Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
938
result(s) for
"Ray tracing algorithms."
Sort by:
The ray tracer challenge : a test-driven guide to your first 3D renderer
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that renders beautiful scenes with shadows, reflections, refraction effects, and subjects composed of various graphics primitives: spheres, cubes, cylinders, triangles, and more. With each chapter, implement another piece of the puzzle and move the renderer forward. Use whichever language and environment you prefer, and do it entirely test-first, so you know it's correct.
Book
Joint Optimization of 5.5G Cellular Networks Using Ray Tracing and PSO-MDE for Antenna Configuration and Power Allocation
In the continuous evolution of mobile communication technology, 5.5G network is a key step towards future communication, which is gradually becoming the focus of academia and industry. To solve the complex signal propagation and serious multi-path interference in high frequency band, the improved particle swarm differential evolution algorithm and multi-objective differential evolution particle swarm optimization algorithm are proposed to maximum coverage and minimum power consumption in wireless sensor networks. This method improves the efficiency of solving complex optimization problems by maintaining the global search ability and enhancing the local search performance. The experiment was carried out on a customized simulation platform and tested for different scale sensor deployment scenarios. The research results indicated that the optimal coverage after optimizing the parameters of the community antenna occurred when the inertia factor was 0.4 and 0.7, at 0.641 and 0.640, respectively. The average optimal coverage was 0.633 and 0.632 when the inertia factor was 0.6 and 0.7, respectively. The designed algorithm performed the best in reducing transmission power, computational efficiency, and exploring solution space. The minimum total transmission power reached 33.5dBm, the maximum number of Pareto front points reached 240, and the calculation time was the shortest, at 530s. The research results show that the proposed optimization algorithm can effectively improve the coverage and energy efficiency of the 5.5G network, providing an effective solution for network optimization.
Journal Article
An extended laser beam heating model for a numerical platform to simulate multi-material selective laser melting
A laser beam heating model (LBHM) is an important part of a platform for numerical modelling of a multi-material selective laser melting process. The LBHM is utilised as a ray-tracing algorithm that is widely applied for rendering in different applications, mainly for visualisation and very recently for laser heating models in selective laser melting. The model presented in this paper was further extended to transparent and translucent materials, including materials where transparency is dependent on the material temperature. In addition to reflection and surface absorption, commonly considered in such models, phenomena such as refraction, scattering and volume absorption were also implemented. Considering associated energy transfer, the model represents a laser beam as a stream of moving particles, i.e. photons of the same energy. When the photons meet a boundary between materials, they are reflected, absorbed or transmitted according to geometric and thermal interfacial characteristics. This paper describes the LBHM in detail, its verification and validation, and also presents several simulation examples of the entire selective laser melting process with implemented LBHM.
Journal Article
A Hybrid Model for Analysis of Laser Beam Distortions Using Monte Carlo and Shack–Hartmann Techniques: Numerical Study and Experimental Results
The hybrid model for analyzing distortions of a laser beam passed through a moderately scattering medium with the number of scattering events up to 10 is developed and investigated. The model implemented the Monte Carlo technique to simulate the beam propagation through a scattering layer, a ray-tracing technique to propagate the scattered beam to the measurements plane, and the Shack–Hartmann technique to calculate the scattered laser beam distortions. The results obtained from the developed model were confirmed during the laboratory experiment. Both the numerical model and laboratory experiment showed that with an increase of the concentration value of scattering particles in the range from 105 to 106 mm−3, the amplitude of distortions of laser beam propagated through the layer of the scattering medium increases exponentially.
Journal Article
A Calculation Method for the Hyperspectral Imaging of Targets Utilizing a Ray-Tracing Algorithm
This paper proposes a hyperspectral imaging simulation method based on a ray-tracing algorithm. The algorithm combines calculations based on solar and atmospheric visible light radiation as well as the spectral bidirectional reflection distribution function (BRDF) of the target surface material and can create its own scenarios for simulation calculations on demand. Considering the presence of multiple scattering between the target and background, using the ray-tracing algorithm enables the precise computation of results involving multiple scattering. To validate the accuracy of the algorithm, we compared the simulated results with the theoretical values of the visible light scattering intensity from a Lambertian sphere. The relative error obtained was 0.8%. Subsequently, a complex scene of engineering vehicles and grass was established. The results of different observation angles and different coating materials were calculated and analyzed. In summary, the algorithm presented in this paper has the following advantages. Firstly, it is applicable to geometric models composed of any triangular mesh elements and accurately computes the effects of multiple scattering. Secondly, the algorithm combines the spectral BRDF information of materials and improves the efficiency of multiple scattering calculations using nonuniform sampling. The computed hyperspectral scattering data can be applied to simulate airborne or space-borne remote sensing data.
