レイ・トレーシング法におけるマッピングの応用について : コンピュータによる建築パースに関する研究(2)

In today’s workplace, the personal computer and spreadsheet have become commonplace, while lens design software, often costing more than the computer, is not. Any one of the generic spreadsheet programs can be an effective ray tracing tool. Anyone who has developed ray tracing software has found that the input/output problem can often be more difficult than the algorithms for ray tracing. The advancement in today’s spreadsheets has eliminated the need for sophisticated programming skills to produce usable ray tracing functions. The worksheet developed combines third-order ray tracing with aproximate polarization equations. Useful graphic functions can be developed for displaying the third-order surface contributions and the polarization change for each surface. Examples of the macros developed are shown. A demonstration of a double Gauss ray trace is given. These macros can also be a useful tool for those with high powered lens design software. The macros are designed so that a lens can be set up in the spreadsheet and used as the input to commercially available lens design software.

In order to better display and protect ancient Chinese architecture, a three-dimensional model reconstruction method based on multi-station laser scanning is proposed. This method mainly includes several steps, such as point cloud data collection, preconditioning, multi-site cloud data fusion, point cloud data compression, 3D model reconstruction and texture mapping, environment rendering, video processing, and 3D roaming. According to the requirement of video rendering and virtual roaming, we focus on cloud processing, 3D modeling and 3D model display in this paper. Experimental results show that an famous building named Enshi Dong Drum Tower is well digitally reconstructed, so as to result in ethnic characteristics and cultural heritage protection in practical application.

Differing from common 2D images, a texture map, since it is used to project onto a 3D model in 3D space, not only contains 2D texture information, but also implicitly associates certain 3D geometric information. Related to this, an effective 3D geometry-dependent texture map compression method with hybrid region of interest (ROI) coding is proposed in this paper. We regard the visually important area of the texture map as the ROI. To acquire the visually important areas of the texture map, we take into account information from both the 3D geometry and 2D texture maps, depicting the saliency of the textured model, distortion of the texture mapping, and boundary of the texture atlas. These visually important areas are expressed as a visual importance map. According to the particularity of the texture map, a hybrid ROI coding method that utilizes Max-Shift and an improved post compression rate distortion (PCRD) technique is presented, guided by this visual importance map. To find the exact wavelet coefficients pertaining to these ROIs before carrying out the hybrid ROI coding, this paper proposes a stochastic coefficient priority mask map computational method. Experimental results show that the visually important areas of the texture image have a better visual effect and that a good rendering result can be obtained from the texture mapping.

Introduction: According to Piaget, children and adolescents pay more attention to films presenting novel and eccentric pictures, different from those of their normal daily life. This research aims at studying the influence of special effects in educational films on learning amount. Methods: In this study, using random cluster sampling method, from among 1777 fourth-graders in state elementary schools in Shahroud, eight classes (250 pupils), and from the practical sciences textbook, four chapters were selected. Eight content-relevant films with and without special effects were also produced. Having displayed the films, the researchers administered a post test including g20 questions (five items for each chapter). The results were analyzed using an independent t-test procedure in boy and girl groups. Results: The results indicated that the mean score of the boys who had seen the films with special effects was 3.64 and that of the boys having seen films with no special effect was 3.65 which do not show any significant difference. However, the mean score of the girls who had seen the films with special effects was 3.52 and that of the girls having seen films with no special effect was 3.29 which shows a significant difference. Conclusion: Creating attractive spaces in films is possible with the aid of special effect techniques, the simplest of which are picture effects such as dissolve, feed and superimpose. These techniques are even simply available on personal computers. Nowadays, computer has changed the society and the learning processes for ever. This study confirms the role of gender in the effectiveness of films with special effects. This fact indicates higher level of excitation in boys, due to their more exposure to computer games and action films.

