共查询到20条相似文献，搜索用时 15 毫秒
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给出了利用CityGML模型自动构建三维封闭建筑体的基本框架和流程。充分利用已有的CityGML数据,分析其与三维封闭建筑体的语义关联和差别,奠定利用CityGML构建三维封闭建筑体的理论基础;从构建三维封闭建筑体所需几何数据出发,根据语义关联从CityGML中提取相应的几何数据,构建符合三维封闭建筑体要求的几何对象,满足三维立体规划和审批、核查的空间数据需要,进而弥补传统地籍数据采集方式的不足。 相似文献
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地形信息的LoD建模及精度分析 总被引：5，自引：0，他引：5
对细节层次模型(LoD模型)不同层次之间的精度进行研究.提出用于分层的简化比率概念,建立表示LoD不同层次精度的分辨率误差模型,选取5种典型地貌区域进行实验,得到不同地貌区域的误差拟合公式.根据这些公式,可内插得到各种分辨率比率的误差.同时,利用逆公式,又能由误差确定相应的分辨率比率.最后,对不同地貌类型不同化简算法的模型化简误差进行分析研究.研究成果为评价LoD模型精度提供新的方法,也为简化DEM模型时选择适宜的分辨率提供科学依据. 相似文献
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面向目标的栅格矢量一体化三维数据模型 总被引：1，自引：0，他引：1
首先对现有的三维空间数据模型进行了讨论 ,分析了栅格、矢量和混合数据模型的特点 ,提出了一种面向目标的栅格矢量一体化数据模型。该模型将栅格数据以矢量方式进行组织 ,从而同时具有矢量和栅格数据模型的优点 ,也克服了目前普遍应用的混合模型所存在的缺点。还提出了一种三维空间的三级栅格划分和行次序编码方法。该方法存储空间小 ,便于快速索引和计算。最后 ,给出了具体的数据结构 相似文献
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单像空间后方交会可描述为非线性最小二乘问题，不可导、法方程系数矩阵病态以及陷入局部极值是造成其数值过程不收敛的主要原因。不同地区的控制点空间分布不具相似性，若把同一地区同一组控制点之下数张已知外方位元素的像片看作一个样本集，则在给定每个外方位元素初值的前提下，可通过监督学习方法求取外方位元素的整体下降方向；而对于单像空间后方交会中因前述原因不收敛的情况，则可采用整体下降方向近似解算。以此为出发点，提出一种单像空间后方交会求解的监督学习方法，主要过程是:①训练阶段，利用监督学习过程，对同一测区内不同姿态像片所组成的样本集进行整体外方位元素的求解，得到该测区外方位元素的整体下降方向集合；②测试阶段，对该测区的任意像片，给定外方位元素的初值，直接采用训练阶段得到的整体下降方向集合进行外方位元素的迭代求解。对比试验表明，该方法在数值过程收敛性与初值依赖性上均表现出较强的优势，并能克服欧拉角法因法方程系数矩阵病态而无法收敛的情况。 相似文献
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针对控制点获取较困难地区卫星影像定位精度不高的情况,对直线特征作为控制信息提升卫星影像定位精度进行了研究。以"像方直线上任意一点必然位于物方直线和投影中心所构成的平面"作为几何约束条件,通过对直线的参数化表示,建立了基于直线特征的共面模型;在该模型基础上,针对航天传感器的成像特点,分析建立了8标定参数的内方位元素模型和简化的外方位元素模型,最终构建了直线特征约束的卫星影像自检校平差模型。利用资源3号(ZY-3)卫星获取的华盛顿地区数据对构建的平差模型进行实验验证。结果表明,该模型能够解决缺乏地面控制点地区影像定位精度差的问题,可达到与常规自检校平差相同量级的精度。 相似文献
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Christoph Blut Timothy Blut Jörg Blankenbach 《International Journal of Digital Earth》2019,12(1):25-42
CityGML, a semantic information model for digital/virtual city models has become quite popular in various scenarios. While the data format is still actively under development, it is already supported by different software solutions, especially GIS-based desktop applications. Mobile systems on the other hand are still neglected, even though the georeferenced objects of CityGML have many application fields, for example, in the currently popular area of location-based Augmented Reality. In this paper we present an independent multi-platform CityGML viewer, its architecture and specific implementation techniques that we use to realize and optimize the process of visualizing CityGML data for use in Augmented Reality. The main focus lies in improving the implementation on mobile devices, such as smartphones, and assessing its usability and performance in comparison to web-based approaches. Due to the constrained hardware resources of smartphones, it is a particular challenge to handle complex 3D objects and large virtual worlds as provided by CityGML, not only in terms of memory and storage space, but also with respect to mobile processing units and display sizes. 相似文献
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基于语义的多细节层次3维房产模型 总被引：5，自引：2，他引：3
针对2维房产管理中的产权重叠、表达不完全和建筑物室内外一体化管理难题,在综合分析3维房产数据的对象类型及其应用特性的基础上,从概念层次提出了一种基于语义的多细节层次3维房产模型。该模型通过空间与产权的语义描述,对3维房产管理对象间的多细节层次关系进行一体化表达,特别是实现了对建筑物内部的房产空间关系表达,有利于明晰内部空间(户)的产权划分及各房产对象间的产权关联,为建立产权明晰与室内外综合管理的真3维房产应用提供了理论依据。 相似文献
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基于几何元素的三维景观实体建模研究 总被引：1，自引：0，他引：1
在分析已有国内外研究成果的基础上 ,提出了基于几何元素的 3DCM空间数据模型。实验证明 ,该模型能较精确地表达 3DCM中各类景观实体及其空间关系。 相似文献