Journal Article
Research on the Ionospheric Delay of Long-Range Short-Wave Propagation Based on a Regression Analysis
The ionospheric delay effect is inevitable when a radio signal propagates through the ionosphere. It has been extensively studied in the L-band. Typically, the influence of the ionosphere on the code phase and carrier phase is regarded as the same. In this study, a numerical ratio between the group delay time and phase advance time with reference to the study of the L-band is investigated in the short-wave band. The variation in the numerical ratio with frequency, critical frequency, and elevation angle is discussed in detail. There appears an interesting phenomenon wherein the elevation angle has a greater effect on the ratio than the frequency and critical frequency. The numerical ratio increases with an increasing elevation angle. On the other hand, a regression analysis is used to establish the mapping relation between the ratio and the three factors of frequency, critical frequency, and elevation angle, based on the simulation results obtained by a ray-tracing algorithm. The little relative errors between the fitted values and simulation values under different ionospheric models prove the relationship between the ratio and the three factors of frequency, critical frequency, and elevation angle.
Journal Article
A fast piecewise 3D ray tracing algorithm for determining slant total delays
Due to high computation demand, slant total delays (STDs) determined by 3D ray tracing cannot be widely used in geodetic analysis. This study proposes a novel fast 3D ray tracing approach, named APM-3D, based on piecewise algorithm and strictly matched step size. It can produce more than 1000 rays per second with a single core PC, which satisfies the operational applications of slant delays in mapping function establishment and other areas. Comparisons have shown mm-level agreement in slant delays at 5° elevation angle between APM-3D and several algorithms presented by different institutes in a comparison campaign. APM-3D also exhibits better stability than the standard RK4 method. Further validation using a 3D ray tracing based on the Cartesian coordinate system and 2D ray tracing also indicates excellent agreement, while constant differences in geometric delays between 3 and 2D exist under complex weather conditions. With ERA5 reanalysis data, the characteristics of STD evolution are presented during a rainstorm that occurred on July 1–2, 2020, over Wuhan.
Journal Article
The expression of multimedia animation art design in the era of artificial intelligence
Aesthetic rules are the basis of animation art design, combined with the user-centered design method is a new form of multimedia animation art design. This paper combines the existing three-dimensional animation art forms of expression, the use of points, lines, and surfaces to generate three-dimensional animation three-dimensional space, and selected virtual reality technology to achieve three-dimensional animation conversion. Based on ray tracing algorithm and radiance global illumination technology, to optimize animation scene realism, analyze the difficulties of rendering image styles. Combined with the Canny edge extraction algorithm to extract the target area contour, homogenization processing of local area coloring, fusion of the extracted contour and coloring area, the formation of animation style rendering, constituting the design of this paper three-dimensional animation art design expression. Analyze the rendering data of trees in a typical natural scene and use design evaluation indexes to assess the performance impact of animation scene art design. The average score for the animation scene expressing information content, the average score for the animation matching with the information, and the average score for the animation effect art and beauty are 7.672, 7.027, and 7.474, respectively. The scores indicate that the animation art design expression proposed in this paper can provide a more accurate depiction of the aesthetics of animation art.
Journal Article
Numerical Evaluation on the Thermal Performance of the Solar External Cylinder Receiver using Monte Carlo Ray-Tracing Algorithm
The heat receiver is an essential part of the Concentrating Solar Power plant, directly affecting its operation and safety. In this paper, the Monte Carlo ray-tracing algorithm was introduced to evaluate a 50 MW (e) external cylindrical receiver’s thermal performance. The radiation heat flux concentrated from the heliostats field and the view factors between grids divided from the tubes were both calculated using Monte Carlo ray-tracing algorithm. Besides, an in-house code was developed and verified, including three modules of the view-factor calculation, thermal performance calculation, and thermal stress calculation. It was also employed to investigate the 50 MW (e) receiver, and the detailed 3D profiles of temperature and thermal stress in the receiver were analyzed. It was found that the molten salt was heated from 298°C to 565°C and the tube at the 50 MW (e) receiver’s outlet had a high temperature, while the high thermal stress came out at the receiver’s entrance. Finally, the over-temperature of the receiver was discussed, and an optimization algorithm was introduced. The tube wall temperature and film temperature at the overheated area matched the safety criteria, and the outlet molten salt temperature still reached 563°C after the optimization process, with only 2°C dropped.
Journal Article