Accelerated Ray Tracing Research Articles

An Accelerated Ray Tracing Method based on Embree3 Ray Tracing Library for Targets with Non-uniform Thickness Materials

This paper proposes an accelerated ray tracing method utilizing the Embree3 ray tracing library for targets with non-uniform thickness materials. In contrast to the traditional surface-based ray tracing, the proposed approach performs ray tracing within the materials, since surface tracing is ineffective for materials with non-uniform thickness. To ensure efficiency and handle the overlapping grids between different materials, the Embree3 ray tracing library is introduced to ray intersection. Numerical results confirm that the proposed method surpasses existing methods in terms of efficiency and applicability while maintaining accuracy.

Towards Quantum Ray Tracing.

Rendering on conventional computers is capable of generating realistic imagery, but the computational complexity of these light transport algorithms is a limiting factor of image synthesis. Quantum computers have the potential to significantly improve rendering performance through reducing the underlying complexity of the algorithms behind light transport. This paper investigates hybrid quantum-classical algorithms for ray tracing, a core component of most rendering techniques. Through a practical implementation of quantum ray tracing in a 3D environment, we show quantum approaches provide a quadratic improvement in query complexity compared to the equivalent classical approach. Based on domain specific knowledge, we then propose algorithms to significantly reduce the computation required for quantum ray tracing through exploiting image space coherence and a principled termination criteria for quantum searching. We show results obtained using a simulator for both Whitted style ray tracing, and for accelerating ray tracing operations when performing classical Monte Carlo integration for area lights and indirect illumination.

Accelerating ray tracing engine of BLENDER on the new Sunway architecture

AbstractWith the increasing popularity of high‐resolution displays, there is a growing demand for more realistic rendered images. Ray tracing has become the most effective algorithm for image rendering, but its complexity and large amount of computing data require sophisticated HPC solutions. In this article, we present our efforts to port the ray tracing engine CYCLES of Blender to the new generation of Sunway supercomputers. We propose optimizations that are tailored to the new hardware architecture, including a multi‐level parallel scheme that efficiently maps and scales Blender onto the novel Sunway architecture, strategies to address memory bottlenecks, a revised task dispatching method that achieves excellent load balancing, and a pipeline approach that maximizes computation and communication overlap. By combining all these optimizations, we achieve a significant reduction in rendering time for a single‐frame image, from 2260 s using the single‐core serial version to 71 s using 48 processes, which is a speedup of about 128×. Accelerating the ray tracing engine CYCLES of Blender in the new generation of Sunway supercomputers.

Hardware accelerated ray-tracing in ocean acoustics

Due to the expense and complexity of real-world data collection, machine learning applications in ocean acoustics demand ever-faster and more realistic models for training. In this talk, I discuss some recent GPU technologies which support hardware accelerated ray tracing and how they can be exploited to boost the throughput of certain types of calculations. Firstly, I describe RTX-Prop, which is a large-scale range-dependent Gaussian beam model which benefits from hardware-acceleration of bounding volume hierarchy searches and geometry intersection calculations. Designed to ingest oceanographic forecasts from the Royal Australian Navy’s Bluelink system, RTX-Prop has been developed as an embedded model to support tactical decisions by autonomous underwater vehicles. In the second application, I discuss hardware acceleration in the context of high-frequency sonar simulation. By synthesising fine-scale environmental detail, we have previously shown that simulated imagery can be almost indestinguishable from real data. Simulated sidescan and SAS imagery from our S4 model has recently become the basis of a machine-learning pipeline for training detectors and classifiers for naval mine countermeasures. [Work supported by the Trusted Autonomous Systems Defence Coorperative Research Centre.]

An evaluation of Kd-Trees vs Bounding Volume Hierarchy (BVH) acceleration structures in modern CPU architectures

Ray tracing is a rendering technique that is highly praised for its realism and image quality. Nonetheless, this is a computationally intensive task that is slow compared to other rendering techniques like rasterization. Bounding Volume Hierarchy (BVH) is a primitive subdivision acceleration mechanism that is the mainly used method for accelerating ray tracing in modern solutions. It is regarded as having better performance against other acceleration methods. Another well-known technique is Kd-Trees that uses binary space partitioning to adaptively subdivide space with planes. In this research, we made an up-to-date evaluation of both acceleration structures, using state-of-the-art BVH and Kd-Trees algorithms implemented in C, and found out that the Kd-Trees acceleration structure provided better performance in all defined scenarios on a modern x86 CPU architecture.

