A 3D Model Reconstruction Method Using Slice Images

Abstract：reconstruction method using slice im-ages is proposed. Wanting to extract the outermost contours from slice images, the method of the improved GVF-Snake model with optimized force field and ray method is employed. And then, the 3D model is reconstructed by contour connection using the im-proved shortest diagonal method and judgment function of contour fracture. The results show that the accuracy of reconstruction 3D model is improved.     

一种三维准欧氏重建方法

研究在不必精确知道相机内参数的情况下进行场景的三维重建，充分利用建筑场景的平面信息，假设场景由一些基本平面元素组成，从而自动生成场景的拓扑结构．虽然重建结果从严格意义上仍是射影重建，但已经非常接近欧氏重建结果，文中称之为准欧氏重建，该结果还可以为其它优化算法提供很好的初值．真实图像的实验结果证实了本文算法，重建模型达到了很好的可视效果．     

New Visual Invariants for Terrain Navigation Without 3D Reconstruction

For autonomous vehicles to achieve terrain navigation, obstacles must be discriminated from terrain before any path planning and obstacle avoidance activity is undertaken. In this paper, a novel approach to obstacle detection has been developed. The method finds obstacles in the 2D image space, as opposed to 3D reconstructed space, using optical flow. Our method assumes that both nonobstacle terrain regions, as well as regions with obstacles, will be visible in the imagery. Therefore, our goal is to discriminate between terrain regions with obstacles and terrain regions without obstacles. Our method uses new visual linear invariants based on optical flow. Employing the linear invariance property, obstacles can be directly detected by using reference flow lines obtained from measured optical flow. The main features of this approach are: (1) 2D visual information (i.e., optical flow) is directly used to detect obstacles; no range, 3D motion, or 3D scene geometry is recovered; (2) knowledge about the camera-to-ground coordinate transformation is not required; (3) knowledge about vehicle (or camera) motion is not required; (4) the method is valid for the vehicle (or camera) undergoing general six-degree-of-freedom motion; (5) the error sources involved are reduced to a minimum, because the only information required is one component of optical flow. Numerous experiments using both synthetic and real image data are presented. Our methods are demonstrated in both ground and air vehicle scenarios.     

运用特殊投影法建立多变量问题的三维模型

运用特殊投影法,建立了四至七维空间直角坐标系在三维空间的投影模型,获得了四到七维几何元素投影到三维空间的变换矩阵,使多变量的几何和复变函数模型得以正确显示。     

基于虚拟高度投影线的三维重建及误差补偿

针对传统三维重建方法计算复杂度高的问题,提出一种基于虚拟高度投影线的三维重建方法。该方法将场景栅格化,在栅格中引入虚拟高度线,把虚拟高度线投影到二维图像上形成投影线,并在投影线上找到对应点得到三维场景信息,以反映场景的真实信息。分析引起误差的主要来源,针对误差来源结合摄像机内外参数提出补偿方法。通过实验验证了该方法的有效性。     

3D Surface Reconstruction Using Occluding Contours

This paper addresses the problem of 3D surface reconstruction using image sequences. It has been shown that shape recovery from three or more occluding contours of the surface is possible given a known camera motion. Several algorithms, which have been recently proposed, allow such a reconstruction under the assumption of a linear camera motion. A new approach is presented which deals with the reconstruction problem directly from a discrete point of view. First, a theoretical study of the epipolar correspondence between occluding contours is achieved. A correct depth formulation is then derived from a local approximation of the surface up to order two. This allows the local shape to be estimated, given three consecutive contours, without any constraints on the camera motion. Experimental results are presented for both synthetic and real data.     

