基于等距序列图像的快速拼接技术

针对工程领域中经常需要采集多幅序列数字化图像，并将序列图像进行快速精确拼接、实时显示的需求，提出了一种基于等距序列图像快速拼接方法和数学模型。其利用图像匹配算法确定初始拼接点位置，采用精密光栅作为定位元件，准确测定拼接点位置，并获得等距序列图像，并利用所提出的数学模型可对序列图像进行一次性快速拼接。同时，在激光干涉仪上验证了数学模型，结果表明，提出的方法和模型在满足图像拼接精度的前提下，可大幅度提高拼接速度。     

一种基于整体平差的图像拼接方法

提出了一种基于整体平差的栅格图像拼接方法，该方法把整幅图纸的４个角点作为拼接控制点，然后利用相邻扫描图像块重叠区中连接点的传递特性，通过量测与整体平差，算得各扫描图像块相对于图幅坐标系的几何变换参数，最后经重采样实现图像的自动拼接，所列试验表明，新提出的拼接方法速度快、精度高。     

内河船舶安全系统中的红外图像拼接

提出了一种较适合红外图像的拼接算法．该算法根据红外成像特点,通过对相邻2幅序列图像差值图像极值点的搜寻,快速提取2幅序列图像之间的重叠部分,并采用线性加权法得到无缝拼接的图像,可提高红外热成像仪在船舶安全中的可用性．     

一种基于特征区域分割的图像拼接算法

针对图像采集和测量时需要将多幅图像拼接成一幅大图像的问题，提出了一种图像拼接算法，利用特征区域块分割技术来实现图像的拼接。用灰阶Sobel算子通过引入衰减因子对图像进行边缘检测得到不失真的灰阶边缘图，然后将灰阶边缘图进行三次样条插值处理，使特征区域块边缘的定位达到亚像素级，提高了图像边缘检测的精度，有利于图像的高精度拼接。实践结果表明，该算法简单易行，定位较准确，拼接效果好，能有效地克服图像质量的影响，当图像灰度值相差较大并且图像具有旋转时，该算法也能实现对图像无缝平滑拼接。     

全景图拼接算法的设计与实现

研究了全景图生成过程中相关图片拼接的问题．探讨了通常的2种图像拼接算法及其优缺点，在定义匹配图、包含图和模板图的基础上，提出了一个基于模板匹配的全景图拼接算法，引入标准相似度实现模板匹配，在Visual C＋＋6．0环境中编程实现图片的拼接，并验证了算法的正确性．     

基于SURF特征相关的红外图像自动拼接

提出一种鲁棒性较好的图像拼接算法解决红外图像序列的自动拼接问题。首先应用图像子区域相位相关得到图像间近似重合子区域和图像间近似仿射变换参数;接着根据得到的参数值对SURF特征计算和特征匹配进行优化,提高了图像配准速度;然后以特征点对的对称投影位置误差最小化为目标,应用RANSAC和LM算法对图像间透视变换矩阵进行优化;最后应用得到的透视变换建立图像序列整体配准关系,并采用线性过渡法进行重叠区域融合得到最终的拼接图像。     

面阵CCD内窥定位测量中的图像扫描拼接方法及其精度分析

介绍了采用面阵ＣＣＤ的管孔内窥定位测量中的两种图像扫描和拼接方法，给出了其图像拼接方程；并在对其图像拼接精度进行分析的基础上，指出了影响图像拼接精度的主要因素．     

面阵CCD内窥定位事的图像扫描拼接方法及其精度分析

介绍了采用面阵ＣＣＤ的管孔内窥定位测量中的两种图像扫描和拼接方法。给出了其图像拼接方程，并在对其图像拼接精度进行分析的基础上，指出了影响图像拼接精度的主要因素。     

基于边缘扩展相位相关的图像拼接算法

针对图像拼接算法中计算量大的问题,提出了一种基于边缘扩展相位相关的图像拼接算法。该算法采用迭代阈值分割法对图像进行边缘检测,并对检测出的边缘进行扩展相位相关计算,得出图像间的平移、旋转和尺度变化。利用这些参数拼接图像,用渐进渐出的方法实现拼接图像的融合。实验证明,该算法能够简化计算,并有效地实现图像的拼接。     

