Shooting and Bouncing Ray algorithm is widely used to predict the features of radio wave *** the features of simulation environment for dynamic emission and tracing can effectively reduce the number of rays that need ...
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Shooting and Bouncing Ray algorithm is widely used to predict the features of radio wave *** the features of simulation environment for dynamic emission and tracing can effectively reduce the number of rays that need to be tracked,and improve the efficiency of *** paper proposes an improved algorithm for dynamic emission and tracing rays Based on the existing dynamic tracking method,and the improved algorithm can be used in outdoor environment and with high efficiency.
This paper presents a novel method to model wave effects in a ray tracer which attempts to account for the attenuation, scattering and absorption of light affected by participating media along rays. Inspired by diffra...
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This paper presents a novel method to model wave effects in a ray tracer which attempts to account for the attenuation, scattering and absorption of light affected by participating media along rays. Inspired by diffraction shaders (DS), we propose an extension of this model to construct a new Bidirectional Reflectance Distribution Function (BRDF) to simultaneously take into consideration the phase and amplitude variation of light. The new method can simulate diffraction effects of a variety of materials, where we introduce the Fresnel factor and a microfacet scattering metric which affect the absorption and geometrical attenuation of photons. Incorporating Wigner Distribution Function (WDF), our method is further extended to model interference effects after multiple bounces by deferring the phase calculation. An acceleration algorithm is also implemented to real-time model diffraction effects of different apertures. We demonstrate the validity of our method by generating wave patterns for diverse scenes. (C) 2013 Elsevier Inc. All rights reserved.
Aiming at the requirements for virtual naval battle environmental simulation, we present an ocean wave simulation method. Firstly according to double superposition model based on the ocean wave spectrum and the linear...
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ISBN:
(纸本)9783642343957
Aiming at the requirements for virtual naval battle environmental simulation, we present an ocean wave simulation method. Firstly according to double superposition model based on the ocean wave spectrum and the linear ocean wave theory, using the acceleration algorithm for ocean wave numerical simulation, the method completes the three-dimensional shape of ocean wave, and then introduces vertex array graphics rendering into drawing ocean wave. Lastly, to improve the visual fidelity, with separate specular color and local viewpoint, we achieve ocean wave surface reflected light effects simulation. Through testing and validation, the method can quickly simulate ocean waves, and the simulation result is available.
Aiming at the tremendous computation and the low rate of standard ray casting algorithm, a new speed-up algorithm of ray casting volume rendering was presented to realize the real-time manipulation of medical images. ...
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Aiming at the tremendous computation and the low rate of standard ray casting algorithm, a new speed-up algorithm of ray casting volume rendering was presented to realize the real-time manipulation of medical images. Firstly, with the uniform changes characteristics of primitives before and after matrix transformation, all re-sampling points except for the six vertex were deduced so as to reduce matrix computation greatly. Secondly, the boundary box technique was utilized to avoid the sampling in empty voxel. Thirdly, extending the Bresenham algorithm to three-dimension, casting ray voxelizing and the re-sampling parameters were computed simultaneously, which greatly improved the efficiency of ray casting. All results of a mass of contrasting experiments show that the acceleration algorithm can produce the same quality images as the conventional standard algorithm, but the velocity of volume rendering is increased by two or three times.
Medical image 3D reconstruct is an important application filed for volume rendering, for it special using, it required fast interactive speed and high image quality. The ray casting algorithm (RCA) is a widely used ba...
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ISBN:
(纸本)9780819469533
Medical image 3D reconstruct is an important application filed for volume rendering, for it special using, it required fast interactive speed and high image quality. The ray casting algorithm (RCA) is a widely used basic volume rendering algorithm. It can get high quality image but the rendering speed is very slowly for powerful computing capacity. Due to these shortcomings and deficiencies, the accelerated ray casting algorithm is presented in this paper to improve its rendering speed and apply it to medical image 3D reconstruct. Firstly, accelerate algorithms for ray casting are fully studied and compared. Secondly, improved tri-linear interpolation technology has been selected and extended to continuous ray casting in order to reduce matrix computation by matrix transformation characteristics of re-sampling points. Then ray interval casting technology is used to reduce the number of rays. Utilizing volume data sets cropping technology that improving boundary box technique avoids the sampling in empty voxel. Finally, the synthesized accelerate algorithm has been proposed. The result shown that compare with standard ray casting algorithm, the accelerate algorithm not only improve the rendering speed but also produce the required quality images.
Four problems existing in BP neural network practical application are discussed in this paper: slow converging speed, converging at local minimum, overtraining and poor extrapolating capacity. Comparing advantages and...
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ISBN:
(纸本)9781424413119
Four problems existing in BP neural network practical application are discussed in this paper: slow converging speed, converging at local minimum, overtraining and poor extrapolating capacity. Comparing advantages and disadvantage of several acceleration algorithms, the paper provides the suggestions of solving those problems. The paper also advances a forecasting model of monthly irrigation return flow based on BP neural network is advanced as a case study.
Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key...
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Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key to speed up the ray casting algorithm. An algorithm is introduced to reduce matrix computation by matrix transformation characteristics of re-sampling points in a two coordinate system. The projection of 3-D datasets on image plane is adopted to reduce the number of rays. Utilizing boundary box technique avoids the sampling in empty voxel. By extending the Bresenham algorithm to three dimensions, each re-sampling point is calculated. Experimental results show that a two to three-fold improvement in rendering speed using the optimized algorithm, and the similar image quality to traditional algorithm can be achieved. The optimized algorithm can produce the required quality images, thus reducing the total operations and speeding up the volume rendering.
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