A compression scheme for calibrated images depicting a static scene from arbitrary viewpoints is presented. 3D scene geometry is reconstructed, and view-dependent texture maps are generated from all images. Texture is wavelet-coded using the SPIHT coding scheme extended to 4D, exploiting correlations within as well as between texture maps. During decoding, all texture maps are simultaneously and progressively reconstructed. The coder provides 3D scene geometry and multiple texture maps, enabling the use of graphics hardware to accelerate the rendering process. Three image sets acquired from real-world objects are used to evaluate the model-based coding scheme. Coding efficiency is shown for geometry approximations of different accuracy.

High-fidelity simulation is a key enabling technology for the widespread deployment of large unmanned ground vehicles (UGVs). However, current approaches for lidar simulation leave much to be desired, particularly for scenes with vegetation. We introduce a novel 3D mapping technique that learns high-fidelity models for geo-specific lidar simulation directly from pose tagged lidar data. We introduce a novel stochastic, volumetric model that captures and can reproduce the statistical interactions of lidar with terrain. We show how to automatically learn the model directly from 3D mapping data collected by a UGV in the target environment. We extend our approach using terrain-classification techniques to develop a hybrid surface–volumetric model that combines the efficiency of surface modeling for areas that are well approximated by large surfaces (e.g. roads, bare earth) with our volumetric approach for more complex areas (e.g. bushes, trees) without sacrificing overall fidelity. We quantitatively compare the performance of our approach against more conventional methods on large outdoor datasets from urban and off-road environments. Our results show significant performance gains using our volumetric and hybrid approaches over the state-of-the-art, laying the ground work for truly high-fidelity simulation engines for UGVs.

This paper proposes a new 3D gas distribution mapping technique based on Gaussian belief propagation, which is capable of resolving in real time, the concentration estimates in 3D space whilst accounting for the obstacle information within the scenario, the first of its kind in the literature. The gas mapping problem is formulated as a 3D factor graph of Gaussian potentials, the connections of which are conditioned on local occupancy values. The Gaussian belief propagation framework is introduced as the solver and a new hybrid message scheduler is introduced to increase the rate of convergence. The factor graph problem is then redesigned as a dynamically expanding inference task, coupling the information of consecutive gas measurements with local spatial structure obtained by the robot. The proposed algorithm is compared to the state of the art methods in 2D and 3D simulations and is found to resolve distribution maps orders of magnitude quicker than typical direct solvers. The proposed framework is then deployed onboard a ground robot in a 3D mapping and exploration task. The system is shown to be able to resolve multiple sensor inputs and output high resolution 3D gas distribution maps in a GPS denied cluttered scenario in real time. This online inference of complicated gas dispersion provides a new layer of contextual information over its 2D counterparts and enables autonomous systems to take advantage of real time estimates to inform potential next best sampling locations. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The motivation of this work arises from the need to develop the robotic gas distribution mapping capability that can provide real-time situational awareness of the scenarios. The output distribution maps can be used to inform human first responders as to what areas of the environment contain a hazard, but looking towards autonomous robots, they can also be used by the robot itself to inform where should be measured next to gather more information about the environment. When performing these mapping tasks in unknown indoor environments, it is very important that the sensing robot can build up the knowledge of its physical surroundings together with how the obstacles in the environment affect the 3D gas distribution. The Gaussian belief propagation algorithm allows us to achieve all of this in real-time onboard the sensing robot, something that is yet to be achieved in the literature.

This paper presents the results of experiment-based simulation aimed at analyzing the harmonic distortion behavior of nonlinear loads and the background voltage distortion of power supply in building low-voltage (LV) distribution network. The procedure of constructing experiment-based simulation model and harmonic monitoring at various points of common coupling (PCCs) in LV network are introduced for analyzing voltage and current harmonic distortion behavior due to attenuation effect. The model is proposed for future microgrid modeling analysis at different PCCs in LV networks. The simulation model was constructed from captured harmonic data and the corresponding LV network topology. The simulation model has been verified by comparing with field measurement results. The VTHD and ITHD relationship curve and the attenuation effect curve for personal computers (PC) have been proposed by using the simulation model. In particular case study has been conducted to compare the conventional and state-of-art switch mode power supply (SMPS) used in PCs.