基于SIFT-ACO的图像拼接算法

针对具有一定旋转角度的多幅图像拼接问题,提出了一种基于SIFT-ACO的图像拼接算法。对拼接图像进行预处理后,用SIFT算法提取图像特征,将经典的生物智能优化算法ACO加入到图像配准中,对图像特征点进行配准,最后将多幅图像融合,得到一幅宽视角、无缝、高精度的图像。对多组不同角度拍摄的图像进行拼接试验。试验结果表明：在不影响整体视觉效果的前提下,该算法能有效地提高图像拼接精度。     

Temperature field reconstruction of 3D luminous flames based on light field tomography theory

Standard plenoptic camera can be used to capture multi-dimensional radiation information of high temperature luminous flame to reconstruct the temperature distribution. In this study, a novel method for reconstructing three-dimensional temperature field is proposed. This method is based on the optical tomography combined with standard plenoptic camera. The flame projection information from different planes is contained in one radiation image. In this model, we introduced the effective concept of the nearest neighbor method in the frequency domain to strip the interference of redundant information in the projection and to realize three-dimensional deconvolution. The flame emission intensity received by the pixels on the charge-coupled device sensor can be obtained according to the optical tomographic model. The temperature distributions of the axisymmetric and nonaxisymmetric flames can be reconstructed by solving the mathematical model with the nearest neighbor method. The numerical results show that three-dimensional temperature fields of high temperature luminous flames can be retrieved, proving the validity of the proposed method.     

基于三维模型的多姿态人脸识别

利用正面、侧面照片建立起三维虚拟人脸模型，对待识别照片进行角度估计，把人脸三维模型进行投影，将多姿态识别转换成同一角度下两张照片的识别，从而解决了人脸的多姿态识别问题．提出了一种完整的解决人脸多姿态识别的方案，并提出了一种新的计算待识别照片旋转角度的算法．     

基于宽基线立体视觉的远距离三维重建

针对月球车视觉导航中远距离场景的三维重建问题,提出一种基于相机自标定的宽基线立体视觉方法.该方法首先提取立体图对的尺寸不变性(SIFT)特征并进行匹配,得到特征点对应关系;再使用外极线几何约束描述立体图像校正的直射变换,对其Sampson误差使用Levenberg-Marquardt(LM)算法求得最小二乘最优解,完成相机参数估计和图像校正;对校正后的图像使用种子像素视差扩张算法进行宽基线立体匹配,根据匹配得到的视差完成目标场景三维重建.实验表明:该方法解决了月球车相机的现场标定难题,并能够解决宽基线立体视觉面临的光照差异、透视畸变、遮挡等问题,对远距离山脉等自然场景的三维重建效果良好,重建精度较高.     

Concept of the Solar Ring mission: Preliminary design and mission profile

The Solar Ring mission, a concept to monitor the Sun and inner heliosphere from multiple perspectives, has been funded for prephase study by the Strategic Priority Program of Chinese Academy of Sciences in space sciences. The Solar Ring is comprised of 6 spacecraft, grouped in three pairs, moving around the Sun in an elliptical orbit in the ecliptic plane. The mission costs,including launch fee, deep-space maneuvers, and deployment time of the ring, are highly relevant to the working orbit, deepspace transfer, and phase angle within a group. The preliminary mission profile is analyzed and designed in this paper. The launch way, two spacecraft with one rocket, is adopted. The deployment time, phasing maneuvers, and C_3 of launch energy are evaluated for the elliptical orbits with the perihelion between 0.7 and 0.9 AU using the rockets of Long March(LM) 3A and 3B.Numerical simulations show two candidate trajectories: fast deployment within 4 years by LM-3B, medium deployment more than 6 years by cheaper rocket of LM-3A. In order to obtain both fast deployment and low launch cost, another orbit profile is proposed by shortening the phase angle within a group. The suggested working orbits and the corresponding costs of launch,deployment time, and phasing maneuvers will strongly support the science objectives.     

