基于OSG的油藏三维可视化系统研究

为了直观、逼真地展现地下油藏构造的真实形态及储层物性参数的分布规律等,设计并实现了一种基于开源软件OSG的油藏三维可视化系统。该系统充分利用OSG的特点和功能,完成了三维油藏模型漫游、缩放和任意剖切等交互操作功能。同时重点研究实现了绘制油藏彩色模型、提高网格模型视觉效果等技术。将该系统应用于中石化胜利油田实际油藏区块,取得了较好的效果。     

异种油藏网格模型三维可视化优化方法研究

在油藏三维建模和数值模拟软件中,网格模型在存储格式、网格排序等方面存在较大差异,且大规模网格模型将占用大量存储空间同时需要运算大量数据,限制其绘制速度。为此,提出了异种油藏网格模型三维可视化优化方法,加载异种油藏网格模型,并实现网格模型消隐算法,提高油藏网格模型的绘制速度。实验结果表明,该方法能够加载异种油藏网格模型,与优化前的网格模型相比,优化后的模型在存储、绘制速度和效果上有着明显的优势。     

基于表面模型的油藏储层可视化算法研究

油藏储层的可视化可以直观和充分地反映油藏储层参数在空间的分布状态，文章研究了基于表面模型的油藏储层可视化的相关算法，它包含三维网格化数据体的建立、可视化数据的形成以及模型的映射和着色。在网格化和可视面数据形成的过程中，采用随机模拟的方法，针对不同的属性参数分别建模，符合地质认识，最后给出了油藏储层分布的实例，达到了将油藏储层直观展示的目的。     

油藏储集体模式可视化的研究与实现

油藏储集体可视化是油藏描述过程中非常重要的一个环节，它可以帮助油藏开采、勘查工程师迅速准确地了解和掌握油藏分布，从而做出准确的决策，本文研究并解决了油藏储集体可视化过程中的关键问题，首先，通过建立三角网格表示的油藏储集体顶底面构造和尖灭线模型来确定油藏储集体的几何位置和形态，其次，用克里金插值的方法建立油藏储集体的各种物性参数数据场，最后，给出了某油藏储集体物性分布的实例，其结果达到了将油藏描述的结果用三维图象直观展现出来的目的。     

数字油田地上下三维集成建模系统研究

在对油田地上下二三维建模过程中各类数据分类和解析的基础上,采用地上CSG+地表GRID+地下Pillar混合模型建立地上下统一的数据结构和接口,分析三维地形、三维油藏、三维地物、地表二维矢量三维化、坐标系与坐标转换等可视化建模方法,根据OSG平台建立统一的三维场景,提出基于面的三维网格消隐算法和基于离散属性值的邻域作用力网格平滑算法,研究三维垂向剖切、剖切面展布与井轨迹在剖面上的投影,实现基于遗传算法的水平井水平段设计优化技术。以内蒙古某油田为实验对象,结果表明,该系统可用于数字油田地上下三维集成建模。     

一种适于黑油模型并行的快速新解法--改进的GMRES算法

本文应用区域分解算法进行油藏模拟的并行计算研究,寻求可高效并行求解三维三相数值模拟问题的最优算法。在对流行的预处理共轭梯度算法及GMRES算法进行对比研究的基础上,提出了改进的GMRES算法,这种算法具有迭代参数不需优化、收敛快、可得到较精确解等优点。应用该解法对三维三相黑油模型软件进行并行化改造。通过模型及实际油藏计算,比软件原算法及GMRES算法的计算速度得到大幅度提高。并行效率较高,并行化后的模拟软件可以有效地解决大型整装构造油藏的数值模拟问题。     

油气储层垂向折面剖切及二三维可视化研究

针对三维油气藏模型剖切及剖面图可视化,给出了解决方案包括以下部分:设计了适用于多种油藏模型文件的统一数据模型及接口;三维油气藏模型剖切,剖切的思想是将六面体每个面及剖切线所在的面划分为三角形,利用三角形两两相交的算法求取交线段,并形成油藏剖面;简要描述了井轨迹的压缩算法及井轨迹投影到油藏剖面的方法;最后讨论了三维剖面的二维展布方法。算法通过编程实现,并利用实际油气藏模型进行测试,测试结果表明,算法及流程可行性强,并具有灵活、高效等优点。     

三维热传导方程的Krylov子空间方法并行分析

热传导方程在地下水流动数值模拟、油藏数值模拟等工程计算中有着广泛应用,其并行实现是加速问题求解速度、提高问题求解规模的重要手段,因此热传导方程的并行求解具有重要意义。对Krylov子空间方法中的CG和GMRES算法进行并行分析,并对不同的预处理CG算法作了比较。在Linux集群系统上,以三维热传导模型为例进行了数值实验。实验结果表明,CG算法比GMRES算法更适合建立三维热传导模型的并行求解。此外,CG算法与BJACOBI预条件子的整合在求解该热传导模型时,其并行程序具有良好的加速比和效率。因此,采用BJACOBI预处理技术的CG算法是一种较好的求解三维热传导模型的并行方案。     