Environment maps, like texture maps or any other maps consisting of discretely stored data have to be properly filtered, if they are being resampled in the process of rendering an image. For environment maps, this is especially important, as the sampling rate is subject to extreme changes due to the curvature of the reflecting surfaces. However, for the same reason, the antialiasing is especially difficult to perform, as the sampling rate has to be determined for each pixel. We introduce a method to perform this calculation and determine the parameters for anisotropic filtering of the environment map. Instead of the BRDF, we employ roughness pyramids to account for the properties of the reflecting surface. The principles that are used to perform this antialiasing can be applied for antialiasing reflected textures in general e.g. in ray tracing.

The aim of this thesis is to use a three-dimensional (3D) architectural plant modelling approach to simulate possible ways to improve the aboveground competitive ability of chickpea (Cicer arietinum L.) with sowthistle (Sonchus oleraceus L.). It is now widely accepted that the best approach to manage weeds in field crops is through the development and implementation of integrated weed management (IWM) approaches. Such approaches should make use of the competitive ability of the crop canopy and the application of other cultural practices that ultimately reduce the dependence on herbicide use. To help understand the complexity of the different IWM choices available, computational models can be used by the agronomist, plant breeder or agricultural practitioner to simulate and visualise these different cultural practices in weedy situations to evaluate the possible ways to enhance crop competitiveness to the common weeds of that crop. In order to demonstrate the feasibility and value of such an approach, research experiments and modelling techniques have been used to develop architectural models for chickpea and sowthistle. These models were then used to simulate how changes in crop canopy architecture could modify chickpea’s competitive ability with sowthistle. In order to determine the potential of using canopy manipulations of the crop to improve its competitive ability with sowthistle, an experiment was conducted in which sowthistle plants were grown under two densities of chickpea and in full sun light (as a control). While the phyllochron and bolting time of sowthistle increased when the light availability decreased, the number of branches, number of capitula and consequently seeds in sowthistle were significantly decreased under reduced light availability. To capture the 3D architecture of the chickpea and sowthistle, plants were grown separately in a sandy, well watered and fertilized soil. A sonic digitizer system was then used to record a number of chenges in plant morphological, topological, and geometrical changes in a non-destructive way over time. The resulting data sets were analysed and used to develop a realistic, dynamic architectural model for each of the two species. Plant architectural (virtual) models were created using the mathematical formalism of Lindenmayer Systems. The virtual plant models were verified for growth and development, using an independently produced data set. A quasi-Monte Carlo ray tracing program was employed to estimate the light availability under different architectures of the virtual chickpea plants in a “chickpea-light environment” model. Since the aim was to simulate the effect of the chickpea canopy manipulation on sowthistle morphogenesis, observation of the effect of light availability on sowthistle were used to calibrate the morphogenesis of virtual sowthistle and then this lightsensitive virtual sowthistle was incorporated into the chickpea-light environment model. The key point is that the entire development period and changing light environment is considered. In the final ‘chickpea-light environment-sowthistle’ (CLES) model the virtual chickpea plants were modified to replicate the architecture of five different cultivars (Macarena, Bumper, Jimbour, 99071-1001, and 96033-1014). The models were run over time and both visualizations and numerical output were produced to examine their competitive ability with sowthistle. To validate the results of the CLES model, an experiment using the same five chickpea cultivars with a sowthistle growing under their canopy was conducted. The simulation results were found to be in good agreement with the empirical data. The growth of sowthistle, in both in silico and empirical experiments was reduced most by 99071-1001 a cultivar with short phyllochron and early branching feature. The second rank of competitive ability in both simulated and observed data belonged to Macarena and Bumper while Jimbour and 96033-1014 were the least competitive. Both the simulation and experiment results supported the hypothesis that morphogenesis of a weed can be suppressed under specific canopy architectures of crops. Some practical applications of the developed model are discussed and it is shown that the developed model can be used to explore a number of different agronomic practices such as choice of cultivar and seeding rate in weed management systems. The practical implication of these simulation studies is how a management system that uses quick canopy closure can provide sufficient suppression of weeds in chickpea. The study also demonstrates the versatility of the 3D plant architectural modelling approach especially when combined with a light environment model to predict how the plant breeder might genetically improve the crop canopy architecture and how the agronomist might modify planting rules, to improve the competitive ability of crops with weeds.

