虚拟地球场景的可视化建模与仿真

从地球自身模型出发,提出了按季风带划分大气云层实现其转动的新方法。为了提高拟真性,探讨了大气散射的成因,研究了大气散射算法并通过GPU编程实现,最后给出了基于多重纹理混合映射的星空背景模型。实验结果表明,这些方法可以大幅提高整个场景的拟真度,同时具备高实时性。可以被广泛地用于空间作战、探测等仿真任务。

Abstract：

Starting from the earth model,a new method was proposed that the rotation of atmospheric could be divided by monsoon belt.In order to improve the fidelity,the reason caused atmospheric scattering was investigated,and the scattering algorithm was studied and implemented by GPU programming.At the end,the star scene model based on multiple texture blending was given.The result of experiment shows that these methods have not only given a substantial increase in fidelity,but also guaranteed real-time rendering.It can be widely used in simulation of space battlefield and exploration.     

Bidirectional Texture Mapping

Texture mapping is an important technique for high -quality image generation in computer graphics. In this paper, the shortcoming of the traditional texture mapping approaches is analysed and a general bidirectional texture mapping method is proposed. Based on the bidirectional mapping, an algorithm for mapping an image to an arbitrary polygon in 3D space is given.     

Solving multi-object radar cross section based on wide-angle parabolic equation method

1. INTRODUCTION The parabolic equation (PE) was first introduced to treat the problems of diffraction of radio waves around the earth by Leontovich and Fock[1,2]. It’s a full-wave technique based on splitting the wave equation into two parabolic equations: outgoing and incoming parabolic wave equation, which describes the forward and backward propagating fields. The solution is marched from plane to plane along some preferred direction (say, paraxial direction). This technique reduces t…     

Project Systems Engineering for Developing Space Robots

Space robots possess unique distinguishing features unlike general robots on earth, due to the particular environments in space. The developing of various practical space robots promoting the improvement of space science and technology is a complex man-machine-environment engineering problem. This paper analyses from the systems engineering viewpoint the space robot system in the scope of the architecture of robotics discipline, space environment characteristics, man-machine-environment system of space robots, the general methodology of project systems engineering and the process of space robot systems engineering.     

Progress in Space Microelectronics

Research and development work of space microelectronics of China startedin 1965 as part of the space development program of China. Jointcoordination administered by the Ministry of Aero-Space results in success of China's first generation of space program including the launching ofcommunication satellite. It is to be emphasized that during this phase of Rand D for space microelectronics (1965～1978), we were completely iso-     

Image decomposition using adaptive regularization and div （BMO）

In order to avoid staircasing effect and preserve small scale texture information for the classical total variation regularization, a new minimization energy functional model for image decomposition is proposed. Firstly, an adaptive regularization based on the local feature of images is introduced to substitute total variational regularization. The oscillatory component containing texture and/or noise is modeled in generalized function space div (BMO). And then, the existence and uniqueness of the minimizer for proposed model are proved. Finally, the gradient descent flow of the Euler-Lagrange equations for the new model is numerically implemented by using a finite difference method. Experiments show that the proposed model is very robust to noise, and the staircasing effect is avoided efficiently, while edges and textures are well remained.     

COMBINING SINGULAR SPECTRUM ANALYSIS AND PAR（p） STRUCTURES TO MODEL WIND SPEED TIME SERIES

Singular spectrum analysis （SSA） is a technique that decomposes a time series into a set of components, such as, trend, harmonics, and residuals. Leaving out the residual components and adding up the others, the time series can be smoothed. This procedure has been used to model Brazilian electricity consumption and flow series. The PAR（p）, periodic autoregressive models, has been broadly used in modelling energy series in Brazil. This paper presents an approach of this decomposition method, by fitting the PAR（p）, considering its multivariate version known as multivariate SSA （MSSA）. The method was applied to a vector of two wind speed series recorded at two locations in the Brazilian Northeast region. The obtained results, when compared to the univariate decomposition of each series, were far superior, showing that the spatial correlation between the two series were considered by MSSA decomposition stage.     

Image completion algorithm based on texture synthesis

A new algorithm is proposed for completing the missing parts caused by the removal of foreground or background elements from an image of natural scenery in a visually plausible way. The major contributions of the proposed algorithm are: (1) for most natural images, there is a strong orientation of texture or color distribution. So a method is introduced to compute the main direction of the texture and complete the image by limiting the search to one direction to carry out image completion quite fast; (2) there exists a synthesis ordering for image completion. The searching order of the patches is defined to ensure the regions with more known information and the structures should be completed before filling in other regions; (3) to improve the visual effect of texture synthesis, an adaptive scheme is presented to determine the size of the template window for capturing the features of various scales. A number of examples are given to demonstrate the effectiveness of the proposed algorithm.     

Hybrid algorithm for project scheduling with capacity constraint

Motivated by the projects constrained by space capacity and resource transporting time, a project scheduling probIem with capacity constraint was modeled. A hybrid algorithm is proposed, which uses the ideas of bi-level scheduling and project decomposition technology, and the genetic algorithm and tabu search is combined. Topological reordering technology is used to improve the efficiency of evaluation. Simulation results show the proposed algorithm can obtain satisfied scheduling results in acceptable time.     

