| In real-world lighting situations,many materials have a high-frequency varying sparkling appearance.It is caused by the fact that a small part of the numerous microscopic surfaces on the surface of the object forms a near-perfect mirror reflection or refraction,and the energy carried by the sharp and intense light source incident on the positions of these microscopic structures is scattered to the observation position in a large proportion,then observed by human eyes.In the field of highly photorealistic rendering,the high-performance appearance detail material model plays an important role in enhancing the photorealistic of 3D scenes.Traditional material models tend to make images "greasy",monotonous,or physical-incorrectly lit.Excellent metal,leather,hair,and other material models can play a very real effect.Recently,there are several methods to simulate the glint phenomenon caused by the reflection of the surface.However,glint phenomena on transparent surfaces are also widespread in reality(such as etched glass,thin frost,and dense water droplets)and have not been well studied and simulated.The only recent study was able to simulate transparent glints,but its approach was more constrained(only supporting Beckmann normal distribution and V-cavity shadow-masking function).In this paper,we propose a more general transparent glint model,which’s key ideas are as follows:It is assumed that the surface of the object is evenly distributed with a certain number of small particles with their orientations.For a rendered pixel,the 4D hierarchy is used to quickly search and calculate how many particles can scatter the incident light into the pixel footprint region,to obtain the energy value.Our method can generate a transparent glint appearance according to the arbitrary surface normal distribution functions(e.g.GGX distribution or Beckmann distribution),and experimental results show that the material appearance converges to the traditional smooth microfacet model with increasing particle number.The complexity of the model has a logarithmic relationship with the total number of discrete particles specified.Under the common Settings of experiments in this paper,the average time cost is roughly twice that of the traditional smooth microfacet model but can achieve an exquisite appearance with glossy details.The model presented in this paper can be initially applied to rendering scenes with highly realistic etched glass and thin frost materials.The traditional smooth and transparent material model will make the surface gloss too perfect,smooth,and uniform in practical application,so that the drawing result is not realistic enough.Our model can be used to create surfaces that shine under intense light conditions,providing a logical,controllable,and animation coherent form of noise to increase visual richness. |