低渗透油藏地质工程一体化三维平台的设计与实现

针对低渗透油藏开发中遇到的不同专业的三维建模、数值模拟软件分析成果格式不统一,难以综合分析利用的问题,应用三维可视化技术设计并开发了一种可以兼容多种格式的三维平台,实现了对地质模型、地应力分布模型、人工裂缝模拟结果的综合展示,并在此基础上提供了非规则井网布井功能,为低渗透油藏地质工程一体化开发提供了一种有效的分析工具。     

低渗透油藏地质工程一体化三维平台的设计与实现

针对低渗透油藏开发中遇到的不同专业的三维建模、数值模拟软件分析成果格式不统一,难以综合分析利用的问题,应用三维可视化技术设计并开发了一种可以兼容多种格式的三维平台,实现了对地质模型、地应力分布模型、人工裂缝模拟结果的综合展示,并在此基础上提供了非规则井网布井功能,为低渗透油藏地质工程一体化开发提供了一种有效的分析工具。     

基于改进ASM的三维人脸自动对齐算法

针对传统三维人脸对齐算法需要大量人工操作和数据冗余的不足,提出一种基于改进主动形状模型的三维人脸自动对齐算法。该算法对二维人脸进行快速自动特征定位,根据三维人脸柱面展开的二维纹理图进行自动特征定位并分片。采用基于平面模板的重采样算法,自动实现三维人脸顶点稠密对齐。实验结果表明,该算法在提高运算速率的同时,得到的归一化结果与原始数据仍能保持99%形状相似度。     

Examplar coherent 3D face reconstruction from forensic mugshot database

Reconstructing 3D face models from 2D face images is usually done by using a single reference 3D face model or some gender/ethnicity specific 3D face models. However, different persons, even those of the same gender or ethnicity, usually have significantly different faces in terms of their overall appearance, which forms the base of person recognition via faces. Consequently, existing 3D reference model based methods have limited capability of reconstructing precise 3D face models for a large variety of persons. In this paper, we propose to explore a reservoir of diverse reference models for 3D face reconstruction from forensic mugshot face images, where facial examplars coherent with the input determine the final shape estimation. Specifically, our 3D face reconstruction is formulated as an energy minimization problem with: 1) shading constraint from multiple input face images, 2) distortion and self-occlusion based color consistency between different views, and 3) depth uncertainty based smoothness constraint on adjacent pixels. The proposed energy is minimized in a coarse to fine way, where the shape refinement step is done by using a multi-label segmentation algorithm. Experimental results on challenging datasets demonstrate that the proposed algorithm is capable of recovering high quality 3D face models. We also show that our reconstructed models successfully boost face recognition accuracy.     

重建发型的真实感头部建模

提出了从几何模型和多视点彩色图像构造真实感三维头部模型的方法．作为输入数据的彩色图像不仅被用来构造全景纹理图,而且是发型重构的数据源．首先在模型空间定义对应于真实图像平面的虚拟图像平面,恢复不同视点图像中发型外轮廓点的相应三维位置;然后根据发根位置、生长方向和长度,在模型的头皮表面重建发型．另一种发型重构的方法是从多幅图像中抽取的二维发型轮廓线出发,通过立体匹配法恢复其三维位置．然后用Coons-patch法重构发型表面．实验结果显示了文中方法的头部重建效果．     

Color adjustment in image-based texture maps

We propose a color adjustment technique to eliminate the visible seams in image-based texture map of a 3D object. The process is carried out in three steps. First, texture coordinates are locally displaced to minimize the misalignment of adjacent texture patches. Second, color discontinuities between different texture patches at each corner of the mesh faces are resolved. We minimize a global energy function over the mesh to ensure continuous color transitions and fit the color gradient at each corner of the mesh faces. Finally, the color adjustment at the corners is propagated over the texture patch for each face by solving a Poisson equation with mixed boundary conditions. By means of the proposed processing techniques, the visibility of seams is minimized while fine details are preserved in image-based texture maps. This can be used as a last refinement stage in image-based 3D reconstruction pipelines. The proposed color adjustment algorithm is tested on a variety of real-world datasets and compares very favorably with known methods.     

实时更新的全局一致三维栅格建图

在未知的三维环境中,移动机器人自主导航通常需要实时构建与环境全局一致的栅格地图,而现有大部分系统缺少地图更新策略,构建的栅格地图与实际环境不一致.文中将同步定位与建图模块获得的环境信息以点云形式提供给栅格建图模块处理,同时提出基于关键帧的高效数据结构和地图实时更新策略,实时构建可用于移动机器人自主导航的全局一致的地图.室内动态的实验数据测试表明,文中方法可以有效实时更新地图,生成与环境一致的三维栅格地图,支持其后续的自主导航操作.     

