二维-三维特征融合的古铜镜纹饰提取方法

纹饰提取对残损文物数字化修复具有重要意义。针对出土的西汉铜镜纹饰表面铜绿覆盖、边缘侵蚀模糊、轮廓特征难以提取等问题,提出了一种融合二维和三维特征的古铜镜纹饰提取方法。借助微距镜头相机和超景深显微镜采集古铜镜碎片的二维和三维影像,根据2种维度信息的不同特点进行图像预处理和二维、三维特征模型的构建。将稀疏表示技术与古铜镜表面纹饰的二维和三维特征相融合,提取完整的古铜镜纹饰轮廓,并通过形态学处理和轮廓平滑技术强化纹饰图像。结果表明,“高清相机+超景深显微镜”的原始纹饰图案采集模式结合基于稀疏表示的特征融合技术能够解决薄小碎片纹饰图案难以准确提取的问题,可以原真性还原古铜镜纹饰。

饱和软土二维-三维列车振动响应对比分析

针对岩土工程中常用二维模型等效三维模型进行数值计算的方法,对列车运行引起的二维和三维动力响应进行了分析.根据钢轨-扣件-隧道-地基纵向模型得到作用于隧道道床上的振动荷载,基于循环流动本构模型和土-水完全耦合理论,计算了列车平均时速下饱和软土层二维和三维的振动响应规律.研究结果表明:两种模型的地表振动加速度、位移以及隧道周围超孔隙水压力在横截面内规律基本相似但数值相差较大;二维-三维地表加速度比和位移比最大值分别可达9倍和6倍,加速度振级相差可达15 d B;隧道周围的二维-三维超孔压比在1.5~3.5之间,单次振动超孔压累积值可达4.36 k Pa和1.69 k Pa,且在隧道竖轴左右45°及135°位置处超孔压力累积最为明显;振动荷载形式、纵向土层振动、固结速度是造成饱和土软土二维-三维列车振动响应差异的主要原因.

可扩充预定义模型种类和组合方式的二维-三维重建

以模型匹配为基础的三维重建算法的重建效率较高,但重建范围受到预定义模型种类和组合方式的限制。提出了一个可扩充预定义模型种类和组合方式的二维-三维重建算法和相应的软件,并详述该重建算法和相应的软件如何解决由垂直拉伸模型、绕垂直视图平面轴整周旋扫模型和简单棱锥体模型通过并和差所构成组合模型的三维重建,以后只要在可扩充预定义模型部分加入其它模型种类和组合方式就可以扩大三维重建的范围。

基于二维超声-三维CT配准的肾脏穿刺定位方法可行性研究

医学影像引导的经皮肾穿刺手术是经皮肾镜取石术中建立手术通道的重要手段,高质量的实时医学图像可以提高术中穿刺精度,减少手术风险。针对自由呼吸下经皮肾穿刺靶点的导航定位问题,该研究提出了一种基于术中二维超声-术前三维CT实时配准的肾脏穿刺定位方法。首先对肾脏轮廓特征的二维超声图像和三维CT图像进行由粗到精的快速配准,然后通过超声探头标定,将配准融合后的图像注册到手术空间,实现穿刺靶点的实时定位。人体腹部模型实验结果表明,超声探头标定均方根误差为0.998 mm,二维超声和三维CT数据配准误差为0.709 mm,平均配准运算时间为1.15 s,最终的平均定位误差为2.265 mm。

