散景效果的真实感绘制

针对现有方法绘制的散景效果真实感较差的问题,提出一种基于几何光学理论的散景效果真实感绘制方法.该方法以光线传播的折射定律为基础,利用序列光线追踪方法对相机镜头的光学成像特性进行精确建模;对相机镜头的内部结构进行精确模拟,包括孔径光阑和渐晕光阑,以绘制出由孔径形状和渐晕共同作用的散景效果;利用几何光学理论和序列光线追踪方法精确计算出出射光瞳的位置和大小,以辅助光线采样,提高光线追踪效率.绘制结果表明,利用该方法能够绘制出较为逼真的散景效果,正确模拟了孔径形状和渐晕对散景效果的影响,并具有较高的光线追踪效率.     

景深效果绘制技术综述

景深效果能够增强计算机生成图像的真实感,因此关于这类效果的绘制已成为计算机图形学中的重要研究方向。针对景深效果的绘制问题,首先研究和分析各种相机镜头模型的光学成像原理,比较各类镜头模型的特点和模拟景深效果的能力;然后分类总结景深效果绘制的基本原理和典型算法,比较各类景深绘制方法的优缺点。最后指出景深效果绘制技术的应用价值,并展望未来的研究方向。     

3D靶标的摄像机三步标定算法与实现

摄像机标定是计算机视觉中的一个必不可少的重要环节,其标定精度影响着三维重建结果的精度。利用摄像机对一个三维正交的棋盘格拍摄一幅有效靶标图像,提取角点,第一步通过透视变换矩阵算法线性求解各内外参数;第二步引入径向和切向畸变,将第一步求得的内外参数作为初始值,求得畸变系数的解;第三步对内参数进行线性优化,得到更为精确的内参数值;最后求解反投影后图像坐标的绝对误差。实验结果表明,该方法具有较高的精度,且简单有效。     

基于灭点理论和平面控制场的相机标定方法研究

给出了一种基于灭点理论和平面控制场的相机解析自标定方法。在系统分析平面场景灭点几何的基础上,依据灭点理论并结合2维场景的共线方程严密论证和推导了平面控制场中相机外方位元素初值的实用算法。给出了一种圆形标志点的快速检测及定位方法,提出了一种基于计算可靠性矩阵QVVP的自检校光束法平差中各类观测值权值的确定方法。实验证明了该相机标定方法的正确性和有效性,为相机标定探索了一种可行的方法。     

自动化几何校正中相机位姿自动校正方法

为了解决多投影仪拼接显示系统自动几何校正中相机位姿的自动校正问题,提出了一种利用目标区域角点集的最小外接矩形确定目标的倾斜状态的方法。首先运用Harris角点检测算子检测出目标区域的角点集,并根据角点集的凸包求其最小外接矩形,然后计算最小外接矩形的长或宽的斜率判断出目标区域的倾斜状态,最后结合云台的控制,对相机姿态做出实时调整,实现了自动几何校正工作中相机位姿的自动校正功能。     

The Visual Computing of Projector‐Camera Systems

This article focuses on real‐time image correction techniques that enable projector‐camera systems to display images onto screens that are not optimized for projections, such as geometrically complex, coloured and textured surfaces. It reviews hardware‐accelerated methods like pixel‐precise geometric warping, radiometric compensation, multi‐focal projection and the correction of general light modulation effects. Online and offline calibration as well as invisible coding methods are explained. Novel attempts in super‐resolution, high‐dynamic range and high‐speed projection are discussed. These techniques open a variety of new applications for projection displays. Some of them will also be presented in this report.     

Camera Control in Computer Graphics

Recent progress in modelling, animation and rendering means that rich, high fidelity virtual worlds are found in many interactive graphics applications. However, the viewer's experience of a 3D world is dependent on the nature of the virtual cinematography, in particular, the camera position, orientation and motion in relation to the elements of the scene and the action. Camera control encompasses viewpoint computation, motion planning and editing. We present a range of computer graphics applications and draw on insights from cinematographic practice in identifying their different requirements with regard to camera control. The nature of the camera control problem varies depending on these requirements, which range from augmented manual control (semi‐automatic) in interactive applications, to fully automated approaches. We review the full range of solution techniques from constraint‐based to optimization‐based approaches, and conclude with an examination of occlusion management and expressiveness in the context of declarative approaches to camera control.     

单目变焦摄像机自运动的标定测量法

为了在单目摄像机变焦情况下测量其自运动参数,提出一种单目变焦摄像机自运动的参数标定测量法。在飞行平台着陆过程中,固连其上的单目俯视摄像机对包含已知世界坐标的特征点的静态着陆平面进行连续拍摄,该方法利用单帧图像可解算得到摄像机拍摄当时的等效焦距及其相对于着陆平面的6自由度位置,结合多帧信息即可对摄像机自运动的运动速度进行估计,进而转换为飞行平台的着陆运动参数。实验结果证明该方法可行有效。     

Repair approach for DMC images based on hierarchical location using edge curve

The color composite digital mapping camera (DMC) images are produced by the post-processing software of Z/I imaging. But the failure of radiometric correction in post-processing leads to residual radiometric differences between CCD images, which then affect the quality of the images in further applications. This paper, via analyzing the characters and causes of such a phenomenon, proposes a repair approach based on hierarchical location using edge curve. The approach employs a hierarchical strategy to locate the transition area and seam-line automatically and then repair the image through the global reconstruction between CCD images and the local reconstruction in the transition area. Experiments indicate that the approach proposed by this paper is feasible and can improve the quality of images effectively. Supported by the National Basic Research Program of China (Grant No. 2006CB701302) and the Youth Fundation Plan of Wuhan (Grant No. 200750731253)     

基于P89C668单片机的航空数码相机控制系统

以 P89C668 单片机为核心,介绍了一种自主开发的航空数码相机的控制系统,合理利用单片机的固有资源,相互配合完成了相机镜头控制:光圈控制,快门控制;数据异步通讯:开关命令的采集和拍摄状态信息的回传;PC 方式对 CCD 驱动单元配置等多项功能,并编写了相应的控制软件.控制系统模块设计清晰,工作稳定可靠,成功的以单片微型计算机实现了航空相机多项控制功能的要求,为系统功能的进一步开发提供了充足的硬件资源和软件平台,是一个实用的航空数码相机控制系统.