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The determination of the attitude, the position and the intrinsic geometric characteristics of the camera is recognised as the fundamental photogrammetric problem. It can be summarised as the determination of camera interior and exterior orientation parameters, as well as the determination of 3D coordinates of object points. The term "exterior orientation"of an image refers to its position and orientation related to an exterior (object space) coordinate system. Several methods can be applied to determine the parameters of the orientation of one, two or more photos. The orientation can be processed in steps (as relative and absolute orientation) but simultaneous methods (such as bundle adjustments) are now available in many software packages. Several methods have also been developed for the orientation of single images. They are based in general on geometric and topological characteristics of imaged objects.
This paper presents a survey of classical and modern methods for the determination of the exterior parameters in photogrammetry, some of which are available as software packages (with practical examples) on the Internet. The methods presented are classified in three principal groups. In the first, a selection of approximate methods for applications that do not require great accuracy is presented. Such methods are also used to calculate values required for iterative processes. In the second group, standard point–based methods derived from collinearity, coplanarity or coangularity conditions are briefly reviewed, followed by line–based approaches. The third group represents orientation methods based on constraints and on concepts of projective geometry, which are becoming of increasing interest for photogrammetrists. In the last section, the paper gives a summary of existing strategies for automatic exterior orientation in aerial photogrammetry. 相似文献
This paper presents a survey of classical and modern methods for the determination of the exterior parameters in photogrammetry, some of which are available as software packages (with practical examples) on the Internet. The methods presented are classified in three principal groups. In the first, a selection of approximate methods for applications that do not require great accuracy is presented. Such methods are also used to calculate values required for iterative processes. In the second group, standard point–based methods derived from collinearity, coplanarity or coangularity conditions are briefly reviewed, followed by line–based approaches. The third group represents orientation methods based on constraints and on concepts of projective geometry, which are becoming of increasing interest for photogrammetrists. In the last section, the paper gives a summary of existing strategies for automatic exterior orientation in aerial photogrammetry. 相似文献
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Albert K. Chong 《The Photogrammetric Record》2004,19(108):296-310
Generally, a low-cost image-based motion study system consists of a set of two or more video imaging cameras and a set of object space control targets. The control targets are required to provide for the computation of exterior parameters of the video frames of objects in motion. Subsequently, the computed exterior orientation parameters are used to compute the position of the motion targets. In general, the accuracy of the motion data is dependent largely on the accuracy of the 3D coordinates of the control targets, the computed camera and lens parameters and the frame rate of the camera. Obviously, it is difficult to improve the frame rate of a low-cost camera; however, the other factors may be optimised