颈椎轴向旋转时各节段间在体三维运动特点

目的测定生理载荷下颈椎轴向旋转时各运动节段的三维运动数据并分析颈椎的耦合运动特点。方法招募16名健康志愿者,排除颈椎病史、颈部疼痛不适及发育畸形,年龄22~29岁(中位年龄23岁)。采用双X线透视成像系统和CT相结合的技术,将颈椎的CT扫描图像导入计算机三维建模软件,建立颈椎三维模型;然后将模型与双X线透视成像系统捕获的最大左旋、右旋位的颈椎双平面透视的二维影像相匹配,在计算机软件的坐标系中再现颈椎的三维运动,进而算出颈椎最大轴向旋转时各节段的三维运动数据。结果 (1)颈椎轴向旋转时,C1/2旋转范围占颈椎整体旋转角度的绝大部分;下颈椎各节段中以C3/4、C5/6节段轴向旋转范围最大,C2/3最小。(2)颈椎轴向旋转时,C1/2耦合侧屈方向与轴向旋转方向相反;C2/3、C3/4、C4/5、C5/6、C6/7节段的耦合侧屈方向与轴向旋转方向相同,其中C2/3的耦合侧屈角度明显小于C3/4、C4/5、C5/6节段。结论应用二维-三维匹配技术测量颈椎轴向旋转时各节段的三维运动数据,得出颈椎轴向旋转时的耦合运动特点,有助于提高人们对颈椎复杂运动的认知水平,并为颈椎疾病的诊断、治疗及假体设计提供数据支持。

Drishti Paint 3.2:a new open-source tool for both 2D and 3D segmentation

X-ray computed tomography(CT)has been an important technology in paleontology for several decades.It helps researchers to acquire detailed anatomical structures of fossils non-destructively.Despite its widespread application,developing an efficient and user-friendly method for segmenting CT data continues to be a formidable challenge in the field.Most CT data segmentation software operates on 2D interfaces,which limits flexibility for real-time adjustments in 3D segmentation.Here,we introduce Curves Mode in Drishti Paint 3.2,an open-source tool for CT data segmentation.Drishti Paint 3.2 allows users to manually or semi-automatically segment the CT data in both 2D and 3D environments,providing a novel solution for revisualizing CT data in paleontological studies.

Contrast between 2D inversion and 3D inversion based on 2D high-density resistivity data

The 2D data processing adopted by the high-density resistivity method regards the geological structures as two degrees, which makes the results of the 2D data inversion only an approximate interpretation;the accuracy and effect can not meet the precise requirement of the inversion. Two typical models of the geological bodies were designed, and forward calculation was carried out using finite element method. The forward-modeled profiles were obtained. 1% Gaussian random error was added in the forward models and then 2D and 3D inversions using a high-density resistivity method were undertaken to realistically simulate field data and analyze the sensitivity of the 2D and 3D inversion algorithms to noise. Contrast between the 2D and 3D inversion results of least squares inversion shows that two inversion results of high-density resistivity method all can basically reflect the spatial position of an anomalous body. However, the 3D inversion can more effectively eliminate the influence of interference from Gaussian random error and better reflect the distribution of resistivity in the anomalous bodies. Overall, the 3D inversion was better than 2D inversion in terms of embodying anomalous body positions, morphology and resistivity properties.

Two-and Three-Dimensional Urban Core Determinants of the Urban Heat Island： A Statistical Approach

There is no doubt that the UHI （urban heat island） is a mounting problem in built-up environments, due to the energy retention by surface dense building materials, leading to increased temperatures, air pollution, and energy consumption. Much of the earlier research on the UHI has used two-dimensional （2-D） information, such as land uses and the distribution of vegetation. In the case of homogeneous land uses, it is possible to predict surface temperatures with reasonable accuracy with 2-D information. However, three-dimensional （3-D） information is necessary to analyze more complex sites, including dense building clusters. In this research, 3-D building geometry information is combined with 2-D urban surface information to examine the relationship between urban characteristics and temperature. The research includes the following stages： （1） estimating urban temperature; （2） developing a 3-D city model; （3） generating geometric parameters; and （4） conducting statistical analyses using both linear and non-linear regression models. The implications of the results are discussed, providing guidelines for policies aiming to reduce the UHI.

