around the refracted ray. Our method can produce transparent glint appearances for arbitrary normal distribution functions (e.g., GGX or Beckmann) and converge to a smooth microfacet model with a large particle count.