Mach-RT: A Many Chip Architecture for High Performance Ray Tracing.

Data movement, particularly access to the main memory, has been the bottleneck of most computing problems. Ray tracing is no exception. We propose an unconventional solution that combines a ray ordering scheme that minimizes access to the scene data with a large on-chip buffer acting as near-compute storage that is spread over multiple chips. We demonstrate the effectiveness of our approach by introducing Mach-RT (Many chip - Ray Tracing), a new hardware architecture for accelerating ray tracing. Extending the concept of dual streaming, we optimize the main memory accesses to a level that allows the same memory system to service multiple processor chips at the same time. While a multiple chip solution might seem to imply increased energy consumption as well, because of the reduced memory traffic we are able to demonstrate, performance increases while maintaining reasonable energy usage compared to academic and commercial architectures. This article extends our previous work E. Vasiou, K. Shkurko, E. Brunvand, and C. Yuksel, "Mach-RT: A many chip architecture for high-performance ray tracing," in Proc. High-Perform. Graph. Conf., 2019 with design space exploration of the L3 cache size, more detailed evaluation of energy and memory performance, a discussion of energy delay product, and a brief exploration of boards with 16 chips. We also introduce new treelet enqueueing logic for the predictive scheduler.

Sub-triangle opacity masks for faster ray tracing of transparent objects

We propose an easy and simple-to-integrate approach to accelerate ray tracing of alpha-tested transparent geometry with a focus on Microsoft® DirectX® or Vulkan® ray tracing extensions. Pre-computed bit masks are used to quickly determine fully transparent and fully opaque regions of triangles thereby skipping the more expensive alpha-test operation. These bit masks allow us to skip up to 86% of all transparency tests, yielding up to 40% speed up in a proof-of-concept DirectX® software only implementation.

RTX on—The NVIDIA Turing GPU

NVIDIA's latest processor family, the Turing GPU, was designed to realize a vision for next-generation graphics combining rasterization, ray tracing, and deep learning. It includes fundamental advancements in several key areas: streaming multiprocessor efficiency, a Tensor Core for accelerated AI inferencing, and an RTCore for accelerated ray tracing. With these innovations, Turing unlocks both real-time ray-tracing performance and deep-learning inference in consumer, professional, and datacenter solutions.

Accelerating Ray Tracing with Origin Offsets

Accelerating Ray Tracing with Origin Offsets

On the eigenmodes of periodic orbits for multiple scattering problems in 2D

Wave propagation and acoustic scattering problems require vast computational resources to be solved accurately at high frequencies. Asymptotic methods can make this cost potentially frequency independent by explicitly extracting the oscillatory properties of the solution. However, the high-frequency wave pattern becomes very complicated in the presence of multiple scattering obstacles. We consider a boundary integral equation formulation of the Helmholtz equation in two dimensions involving several obstacles, for which ray tracing schemes have been previously proposed. The existing analysis of ray tracing schemes focuses on periodic orbits between a subset of the obstacles. One observes that the densities on each of the obstacles approach an equilibrium with an increasing number of reflections. In this paper we present an asymptotic approximation of the phases of those densities in equilibrium, in the form of a Taylor series. The densities represent a full cycle of reflections in a periodic orbit. We initially exploit symmetry in the case of two circular scatterers, but also provide an explicit algorithm for a finite number of 2D obstacles satisfying suitable geometrical conditions. The coefficients, as well as the time to compute them, are independent of the wavenumber and of the incident wave. After further research, the results may be used to accelerate ray tracing schemes after a small number of initial iterations.

Fast Hardware Construction and Refitting of Quantized Bounding Volume Hierarchies

AbstractThere is recent interest in GPU architectures designed to accelerate ray tracing, especially on mobile systems with limited memory bandwidth. A promising recent approach is to store and traverse Bounding Volume Hierarchies (BVHs), used to accelerate ray tracing, in low arithmetic precision. However, so far there is no research on refitting or construction of such compressed BVHs, which is necessary for any scenes with dynamic content. We find that in a hardware‐accelerated tree update, significant memory traffic and runtime savings are available from streaming, bottom‐up compression. Novel algorithmic techniques of modulo encoding and treelet‐based compression are proposed to reduce backtracking inherent in bottom‐up compression. Together, these techniques reduce backtracking to a small fraction. Compared to a separate top‐down compression pass, streaming bottom‐up compression with the proposed optimizations saves on average 42% of memory accesses for LBVH construction and 56% for refitting of compressed BVHs, over 16 test scenes. In architectural simulation, the proposed streaming compression reduces LBVH runtime by 20% compared to a single‐precision build, and 41% compared to a single‐precision build followed by top‐down compression. Since memory traffic dominates the energy cost of refitting and LBVH construction, energy consumption is expected to fall by a similar fraction.