analytically. Optimising the accuracy of the control targets is a straightforward process and is discussed briefly in the paper. Optimising the computed camera and lens parameters was the main focus of the research. Consequently, the paper provides the detail of the developed optimising technique. The results show that an optimal principal distance and other lens parameters can be determined by analysing the error of a set of highly accurate object distances. The evaluation shows that the accuracy of the video motion study system can be improved by as much as six times or a reduction of scaling error from 1·06 to 1·01. 相似文献
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针对大场景考古挖掘现场的三维重建情况,选取半全局匹配策略作为研究基础,设计了一种基于附加控制点约束的半全局匹配算法进行序列影像密集匹配。将稀疏匹配中的特征提取和匹配技术用于提取初始特征,并由这些初始特征转化的同名特征点,生成视差空间影像中的视差控制点,以此作为一种可靠的约束,提高其密集匹配的精度。同时,采用影像分块的策略,将原始大核线影像分成若干对小核线影像,进行密集匹配,以达到提高计算效率,改善计算结果的目的。实验证明,该方法可实现大面积考古挖掘现场的快速三维重建,并且能够在进行文物形态三维重建的同时获取挖掘现场文物分布的正射影像平面图,为准确记录挖掘现场文物分布位置及考古发掘、调查及遗址保护规划编制等提供科学依据。 相似文献
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基于倾斜摄影测量的三维建模已成为城市级实景三维建设的发展趋势。在城市三维模型中,由于植被表面不平整,需要用大量的三角面来刻画,但这并不是实景三维数据记录和表达的重点,并且大量的数据会给模型展示和应用带来很大的困难。因此,本文提出了一种顾及地物类别的倾斜摄影三维模型简化方法。首先,计算三维模型的纹理信息和几何信息,结合马尔可夫随机场(MRF)顾及空间一致性的优点提取植被;然后,采用二次误差测度(QEM)算法简化特定的植被区域;最后,对简化后的白膜模型进行纹理重映射。试验结果表明,本文方法能够准确提取并有效简化植被区域,纹理重映射的结果在外观上也与原始模型相差无几,取得了预期的良好效果。 相似文献
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地面三维激光扫描技术可以快速地采集目标物表面海量点云数据,利用点云能够准确重建空间三维模型。本文基于完全不同形状的两组点云数据,分别采用三角网格法和提取特征线法两种不同建模方法进行实验,完成模型重建,取得较好的效果。同时探讨了点云处理和模型重建的关键问题,为工程生产提供借鉴。 相似文献
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网络中移动对象的2维时空数据模型 总被引：2，自引：0，他引：2
提出一种新的2维网络中移动对象的时空数据模型2-Dimensional Spatio-Temporal data model for Mov-ing Objects in Network(2DSTMON)。2DSTMON时空数据模型基于线性参考思想,将3维空间中的轨迹数据转换到2维空间中进行存储和管理,并采用运动矢量的数据更新方式,具有较小的数据量和较低的更新代价。最后,利用ESRI的ArcEngine实现并验证2DSTMON时空数据模型。 相似文献
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Street view (panoramic view) services have begun to shift from PC platforms to mobile smart devices. Considering the capabilities of smart terminal devices, a 360° spherical level of detail (LoD) model for mobile street view services that renders panoramic images on the inner surface of a sphere via LoD is proposed in this article. Panoramic images are segmented into tiles and organized in a pyramid tile structure for LoD rendering to improve the rendering efficiency of the proposed model. A projection model between panoramic images and the spherical surface is presented to map the panoramic tiles on the spherical graticule. A street view‐rendering algorithm of panoramic images is proposed with the rendering function of OpenGL for Embedded Systems (OpenGL ES). A street view service app running on Android, based on the proposed approach, is implemented to assess two aspects of the panoramic view model, namely visualization effect and efficiency. Experiment results reveal that the 360° spherical LoD model of the panoramic image can display 3D street view scenes better than the cubic panoramic view model. The proposed model also has an excellent 3D visualization effect and high‐efficiency rendering ability for mobile street view services. Therefore, it is applicable in large‐scale mobile street view services both online and offline and in augmented reality navigation. 相似文献
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将对偶四元数应用于摄影测量中,提出了一种基于单位对偶四元数的航空影像区域网平差解算方法。相比于常规的平差方法和四元数方法,该算法的最大特点是将影像的摄站位置和姿态以一个单位对偶四元数整体表示,从而构建基于对偶四元数的区域网平差模型,并采用具有约束条件的参数平差进行解算。利用两个地区不同比例尺的实际航空影像数据进行实验,结果表明,该算法的平差精度与常规的区域网平差方法相当,对影像比例尺及控制点的数量与分布的需求也与常规的平差方法基本相同,为对当前轻小平台获取航空影像进行摄影测量处理提供了一条新的技术思路。 相似文献