Texture Mapping Real‐World Objects with Hydrographics

In the digital world, assigning arbitrary colors to an object is a simple operation thanks to texture mapping. However, in the real world, the same basic function of applying colors onto an object is far from trivial. One can specify colors during the fabrication process using a color 3D printer, but this does not apply to already existing objects. Paint and decals can be used during post‐fabrication, but they are challenging to apply on complex shapes. In this paper, we develop a method to enable texture mapping of physical objects, that is, we allow one to map an arbitrary color image onto a three‐dimensional object. Our approach builds upon hydrographics, a technique to transfer pigments printed on a sheet of polymer onto curved surfaces. We first describe a setup that makes the traditional water transfer printing process more accurate and consistent across prints. We then simulate the transfer process using a specialized parameterization to estimate the mapping between the planar color map and the object surface. We demonstrate that our approach enables the application of detailed color maps onto complex shapes such as 3D models of faces and anatomical casts.     

一种新的地物与地形的网格融合方法

三维地形可视化中重要的地物模型需要使用CAD软件（3D Studio MAX/AutoCAD（3D）/MultiGen）构建的模型数据,来逼真表示城市的精细结构、材质特征及地物的内部形态,在将其和地形网格集成的过程中,必须让地物和地形之间实现无缝融合。提出了一种新的地物和地形的融合方法：首先读取地形高度图,利用基于四叉树的LOD技术生成地形网格,其次导入三维地物模型并放置于地形网格某位置,对三维地物模型投影得到地物模型的底面网格边界框及点集,地物边界框对应的地形网格分裂,产生融合位置的地形网格边界及对应点集,根据地物网格边界和地形网格边界的这两个点集以及Delauney三角形限定条件生成三角网,实现网格融合。利用该方法实现了四叉树LOD技术生成的地形和地物的融合,最后讨论了该方法的特点及应用。     

Comparative Evaluation of the Consistency of Three‐dimensional Spatial Representations used in Autonomous Robot Navigation

An increasing number of robots for outdoor applications rely on complex three‐dimensional (3D) environmental models. In many cases, 3D maps are used for vital tasks, such as path planning and collision detection in challenging semistructured environments. Thus, acquiring accurate three‐dimensional maps is an important research topic of high priority for autonomously navigating robots. This article proposes an evaluation method that is designed to compare the consistency with which different representations model the environment. In particular, the article examines several popular (probabilistic) spatial representations that are capable of predicting the occupancy of any point in space, given prior 3D range measurements. This work proposes to reformulate the obtained environmental models as probabilistic binary classifiers, thus allowing for the use of standard evaluation and comparison procedures. To avoid introducing localization errors, this article concentrates on evaluating models constructed from measurements acquired at fixed sensor poses. Using a cross‐validation approach, the consistency of different representations, i.e., the likelihood of correctly predicting unseen measurements in the sensor field of view, can be evaluated. Simulated and real‐world data sets are used to benchmark the precision of four spatial models—occupancy grid, triangle mesh, and two variations of the three‐dimensional normal distributions transform (3D‐NDT)—over various environments and sensor noise levels. Overall, the consistency of representation of the 3D‐NDT is found to be the highest among the tested models, with a similar performance over varying input data. © 2013 Wiley Periodicals, Inc.     

创建中国人三维人脸库关键技术研究

通过CyberWare人脸专用扫描仪获取高分辨率的彩色三维人脸来构建中国人三维人脸数据库．创建三维人脸数据库时,要对原始三维人脸数据进行预处理,并通过规格化将三维人脸表示为统一的标准形式．规格化的关键是要建立三维人脸数据基于特征的稠密对应,这是图形学和计算机视觉中的难点问题,目前使用光流方法建立的对应效果并不理想,因此提出了基于网格重采样的计算方法,取得了良好的对应效果．     

The effect of depth map up-sampling on the overall quality of stereopairs

The quality of depth maps affects the quality of generated 3D content. Practically, the depth maps often have lower resolution than that of color images, thus, Depth map Up-sampling (DU) is needed in various 3D applications. DU can yield specific artifacts which can degrade the quality of depth maps as well as constructed stereoscopic (color plus depth map) images. This paper investigates the effect of DU on 3D perception. The depth maps were up-sampled using seven approaches and the quality of stereoscopic images obtained from up-sampled depth maps was estimated through subjective and objective tests. The objective quality prediction was performed using a depth map quality assessment framework. The method is able to predict the quality of stereoscopic images through evaluation of their corresponding up-sampled depth maps using 2D Image Quality Metrics (IQMs). In order to improve the quality estimation, the framework selects the 2D IQMs with highest correlation to subjective test. Furthermore, motivated by previous researches on multiple metrics combination, a new metric fusion method is proposed. Experimental results show that the combined metric delivers higher performance than single metrics in 3D quality prediction.