The thesis investigates a way to perform realistic three-dimensional texturing of ray-traced objects that is especially useful for objects with irregular surfaces. Two similar existing methods are texture mapping and particle systems. The thesis describes these methods and points out their strengths and weaknesses. It then proposes an alternative to these methods that uses a construct called a lattice. Lattices make as fast ray tracers, but they are inexact. As long as lattices are used for small objects, though, their inexactness doesn't show on the scale of the display, and the result is acceptable. The thesis also shows how lattices fit with the more traditional largescale ray tracer, combining lattices with a Constructive Solid Geometry (CSG) object model to pr?duce several examples. . Time and memory space considerations are major constraints on lattices. The thesis discusses these limitations and how they can be reduced.

International Reference Ionosphere and ray tracing algorithm are discussed in the paper. Three-dimensional real-time ray tracing method is illustrated In accordance with International Reference Ionosphere, ray tracing equations are resolved by Runge-Kutta method. Based on International Reference Ionosphere and ray tracing algorithm, the three-dimensional ray tracing simulation software is presented. The three-dimensional ray trace and the group path are estimated by the simulation software. The effectiveness and accuracy of the simulation results are verified by comparing with the experimental results.

Ray tracing is a frequently used method for acoustic simulations, valued for its calculation speed and ease of use. Although it is fast, there are no fully ray tracing-based real-time simulation methods or engines. Under real-time restrictions, ray tracing simulations lose precision and the variance inherent in the random simulation method has too much impact on the outcome. In this paper, an algorithm called iterative ray tracing is presented that reduces the negative effects of real-time restrictions by iteratively improving the initial calculation and increasing the precision over time. In addition, new estimates of the expected value and variance of ray tracing simulations are presented and used to show the iteration steps in the new algorithm reduce variance, while maintaining the expected value. Simulations using iterative ray tracing are compared to measurements and simulations using the classical ray tracing method, and it is shown that iterative ray tracing can be used to improve precision over time. Although more testing is needed, iterative ray tracing can be used to extend most ray tracing algorithms, in order to decrease the adverse effects of real-time restrictions.

Hardware support for image processing is very important in emerging applications such as desktop publishing, medical imaging, and multimedia. In the past, computational needs for intensive image processing tasks, such as image analysis of satellite data and pattern recognition, were satisfied with custom, complex, and expensive image processing architectures [1], [2] However, the latest scientific workstations have enough compute power for low-cost desktop image processing. Furthermore, traditional image processing operations, such as texture mapping and warping, are now combined with conventional graphics techniques. Hence, there is an increased interest for accelerated image and video processing on low cost computational platforms, such as personal computers and scientific workstations.

We proposed a texture mapping technique that comprises mesh partitioning, mesh parameterization and packing, texture transferring, and texture correction and optimization for generating a high-quality texture map of a three-dimensional (3D) model for applications in e-commerce presentations. The main problems in texture mapping are that the texture resolution is generally worse than in the original images and considerable photo inconsistency exists at the transition of different image sources. To improve the texture resolution, we employed an oriented boundary box method for placing mesh islands on the parametric (UV) map. We also provided a texture size that can keep the texture resolution of the 3D textured model similar to that of the object images. To improve the photo inconsistency problem, we employed a method to detect and overcome the missing color that might exist on a texture map. We also proposed a blending process to minimize the transition error caused by different image sources. Thus, a high-quality 3D textured model can be obtained by applying this series of processes for presentations in e-commerce.