Large-scale 3D Semantic Mapping Using Stereo Vision

In recent years, there have been a lot of interests in incorporating semantics into simultaneous localization and mapping (SLAM) systems. This paper presents an approach to generate an outdoor large-scale 3D dense semantic map based on binocular stereo vision. The inputs to system are stereo color images from a moving vehicle. First, dense 3D space around the vehicle is constructed, and the motion of camera is estimated by visual odometry. Meanwhile, semantic segmentation is performed through the deep learning technology online, and the semantic labels are also used to verify the feature matching in visual odometry. These three processes calculate the motion, depth and semantic label of every pixel in the input views. Then, a voxel conditional random field (CRF) inference is introduced to fuse semantic labels to voxel. After that, we present a method to remove the moving objects by incorporating the semantic labels, which improves the motion segmentation accuracy. The last is to generate the dense 3D semantic map of an urban environment from arbitrary long image sequence. We evaluate our approach on KITTI vision benchmark, and the results show that the proposed method is effective.     

基于纹路的三维指纹模型重建算法

三维指纹识别是近几年兴起的一种基于三维指纹模型进行指纹识别的新技术,能够克服传统接触式指纹识别中存在的纹路变形、残留纹路、对手指皮肤状况敏感等缺陷。基于多角度图像的三维指纹模型重建是整个识别过程中的一个关键步骤。提出了一种基于纹路的重建算法,算法重建的指纹模型直接包含纹路与细节点相关特征。相对于已有文献中将指纹表皮作为重建对象,算法重建结果更有助于特征提取等三维指纹识别后续过程。     

一种改进的三维人脸重构方法

提出一种改进的三维人脸重构方法。该方法采用基于单个相机的双目立体视觉系统对人脸进行采样,根据人脸对称性假设,运用补洞与纠错技术进行自动点云优化。继而采用简化的Candide-3模型作为细分初始控制网格,局部加细地进行细分曲面分层次拟合操作,采用测地线映射技术对不同表情进行归一化,并分别建立人脸数据库。实验结果表明,采用单相机立体视觉系统在提高重建精度的同时,很大程度上避免由于双相机拍摄不同步引起的重建鲁棒性降低问题。而采用细分曲面作为存储结构,在节约空间的前提下,为分层次比对筛选提供理论支持。该系统成本较低,适合在许多领域推广应用。     

建筑物三维场景重建方法

针对建筑物模型的规则性问题,基于一幅或多幅非标定图像,对建筑物结构进行多视角三维场景重建,得到360°观测模型。区别于传统三维重建方法,该方法无需先标定摄像机参数与逐点配准、不依赖深度数据和高分辨率图像。实验结果表明该方法解决了单张图像方向性感知视野受限的问题,在系统复杂度和速度上优于传统方法。     

单图三维重构方法

在场景深度信息未知的情况下,由多视点成像产生的焦散失真是无法消除的。针对该问题,利用多视点成像中光束斜交的特性,提取失真图像中结构化图形中包含的场景深度信息,实现对单幅多视点图像的三维几何结构重建。重构适用范围包括所有已知函数形式的曲线,尤其为直线、圆等特殊几何图形的三维重构提供了专门的数学方法。     

三维表面重构过程参数的估计研究

在SFS(基于阴影的三维表面重构)各种算法中,都需要光源方向及曲面反射率。这些参数与图像的恢复效果息息相关。针对这些参数,也应运而生了各种各样的行之有效的方法。论文讨论了两种有效的算法,利用合成图像分别进行试验,并对其优缺点和运行效率进行比较,从而为进一步的SFS算法研究提供有价值的参考。     

3D Keypoint Estimation Using Implicit Representation Learning

In this paper, we tackle the challenging problem of 3D keypoint estimation of general objects using a novel implicit representation. Previous works have demonstrated promising results for keypoint prediction through direct coordinate regression or heatmap-based inference. However, these methods are commonly studied for specific subjects, such as human bodies and faces, which possess fixed keypoint structures. They also suffer in several practical scenarios where explicit or complete geometry is not given, including images and partial point clouds. Inspired by the recent success of advanced implicit representation in reconstruction tasks, we explore the idea of using an implicit field to represent keypoints. Specifically, our key idea is employing spheres to represent 3D keypoints, thereby enabling the learnability of the corresponding signed distance field. Explicit key-points can be extracted subsequently by our algorithm based on the Hough transform. Quantitative and qualitative evaluations also show the superiority of our representation in terms of prediction accuracy.     

