Point-Based Rendering for Homogeneous Participating Media with Refractive Boundaries

IEEE Trans. Visual. Comput. Graphics

et al. 2021

Self Cite

Rendering participating media is important to the creation of photorealistic images. Participating media has a translucent aspect that comes from light being scattered inside the material. For materials with a small mean-free path, multiple scattering effects dominate. Simulating these effects is computationally intensive, as it requires tracking a large number of scattering events inside the material. Existing approaches precompute multiple scattering events inside the material and store the results in a table during rendering time, this table is used to compute the scattering effects. While these methods are faster than explicit scattering computation, they incur higher storage costs. In this paper, we present a new representation for double and multiple scattering effects that uses a neural network model. The scattering response from all homogeneous participating media is encoded into a neural network in a preprocessing step. At run time, the neural network is then used to predict the double and multiple scattering effects. We demonstrate the effects combined with Virtual Ray Lights (VRL), although our approach can be integrated with other rendering algorithms. Our algorithm is implemented on a GPU. Double and multiple scattering effects for the entire participating media space are encoded using only 23.6 KB of memory. Our method achieves a rendering times of 50 ms per frame in typical scenes and provides results almost identical to the reference.

Section: Precomputation-based Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interactive Simulation of Scattering Effects in Participating Media Using a Neural Network Model

IEEE Trans. Visual. Comput. Graphics

et al. 2021

Self Cite

“…Adapting the kernel size to frequency information allows us to provide sharp volume caustics with much fewer volume samples, greatly reducing both the memory footprint and the cost of the preprocessing step. Our method provides pictures with better quality and smaller computation time compared to Wang et al [3].…”

Section: Introductionmentioning

confidence: 92%

“…These methods are accurate, but also very expensive and highly dependent on scene complexity (triangle count). Point based methods by Wang et al [3] are faster and solve for both high-order scattering (more than two scattering events) and low-order scattering, including single scattering. They work in two steps: in a preprocessing step, they distribute volume samples, caching both the geometry and illumination information, and organize them into a spatial hierarchy.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we introduce tools for frequency analysis of light transport [4] into the point-based illumination method by Wang et al [3]. Specifically, we use covariance tracing, by Belcour et al [5], [6], to compute the local frequency content for single scattering effects, using the covariance matrix of the frequency spectrum of the local light field.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fast Computation of Single Scattering in Participating Media with Refractive Boundaries Using Frequency Analysis

Liang

IEEE Trans. Visual. Comput. Graphics

et al. 2020

Self Cite

Many materials combine a refractive boundary and a participating media on the interior. If the material has a low opacity, single scattering effects dominate in its appearance. Refraction at the boundary concentrates the incoming light, resulting in an important phenomenon called volume caustics. This phenomenon is hard to simulate. Previous methods used point-based light transport, but attributed point samples inefficiently, resulting in long computation time. In this paper, we use frequency analysis of light transport to allocate point samples efficiently. Our method works in two steps: in the first step, we compute volume samples along with their covariance matrices, encoding the illumination frequency content in a compact way. In the rendering step, we use the covariance matrices to compute the kernel size for each volume sample: small kernel for high-frequency single scattering, large kernel for lower frequencies.Our algorithm computes volume caustics with fewer volume samples, with no loss of quality. Our method is both faster and uses less memory than the original method. It is roughly twice as fast and uses one fifth of the memory. The extra cost of computing covariance matrices for frequency information is negligible.

A survey on rendering homogeneous participating media

Yan

2021

Comp. Visual Media

Self Cite

Participating media are frequent in real-world scenes, whether they contain milk, fruit juice, oil, or muddy water in a river or the ocean. Incoming light interacts with these participating media in complex ways: refraction at boundaries and scattering and absorption inside volumes. The radiative transfer equation is the key to solving this problem. There are several categories of rendering methods which are all based on this equation, but using different solutions. In this paper, we introduce these groups, which include volume density estimation based approaches, virtual point/ray/beam lights, point based approaches, Monte Carlo based approaches, acceleration techniques, accurate single scattering methods, neural network based methods, and spatially-correlated participating media related methods. As well as discussing these methods, we consider the challenges and open problems in this research area.