改进互信息与图像金字塔相结合的二维与三维图像配准方法研究

目的探讨改进互信息与图像金字塔相结合的二维-三维配准方法的价值。方法将3次B样条曲线的连续图像表示与Parzen直方图估计融合到该算法中,以胸腔作为研究对象,通过数字重建放射影像生成的正交位的模拟X线图和与其本身进行一定变换后的图像进行配准实验,观察配准精度和时间。结果经过50组对照试验得出本方法相较于传统配准方法在x、y轴向上的位移精度分别提高了53.39%、21.33%,配准时间缩短了91.93%。相较于近几年的改进算法在x、y轴向上的位移精度分别提高了17.65%、13.79%,并将配准时间进一步提高了19.64%。结论该方法可以有效提高二维-三维图像的配准精度和效率,且均符合手术过程中图像配准2 mm以内的要求。该方法的高效、准确为临床诊断和放疗自动化提供了有利的信息,同时也为肿瘤位置误差校正和医用机械臂自动摆位奠定了基础。

Double contrast-enhanced two-dimensional and three-dimensional ultrasonography for evaluation of gastric lesions

AIM： To investigate the value of two-dimensional （2D） and three-dimensional （3D） double contrast-enhanced ultrasonography （DCUS） imaging for evaluation of gas- tric lesions. METHODS： 2D and 3D DCUS imaging with both oral and intravenous administrations of contrast agents was used to assess gastroscopiclly-confirmed gastric lesions in 46 patients with benign and malignant diseases. Initially, liquid-based ultrasound contrast agent （Xinzhang） was given orally at dose of 500-600 mL for conventional ultrasound examination of the gastric lesions, and then a microbubble-based contrast agent （SonoVue） was injected intravenously at dose of 1.2-2.4 mL in bolus fashion to assess the perfusion pattern of the lesions using contrast imaging modes. The parameters derived from time-intensity curves including the arrival time （AT）, time to peak （lq-P）, peak intensity （PI） and en- hanced intensity （EI） were measured on the 2D DCUS imaging. 3D DCUS of the lesions was acquired to dem- onstrate the value of this imaging mode. RESULTS： There were 22 cases with benign lesions including chronic gastritis （n= 5）, gastric ulcer （n = 9）, gastric polyps （n = 3）, gastric stromal tumors （n = 5）, and 24 cases with malignant lesions including gastric cancer （n = 20）, gastric cardia carcinoma （n = 3） and post-operative recurrent gastric cancer （n = 1） in the study, The oral contrast-enhanced ultrasonography （CEUS） imaging of the stomach clearly demonstrated the anatomy of the stomach and morphologic features of gastric lesions, With optimal scanning window and imaging display under oral CEUS, intravenous CEUS clearly showed the perfusion of gastric lesions with various characteristic manifestations. Both 2D and 3D DCUS images clearly demonstrated normal gastric wall as a three-layer structure, from the inside out, hypere- choic mucosa, hypoechoic muscularis and hyperechoic serosa, respectively. There were statistical significant differences of AT （8.68±2.06 vs 10.43 ±2.75, P = 0.017）, PI （34.64 ± 6.63 vs 29.58 ± 8.22, P = 0.023） and EI （29.72 ± 6.69 vs 22.66 ± 7.01, P = 0.001） between malignant lesions and normal gastric wall. However, no differences of AT, PI and EI between benign lesions and normal gastric wall tissue were found. 3D DCUS could intuitively display morphological features and vascularities of the lesions with multiplanar and volume views. 3D DCUS imaging provided comprehen- sive information complementary to 2D imaging. The crater or wellhead appearances and feeding vessels as well as distorted nourishing vasculature of gastric carcinoma were better seen with 3D imaging than 2D imaging. CONCLUSION： DCUS imaging can simultaneouslydisplay the anatomic and perfusion features of gastric lesions. 3D DCUS can provide additional information to 2D DCUS for evaluation of gastric lesions.

On the integration of two-dimensional animation and three-dimensional art animation

In recent years, with the level of science and technology progress, largely to promote the development of animation techniques. Animated film is divided into two-dimensional animation and three-dimensional animation, both in the retention feature animated films, based on the performance of each with different strengths, thus forming a different artistic style. Wherein the two-dimensional animation is the most common one is the most basic form of expression in animation technology is relatively mature and complete, but because of the development of animation techniques, two-dimensional animation can not meet the needs of the audience. Thus, the effective combination of two-dimensional animation and three-dimensional animation technology, the advantages of integration between the two is particularly important, so that innovation in the form of screen performance, enhance audio-visual experience. In this paper, two-dimensional animation and three-dimensional animation skills fusion analysis and research, and put forward a number of specific observations, in order to learn.