多尺度特征融合重建的行人检测方法

行人在众多场景中都存在多尺度变化问题,严重影响检测器的精度,为此设计卷积特征重建和通道注意力两种模块来增强对多尺度行人的检测效果.以原始输入的多尺度特征为基础融合重建多个特征金字塔,然后融合多个特征金字塔中的相同尺度特征,并学习每层特征的通道注意力权值来增加有效通道层权重,由此得到的特征才用于最后的检测.将这两种模块集...     

基于标定物的相机标定及三维重建

针对传统三维建模的局限性,讨论了一种基于图像建模的技术,提出了利用普通相机和标定物对物体进行三维建模的方法,该方法利用一个在左右图像都存在的物体,对相机进行标定[1]。然后利用左右相机的相机矩阵,反算空间中的对应点和需要求取的关键点。最后利用这些点计算出来的空间位置[2],对物体进行重建,并用OpenGL进行漫游显示。实验表明,该算法计算准确,鲁棒性很高,能够满足于虚拟现实的需要。     

一种变形表面的三维测量方法

提出一种新的利用标定图像进行三维测量的方法。利用SIFT算法找到初始的对应点,然后根据这些点生成三维空间中的种子点,再以这些种子点为中心,向外区域增长,直到完成整个物体表面测量。在每次增长的过程中,需要计算增长的三维空间平面在两个相机上的投影之间的图像相关系数。图像相关系数较大时认为是正确的增长,否则是错误的增长。实验证明,使用该方法能够得到很好的三维测量结果。     

一种半自动的三维欧氏重建方法

从二维图像得到场景的三维模型是计算机视觉和虚拟现实的重要研究内容。本文通过用户的简单交互,利用平面型场景的同形关系自动进行两幅大差异图像之间的角点匹配,将这些匹配结果作为初始点,再利用RANSAC鲁棒算法估计基本矩阵。以此结果进行仿射重建,然后在简化相机模型的基础上通过给出的约束条件直接实现欧氏重建,真实数据的实验结果表明了该算法的有效性。     

三维建筑模型的规则化重构方法

基于无人机照片的倾斜摄影测量技术能够快速重建大量三维建筑模型;但这些模型数据量大、噪声多,极大阻碍了在智慧城市中的应用.针对倾斜摄影测量重建的三维建筑模型屋顶重建精度较高的特点,提出一种基于屋顶轮廓线的三维建筑模型规则化重构方法.首先分割屋顶并提取屋顶的外轮廓线;接着通过改进的平面拟合提取屋顶的内轮廓线;然后由屋顶内外...     

考古地层的三维重建方法*

基于现有三维可视化技术,分别介绍了3D图形库接口、3D GIS技术、3D GMS技术、虚拟现实技术等可以实现考古地层三维重建的方法,并从地层三维建模的角度比较了各种方法的特点,探讨了较为实用的考古地层三维重建途径.     

肿瘤细胞断层图像轮廓的三维极坐标插值方法

利用“细胞CT”——激光扫描共聚焦显微镜可以获得肿瘤细胞三维断层图像,实现肿瘤细胞三维可视化,为此提出了一种针对细胞断层图像轮廓的三维极坐标插值方法,以图形形态学中心为极坐标原点,将轮廓点转换为由极坐标表示.按极角采样获得离散轮廓点数据,综合多层轮廓信息,依照表面轮廓变化趋势,进行均匀三次B样条拟合完成插值.针对肿瘤细胞核常见的分支核结构,利用曲率角点检测和数学形态学相结合的方法实现轮廓分割,并采用基于阈值半径的轮廓匹配方法实现分支轮廓对应,继而实现细胞分支核插值.结果显示,本方法可实现细胞及细胞核的三维插值,插值后轮廓表面三维重建表现出良好的曲面光滑性和连续性,表明极坐标插值数据可为细胞三维形态结构测量提供便利.