GPU Ray Tracing using Irregular Grids

We present a spatial index structure to accelerate ray tracing on GPUs. It is a flat, non-hierarchical spatial subdivision of the scene into axis aligned cells of varying size. In order to construct it, we first nest an octree into each cell of a uniform grid. We then apply two optimization passes to increase ray traversal performance: First, we reduce the expected cost for ray traversal by merging cells together. This adapts the structure to complex primitive distributions, solving the teapot in a stadium problem. Second, we decouple the cell boundaries used during traversal for rays entering and exiting a given cell. This allows us to extend the exiting boundaries over adjacent cells that are either empty or do not contain additional primitives. Now, exiting rays can skip empty space and avoid repeating intersection tests. Finally, we demonstrate that in addition to the fast ray traversal performance, the structure can be rebuilt efficiently in parallel, allowing for ray tracing dynamic scenes.

An Accelerated Ray Tracing Method Based on the TSM for the RCS Prediction of 3-D Large-Scale Dielectric Sea Surface

An accelerated ray tracing method based on the two-scale model for the radar-cross-section prediction of 3-D large-scale dielectric sea surface is proposed in this letter. For the accelerated ray tracing method, the sea surface is constructed into a great deal of large triangles that consist of many small triangles; this is called the two-scale model. Then, each ray is traced until it does not have any intersection with the large triangles. At the scattered large triangles, the Physical Optics method is performed to obtain the scattered far fields, which is the summation of scattered field from each small triangle. The comparison to the traditional accelerated ray tracing method is given to demonstrate the accuracy and capability of the new accelerated ray tracing method. Compared to the traditional accelerated ray tracing method, the proposed accelerated ray tracing method can dramatically decrease the computational time.

New ray tracing method to investigate the various effects on wave propagation in medical scenario: an application of wireless body area network.

The advent of technology with the increasing use of wireless network has led to the development of Wireless Body Area Network (WBAN) to continuously monitor the change of physiological data in a cost efficient manner. As numerous researches on wave propagation characterization have been done in intrabody communication, this study has given emphasis on the wave propagation characterization between the control units (CUs) and wireless access point (AP) in a hospital scenario. Ray tracing is a tool to predict the rays to characterize the wave propagation. It takes huge simulation time, especially when multiple transmitters are involved to transmit physiological data in a realistic hospital environment. Therefore, this study has developed an accelerated ray tracing method based on the nearest neighbor cell and prior knowledge of intersection techniques. Beside this, Red-Black tree is used to store and provide a faster retrieval mechanism of objects in the hospital environment. To prove the superiority, detailed complexity analysis and calculations of reflection and transmission coefficients are also presented in this paper. The results show that the proposed method is about 1.51, 2.1, and 2.9 times faster than the Object Distribution Technique (ODT), Space Volumetric Partitioning (SVP), and Angular Z-Buffer (AZB) methods, respectively. To show the various effects on received power in 60 GHz frequency, few comparisons are made and it is found that on average −9.44 dBm, −8.23 dBm, and −9.27 dBm received power attenuations should be considered when human, AP, and CU move in a given hospital scenario.

Reducing Render Time in Ray Tracing by Pixel Averaging

Many computer graphics rendering algorithms and techniques use ray tracing for generatingnatural and photo-realistic images. Ray tracing is a method to convert 3D-modeles into 2D-high quality images by complex computation. The millions of rays must be simulated and traced to create realistic image. A method for reducing render time is acceleration structures. The kd -tree is the most commonly used in accelerating ray tracing algorithms. This paper has focused on reducing render time. We propose tow methods that are combined with ray tracing method for obtaining some pixel colour of image plane . Our methods are linear algorithm and arefaster than ray tracing method. Our results show that our methods are at least 50% faster than spatial median approach for reasonably complex scenes with around 70k polygons and about 0.2% quality degradation. In this article, we show that these proposal methods canbe combined with other ray tracing methodssuch as SAH to reduce render time.

On the Generation of Ground Truth Data for Depth Reconstruction

Acquiring data sets for stereo or multi-view reconstruction with known ground truth is costly and time consuming. Freely available data sets mostly focus on specific scene conditions and might not reflect the intended application scenario. We propose a GPU accelerated ray tracing framework that allows to generate realistic images with adjustable camera properties and projection geometry. Due to the nature of ray tracing, ground truth data can easily be obtained. The system also supports projectors as used e.g. for structured light systems. This facilitates to study interaction effects between different pattern designs, camera and projector properties, as well as the utilized reconstruction algorithm.