An Interactive Point-Picking Method by Combining 2D and 3D Views of a Slice Geometry

Interactive picking is a fundamental task for processing and images. Combining two-dimensional （2D） and three-dimensional digital graphics （3D） views is an important trend in processing medical sliced-geometries. With the goal of accurately picking points in sliced-geometries, we present a method to pick points interactively by combining 2D and 3D views of sliced-geometries. Four view windows are constructed to render sliced-geometries using medical imaging interaction toolkit （MITK）： three for 2D slices parallel to the XY, YZ, and XZ planes and one for surface rendering. Points picked in a view window can be rendered and modified in any window. After a point is picked, it is immediately converted into a world coordinate and stored. Points are only rendered and modified based on their world coordinates. This picking method can be used for fitting, observing, and measuring local regions. This method can also be used for interactive segments. Our experiment shows that the picking method is accurate and has a real-time picking effect.

宗教与美学关系语境中的“抽象”思维和形式

人类的宗教现象与审美现象之间不可分割的关系通过“抽象”思维及其艺术形式被展现;“变形”的艺术风格被原始人类用来表现“神”的特殊属性和形象;“几何”风格则反映出人类通过艺术和宗教活动来追求“规律性”和“永恒性”的强烈冲动;“三维—二维”的艺术形式则清晰地展现出古代东方民族普遍存在的关于“一神论”和“另外一个世界”的“超越性”思维和宗教信仰。

两种千伏级立体平面图像引导放射治疗系统临床一致性研究

目的:对比研究千伏(kV)级iScout图像引导放射治疗定位系统和射波刀Xsight脊柱追踪系统基于骨骼二维-三维(2D-3D)图像配准算法的临床一致性。方法:选取医院收治的30例行第四代射波刀Xsight脊柱追踪系统治疗的患者临床数据资料,采用配置i Scout系统成像几何参数,生成数字重组透视图像作为配准参考图像,加载Xsight系统影像板投影图像,应用i Scout系统骨骼定位方法实现2D-3D图像配准,计算患者病灶位置偏移。参照Xsight系统定位配准数据,选取3个平移头脚(S/I)、左右(L/R)和前后(A/P),以及3个转角绕头脚(Roll)、绕左右(Pitch)和绕前后(Yaw)3个方向共6个自由度作为评价参数,记录并对比两个系统的配准结果。结果:获取30例患者数据资料生成的分别由A、B投影图像构成564组投影图像,分析记录Xsight系统和iScout系统配准结果的差值,S/I、L/R和A/P的3个平移结果的差值分别为(0.100.24)mm、(-0.060.32)mm和(0.110.21)mm;Roll、Pitch和Yaw的3个转角结果的差值分别为(-0.010.35)、(0.070.23)和(0.010.24)。散点分布图显示两个系统6个自由度定位配准结果差值集中分布在0.5之间。结论:iScout系统与Xsight系统均基于kV级X射线2D-3D图像配准立体定位引导技术,临床比对结果一致性好。

体部伽玛刀图像引导技术的发展

体部立体定向放射治疗(SBRT)是立体定向放射外科(SRS)技术和临床应用的自然延伸,是一种在精确图像引导下的大剂量低分次的放射治疗方法。体部伽玛刀是中国自主研发的创新放疗设备,把伽玛射束治疗从头部延伸至体部。在近15年的技术发展和临床实践中,体部伽玛刀沿用了传统的体部框架定位模式,由于缺少足够定位精度,限制了其作为SBRT设备在临床上的广泛使用。近年来,图像引导定位技术开始应用于体部伽玛刀,将为体部伽玛刀SBRT规范治疗开启崭新一页。本文介绍了体部伽玛刀图像引导定位的原理、方法、试验和初步应用。