基于纹理传输的烙画风格图像仿真

针对基于图像生成的烙画艺术问题,以纹理合成与传输算法为基础,提出了一种基于纹理传输的烙画风格图像仿真算法。利用YCbCr颜色空间中亮度直方图的相似性匹配,实现了纹理传输过程中误差优化,避免了局部纹理块的拷贝错位,最后通过对传输结果图像与背景图像的加权控制完成图像融合。仿真实验表明,该方法生成的仿真图像接近真实烙画视觉效果。

Abstract：

Aiming at solving the problem with the image-based pyrography generation,a novel style of pyrography painting simulation algorithm was proposed based on texture synthesis and transfer.It is suggested that the brightness histogram matching in YCbCr color space be adopted to optimize errors during the image processing,the texture block copy be reoriented correctly,and ultimately the image fusion be achieved through weighted control.Experimental results show that a very similar-to-real pyrography simulation effect can be achieved through this approach.     

地球云场景的模拟仿真

为了研究全球的大气运动情况,需要不断观察地球云层的分布状态和运动趋势。运用计算机技术建立了基于八面体剖分法构造的球面网格模型;以全球高程数据为基础进行了三维地球的模拟;利用改进的分形几何算法生成了逼真的静态与动态云图;通过球面纹理映射实现了云场景在球面上的融合;最终给出了逼真的全球云场景的模拟。仿真模拟算法在虚拟战场环境模拟和全球气象环境再现等软件中进行了应用,模拟仿真效果满足了系统的需要。     

两步纹理映射的改进算法

两步纹理映射方法将映射过程分解为S映射与O映射两步进行。由于传统的S映射算法难以使纹理在中介面上保持连续，真实感效果不能令人满意。将中介面划分为对称的两部分，同时将纹理图案分割为两块，采用面积等出约束的对称映射算法将两块纹理映射到中介面两部分；运用加权插值技术对纹理接缝区域进行平滑处理，实现纹理的无缝拼接，进一步通过O映射，所生成的纹理能够在物体的所有表面都保持连续，具有较小的变形。     

航天视景仿真特殊效果图形生成技术

深入分析了航天视景仿真中火、云、烟、雾霾等特殊效果图形生成三种通用的方法;纹理映射、粒子系统、分形图像生成,并对其进行详细的比较分析,此外还进一步介绍了纹理映射中采用的Billboarding和体绘制技术。     

双向纹理映射

在计算机图形学中,纹理映射是高质量图像生成技术中的一个重要内容,本文分析了传统的纹理映射方法的不足之处,提出了一种通用的双向纹理映射方法。并且,根据双向映射的思想,给出了一幅图像映射到三维空间任意平面多边形上的映射算法。     

基于Perlin噪音绘制云的方法

天空中的云对于构造逼真的室外虚拟环境是必不可少的。如何对云进行建模和绘制是计算机图形学研究的热点问题。本文首先详细介绍了Perlin噪音的概念和生成方法，并以此为基础绘制出3D云的图像；然后论述了使用所绘制的云的图像，运用基于图像的绘制技术在3D虚拟环境中实时绘制云的方法，我们生成的云的位置和方向能够随用户漫游时视点的变化而变化。     

纳卫星轨道热环境仿真分析

轨道热环境分析对于纳卫星热控系统的设计与仿真研究具有重要意义。针对进行纳卫星轨道热环境分析的关键问题,通过详细的数学分析,建立起计算简单、便于应用的纳卫星本体质心坐标系内的太阳向量、地球向量的仿真计算模型,以及外热流分析所必需的其它时变空间几何参数的计算方法,满足了纳卫星热控系统的在轨仿真计算中快速、简便的进行太阳辐照、地球辐照、地球反照等外热流计算的客观需要,进而应用上述模型和方法对一椭圆轨道近地空间探测纳米卫星的轨道热环境进行了仿真计算,并对其结果进行了详细的分析与讨论。     

近地空间环境要素三维建模与可视化仿真研究

提出了近地空间环境要素三维建模的静态模型和实测模型。根据近地空间环境各要素的特点，首先利用各种静态模式和实测数据构建三维空间数据场。然后对数据场进行六面体单元剖分，其中对实测得到的空间数据利用雅克比矩阵转换为规则六面体数据。最终，分别给出了中性大气、电离层等离子体、地球基本磁场和地球辐射带的几何模型，提出了一种适合于近地空间环境要素仿真的通用三维可视化方案。     

基于改进IBFV的矢量场剖面纹理可视化

通过分析经典IBFV方法可视化效果差的原因,提出改进方法:在IBFV过程中使用相关性较高的背景纹理图像。该背景纹理使用GLSL由GPU加速的多重线积分卷积生成。研究了将三维矢量场投影到二维图像空间的方法;利用GPU的顶点颜色插值功能,将离散矢量场转换为连续的纹理数据场,以便于使用GPU完成线积分卷积运算。在算法实现过程中,研究各参数对显示结果的影响,找出合适的取值。通过以上分析和研究,相比于IBFV改进的算法的可视化效果将得到显著提高。