Accelerated ray tracing for radiotherapy dose calculations on a GPU

The graphical processing unit (GPU) on modern graphics cards offers the possibility of accelerating arithmetically intensive tasks. By splitting the work into a large number of independent jobs, order-of-magnitude speedups are reported. In this article, the possible speedup of PLATO's ray tracing algorithm for dose calculations using a GPU is investigated. A GPU version of the ray tracing algorithm was implemented using NVIDIA's CUDA, which extends the standard C language with functionality to program graphics cards. The developed algorithm was compared based on the accuracy and speed to a multithreaded version of the PLATO ray tracing algorithm. This comparison was performed for three test geometries, a phantom and two radiotherapy planning CT datasets (a pelvic and a head-and-neck case). For each geometry, four different source positions were evaluated. In addition to this, for the head-and-neck case also a vertex field was evaluated. The GPU algorithm was proven to be more accurate than the PLATO algorithm by elimination of the look-up table for z indices that introduces discretization errors in the reference algorithm. Speedups for ray tracing were found to be in the range of 2.1-10.1, relative to the multithreaded PLATO algorithm running four threads. For dose calculations the speedup measured was in the range of 1.5-6.2. For the speedup of both the ray tracing and the dose calculation, a strong dependency on the tested geometry was found. This dependency is related to the fraction of air within the patient's bounding box resulting in idle threads. With the use of a GPU, ray tracing for dose calculations can be performed accurately in considerably less time. Ray tracing was accelerated, on average, with a factor of 6 for the evaluated cases. Dose calculation for a single beam can typically be carried out in 0.6-0.9 s for clinically realistic datasets. These findings can be used in conventional planning to enable (nearly) real-time dose calculations. Also the importance for treatment optimization techniques is evident.

The Use of Precomputed Triangle Clusters for Accelerated Ray Tracing in Dynamic Scenes

AbstractIn this paper we present a hybrid algorithm for building the bounding volume hierarchy (BVH) that is used in accelerating ray tracing of animated models. This algorithm precomputes densely packed clusters of triangles on surfaces. Folowing that, a set of clusters is used to rebuild the BVH in every frame. Our approach utilizes the assumption that groups of connected triangles remain connected throughout the course of the animation. We introduce a novel heuristic to create triangle clusters that are designed for high performance ray tracing. This heuristic combines the density of connectivity, geometric size and the shape of the cluster.Our approach accelerates the BVH builder by an order of magnitude rebuilding only the set of clusters that is much smaller than the original set of triangles. The speed‐up is achieved against a ‘brute‐force’ BVH builder that repartitions all triangles in every frame of animation without using any pre‐clustering. The rendering performance is not affected when a cluster contains a few dozen triangles. We demonstrate the real‐time/interactive ray tracing performance for highly‐dynamic complex models.

Coherent Path Tracing

Packet tracing is a popular and efficient method for accelerating ray tracing. However, packet traversal techniques become inefficient when they are applied to path tracing since the secondary rays are incoherent. In this paper, we present a simple technique for improving the coherency of secondary rays. This technique uses the same sequence of random numbers for generating secondary rays for all the pixels in each sample. This improves the efficiency of the packet tracing algorithm but creates structured noise patterns in the image. We propose an interleaved sampling scheme that reduces the correlation in the noise and makes it virtually imperceptible in the final image. Coherent path tracing is unbiased, simple to implement, and outperforms standard path tracing with packet tracing, while producing images with similar RMS error values.

Accelerating Ray Tracing using Constrained Tetrahedralizations

AbstractIn this paper we introduce the constrained tetrahedralization as a new acceleration structure for ray tracing. A constrained tetrahedralization of a scene is a tetrahedralization that respects the faces of the scene geometry. The closest intersection of a ray with a scene is found by traversing this tetrahedralization along the ray, one tetrahedron at a time. We show that constrained tetrahedralizations are a viable alternative to current acceleration structures, and that they have a number of unique properties that set them apart from other acceleration structures: constrained tetrahedralizations are not hierarchical yet adaptive; the complexity of traversing them is a function of local geometric complexity rather than global geometric complexity; constrained tetrahedralizations support deforming geometry without any effort; and they have the potential to unify several data structures currently used in global illumination.