基于注意力残差网络的跨模态医学图像配准

针对2D-3D医学图像配准方法时间长且容易陷入局部极值的问题,提出一种将注意力机制与残差网络融合的跨模态图像配准方法,使用深度残差网络自动提取图像特征,预测配准变换参数,在卷积块中嵌入混合域的注意力机制,提高网络对重要特征的关注度。根据变换参数的特点,设计分组回归的方式提高配准精度。实验结果表明,上述方法预测位移误差均值为0.07mm,角度误差均值为0.04°,优于其方法;配准时间仅需40ms,远低于传统方法。所提配准方法避免了传统方法循环迭代的过程,有效提高配准效率,满足医学图像配准的实时性和精度需求。

From 2D to 3D GIS for CyberCity

In order to understand the 3D landscape with many h igh buildings in a city, the 2D GIS has to be extended to 3D GIS. The further de velopment of CyberCity has to include various applications of 3D scenes from the outdoor scenes to the indoor ones. In thispaper, some key techniques, such as data management method and dynamicalvisualization method for the outdoor and the indoor scenes, are discussed.The indoor scene is compared with the outdoor one. The idea of integratedrepresentation of the outdoor and the indoor scenes in CyberCity GIS is discusse d.

3D Engineering Model Retrieval Based on Enhanced Shape Distributions

To reuse and share the valuable knowledge embedded in repositories of engineering models for accelerating the design process, improving product quality, and reducing costs, it is crucial to devise search engines capable of matching 3D models efficiently and effectively. In this paper, an enhanced shape distributions-based technique of using geometrical and topological information to search 3D engineering models represented by polygonal meshes was presented. A simplification method of polygonal meshes was used to simplify engineering model as the pretreatment for generation of sample points. The method of sampling points was improved and a pair of functions that was more sensitive to shape was employed to construct a 2D shape distribution. Experiments were conducted to evaluate the proposed algorithm utilizing the Engineering Shape Benchmark (ESB) database. The experiential results suggest that the search effectiveness is significantly improved by enforcing the simplification and enhanced shape distributions to engineering model retrieval.

LOCALIZATION ALGORITHM BASED ON MINIMUM CONDITION NUMBER FOR WIRELESS SENSOR NETWORKS

During range-based self-localization of Wireless Sensor Network (WSN) nodes, the number and placement methods of beacon nodes have a great influence on the accuracy of localization. This paper proves a theorem which describes the relationship between the placement of beacon nodes and whether the node can be located in 3D indoor environment. In fact, as the highest locating accuracy can be acquired when the beacon nodes form one or more equilateral triangles in 2D plane, we generalizes this conclusion to 3D space, and proposes a beacon nodes selection algorithm based on the minimum condition number to get the higher locating accuracy, which can minimize the influence of distance measurement error. Simulation results show that the algorithm is effective and feasible.

3D Simulation of Storm Surge Disaster Based on Scenario Analysis

The occurrence of storm surge disaster is often accompanied with floodplain, overflow, dike breach and other complex phenomena, while current studies on storm surge flooding are more concentrated on the 1D/2D numerical simulation of single disaster scenario(floodplain, overflow or dike breach), ignoring the composite effects of various phenomena. Therefore, considering the uncertainty in the disaster process of storm surge, scenario analysis was firstly proposed to identify the composite disaster scenario including multiple phenomena by analyzing key driving forces, building scenario matrix and deducing situation logic. Secondly, by combining the advantages of k-ω and k-ε models in the wall treatment, a shear stress transmission k-ω model coupled with VOF was proposed to simulate the 3D flood routing for storm surge disaster. Thirdly, risk degree was introduced to make the risk analysis of storm surge disaster. Finally, based on the scenario analysis, four scenarios with different storm surge intensity(100-year and 200-year frequency) were identified in Tianjin Binhai New Area. Then, 3D numerical simulation and risk map were made for the case.