An implementation of ray tracing algorithm for the multiprocessor machines (original) (raw)
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A parallel implementation of an interactive ray-tracing algorithm
Computing Systems in Engineering, 1995
One of the most-used rendering algorithms in Computer Graphics is the Ray-Tracing. The “standard” (Whited like) Ray-Tracing is a good rendering algorithm but with a drawback: the time necessary to produce an image is too large (several hours of CPU time are necessary to make a good picture of a moderately sophisticated 3D scene) and the image is only ready to be observed at the end of processing. This kind of situation is difficult to accept in systems where interactivity is the first goal. “Increasing Realism” in Ray-Tracing tries to avoid the problem by supplying the user with a preview of the final image. This preview can be calculated in a considerably shorter time but permits that, with some margin of error, the user can imagine (even see, sometimes) some final effects. With more processing time the image quality continues improving without loss of previous results. The user can, at any time, interrupt the session if the image does not match what he wants. Simultaneously with the above idea, it is necessary to accelerate image production. Parallelism is then justified by the need of more processing power. The aim of this text is to describe the Interactive Ray-Tracing Algorithm implementation, using a parallel architecture based on Transputers. An overview of the architecture used is presented and the main parallel processes and related problems are discussed.
Parallel implementation of an interactive ray-tracing algorithm
Computing Systems in Engineering, 1995
One of the most-used rendering algorithms in Computer Graphics is the Ray-Tracing. The "'standard" (Whited like) Ray-Tracing ~ is a good rendering algorithm but with a drawback: the time necessary to produce an image is too large (several hours of CPU time are necessary to make a good picture of a moderately sophisticated 3D scene) and the image is only ready to be observed at the end of processing. This kind of situation is difficult to accept in systems where interactivity is the first goal. "Increasing Realism" in Ray-Tracing tries to avoid the problem by supplying the user with a preview of the final image. This preview can be calculated in a considerably shorter time but permits that, with some margin of error, the user can imagine (even see, sometimes) some final effects. With more processing time the image quality continues improving without loss of previous results. The user can, at any time, interrupt the session if the image does not match what he wants. Simultaneously with the above idea, it is necessary to accelerate image production. Parallelism is then justified by the need of more processing power. The aim of this text is to describe the Interactive Ray-Tracing Algorithm implementation, using a parallel architecture based on Transputers. An overview of the architecture used is presented and the main parallel processes and related problems are discussed.
A flexible algorithm for multiprocessor ray tracing
The Computer Journal, 1998
Ray tracing programs are widely used to generate photo-realistic images, but the high computation time may discourage their implementation on single-processor machines; moreover, cost reduction of multi-processor general purpose architectures makes parallel rendering an attractive ...
TWO ALTERNATIVE PARALLEL IMPLEMENTATIONS FOR RAY TRACING: OPENMP AND MPI
In computer graphics, rendering scenes into high-quality images efficiently is critical, especially if some interactivity is required. However, it is hard to satisfy both speed and interactivity requirements for most existing rendering algorithms. Ray Tracing is an algorithm for three-dimensional scene rendering, but it needs massive heavy floating-point computations. Nevertheless, the algorithm can be very well parallelized, making it ideal for parallel mutli-core architectures. In this paper, we present a structured model for parallel Ray Tracing together with two software implementations in OpenMP and MPI. The model is based on the Uniform Grid spatial subdivision of the scene, which allows for intersection test reduction. Furthermore, we show that a parallel implementation improves the algorithm performance when the rendered scenes are large and sparse.
Exploitation of image parallelism for ray tracing 3D scenes on 2D mesh multicomputers
Parallel Computing, 1997
Ray tracing is a well known technique to generate lifelike images based on models of light shading, reflection, and refraction. The massive computation and memory demands of ray tracing complex scenes have long motivated researchers to use parallel processing in reducing the ray tracing time. This paper gives a study of parallel implementation of a ray tracing algorithm on a distributed memory parallel computer. The computational cost of rendering pixels and patterns of data access can not be predicted until runtime. To efficiently parallelize such an application, the issues of database partition, data management and load balancing must be addressed. In this paper, we discuss the ways of database partition and propose a dynamic data management scheme which can exploit image coherence to reduce data communication time. A global load balancing mechanism is presented to ensure a good load balance among processors during ray tracing time. The success of our implementation depends crucially on a number of parameters which are experimentally evaluated.
Rendering large scenes using parallel ray tracing
Parallel Computing, 1997
Ray tracing is a powerful technique to generate realistic images of 3D scenes. However, the rendering of complex scenes may easily exceed the processing and memory capabilities of a single workstation. Distributed processing offers a solution if the algorithm can be parallelised in an efficient way. In this paper a hybrid scheduling approach is presented that combines demand driven and data parallel techniques. Which tasks to process demand driven and which data driven, is decided by the data intensity of the task and the amount of data locality (coherence) that will be present in the task. By combining demand driven and data driven tasks, a good load balance is achieved, while at the same time spreading the communication evenly across the network. This leads to a scalable and efficient parallel implementation of the ray tracing algorithm with fairly no restriction on the size of the model data base to be rendered.
An efficient parallel architecture for ray-tracing
Real time rendering of three-dimensional scenes in high photorealistic details is a hard task, such as in the ray tracing rendering algorithm. In general, the performance achieved by a sequential software-based implementation of ray tracing is far from satisfactory. However, parallel implementations of ray tracing have been enabling reasonable real time performance, as the algorithm is embarrassingly parallel. Thus, a custom parallel design in hardware is likely to achieve an even higher performance. In this paper, we propose a hardware parallel architecture capable of dealing with the main desirable features of ray tracing, such as shadows and reflection effects, imposing low area cost and a promising rendering performance. Such architecture, called GridRT, is based on the Uniform Grid acceleration structure and is intended to deliver massive parallelism through parallel ray-triangle intersection tests as well as parallel processing of many rays. A hardware implementation of the proposed architecture is presented, together with some performance results and resources requirements. The rendering is reduced by 80% using a grid configuration of eight processing elements.
2007
Ray tracing is a technique for rendering images from a three dimensional model of a scene by projecting it on to a two dimensional image plane. It works by calculating the direction of the ray that strikes each pixel of the image plane, and tracing that ray back into the scene to determine the interaction of lights and surfaces that produced that ray. Raster graphics systems, such as OpenGL, use approximations and computational short cuts to allow rendering scenes in real time at the cost of image quality. Ray tracing, on the other hand, produces higher quality images (see Figure 1), but is too slow to be used in real time. Since the calculations for each pixel are independent, ray tracing can be easily parallelizable. Parallelization is one way to close the gap in execution time between ray tracing and traditional raster graphics systems. The algorithm we are implementing is not so sophisticated; it is little more than the basic naive implementation. Therefore, we expect to achieve...
A parallel system for non-deterministic ray tracing
. Difference between results of graphic card like algorithm (left), classic ray tracing (middle) and full global illumination (right). All guessed lighting terms (e.g. ambient light) were disabled deliberately, to show what given technique actually computes.
Parallel ray tracing on the IBM SP2 and CRAY T3D
1995
Raytracing is a widely used method for generating realistic-looking images on a computer, but it still requires considerable computing p ower, especially when rendering complex scenes. This paper presents a parallel raytracing algorithm with dynamic workload distribution, based on public domain raytracing software Rayshade. The implementation on the IBM SP2 and CRAY T3D is presented, with the discussion of