Three-dimensional temperature reconstruction of diffusion flame from the light-field convolution imaging by the focused plenoptic camera

The plenoptic imaging technique provides a promising approach to the non-invasive three-dimensional measurement, especially for the high-temperature combustion diagnosis. We establish a light-field convolution imaging model for diffusion flame in this work, considering the radiation transfer process inside the diffusion flame and the light transfer process inside the focused plenoptic camera together. The radiation transfer process is described by the radiation transfer equation and solved by the generalized source multi-flux method. Wave optics theory is adopted to describe the light transfer process, combining Fresnel diffraction and the phase conversion of the lens. The flame light-field image is obtained by the light-field convolution imaging model and adopted as the measurement signal to reconstruct three-dimensional temperature field. The inverse problem of temperature reconstruction is solved by the least square QR decomposition method. The simulative temperature reconstruction work is conducted, including the inverse analysis, the uncertainty analysis, and the measurement noise influence. All the results show that the proposed measurement method is available to reconstruct three-dimensional temperature with satisfactory accuracy and acceptable uncertainty. Both symmetric and asymmetric distributed temperature fields are investigated, and the reconstructed results prove the validity and universality of the measurement method.

     

三维稀疏散乱点集的直接三角剖分新方法

给出一种三维稀疏散乱点集在三维空间直接进行三角剖分的新方法——在形成初始三角形后对它周围的离散点循环三角化．通过在剖分过程中引入两相邻三角形的最小夹角、最优点搜索半径系数和最小张角这三个剖分参数,实现了任意三维稀疏散乱点集的完全剖分以及非封闭自由曲面边界的自动识别．针对某些特殊复杂曲面上稀疏散乱点集的剖分问题提出了“分部剖分”思想：根据曲面的特征在不同区域设置不同的剖分参数．实例表明,这种直接剖分方法能有效处理任意多连通封闭和非封闭自由曲面上的稀疏散乱点集的三角剖分问题．     

Predicting the dynamic behavior of asphalt concrete using three-dimensional discrete element method

A user-defined three-dimensional(3D)discrete element model was presented to predict the dynamic modulus and phase angle of asphalt concrete(AC).The 3D discrete element method(DEM)model of AC was constructed employing a user-defined computer program developed using the "Fish" language in PFC3D.Important microstructural features of AC were modeled,including aggregate gradation,air voids and mastic.The irregular shape of aggregate particle was modeled using a clump of spheres.The developed model was validated through comparing with experimental measurements and then used to simulate the cyclic uniaxial compression test,based on which the dynamic modulus and phase angle were calculated from the output stress-strain relationship.The effects of air void content,aggregate stiffness and volumetric fraction on AC modulus were further investigated.The experimental results show that the 3D DEM model is able to accurately predict both dynamic modulus and phase angle of AC across a range of temperature and loading frequencies.The user-defined 3D model also demonstrated significant improvement over the general existing two-dimensional models.     

Shock control bump optimization for a low sweep supercritical wing

Shock control bumps are a promising technique in reducing wave drag of civil transport aircraft flying at transonic speeds.This paper investigates the optimization of 3D shock control bumps on a supercritical wing with a sweep angle of 16°at the1/4 chord.A similar supercritical wing with a higher sweep angle of 24.5°at the 1/4 chord has been adopted as a baseline for the study.Numerical results show that the drag coefficient of the low sweep wing with the optimized 3D shock control bumps is reduced below that for the high sweep wing,indicating shock control bumps can be used as an effective means to reduce the wave drag caused by reducing the wing sweep angle.From the point of view of the wing structure design,lower sweep angle will also bring the benefits of weight reduction,resulting in further fuel reduction.     

基于角向功率谱的复合材料预制件表面编织角的测量

基于纹理分析理论，采用谱分析技术，对三维编织复合材料预制件表面边缘图像进行傅立叶变换，得到其功率谱图和角向功率谱图，可进行平均编织角测量．与传统的三点法、四点法和手工测量法比较，结果表明，该方法的测量结果与手工法设计参数相吻合，对三维编织复合材料预制件表面编织角的自动测量具有实际意义和理论价值．     

Influences of nonassociated flow rules on three-dimensional seismic stability of loaded slopes

The influences of soil dilatancy angle on three-dimensional (3D) seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilatancy angle of soil and the coefficient of seismic load.