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讨论了城镇绿地树种识别数学描述符的设计思想和方法。本着具有确切的物理意义、几何意义或植物生态
学意义以及分割阈值具有环境不变性的原则,设计了归一化阴影指数、饱和度明度相对差、相对边缘点数、相对暗
细节密度、相对骨架密度和加权平均冠径等14个分别涉及波谱、纹理和形状特征的新描述符。经过样本统计分析和
遥感图像实例测试,证明这些描述符在城镇绿地树种识别方面比经典描述符具有更好的针对性和更强的适应性。此
外,本文还讨论并测试了红色欠饱和像元补偿集的提取方法,以及基于cell分割或分类的方法。对于城镇绿地树种
分类问题,在决策树分类输入矢量中,使用本文的描述符组合误分率为5.8%,相比传统的分色亮度组合(误分率为
25.9%)有明显改进。 相似文献
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New development in urban planning, cityscape, real estate management and the like, calls for new demands for 3D city model. There are so many objects in 3D city model such as building, river, road, and so on. The building model is very important in 3D city model. In recent years, a lot of research work about visualization has been done. In our opinions, visualization is only a part of 3D city model, while interactive operation about buildings is rather important as well. In order to implement interactive operation (create, edit, query, etc.), good data structure and model must be developed. 相似文献
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YANG BishengLI QingquanLI Deren YANG Bisheng Doctoral Candidate National Laboratory for Information Engineering in Surveying Mapping Remote Sensing WTUSM Luoyu Road Wuhan China 《地球空间信息科学学报》1999,2(1):109-114
New development in urban planning, cityscape, real estate management and the like, calls for new demands for 3D city model. There are so many objects in 3D city model such as building, river, road, and so on. The building model is very important in 3D city model. In recent years,a lot of research work about visualization has been done. In our opinions,visualization is only a part of 313 city model, while interactive operation about buildings is rather important as well. In order to implement interactive operation (create , edit, query,etc. ), good data structure and model must be developed. 相似文献
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Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2‐D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3‐D approach. This study presents a new 3‐D solar radiation model for urban areas represented by 3‐D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3‐D vector data representing complex urban environments. The calculation procedure is based on the combined vector‐voxel approach segmenting the 3‐D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces. 相似文献
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随着电子产品的普及和互联网发展,人们习惯性地将照片上传到主流图片分享网站和社交媒体。这些照片很多都没有地理坐标或者仅有模糊的位置信息。如果互联网上任意来源的电子照片能被恢复出真实地理位置,它们将可以应用在城市建设、城市景观分析和犯罪追踪等很多方面。本文提出了一种互联网众筹照片的三维重建定位技术,该技术将结构化组织的街景数据作为参考数据集,使用三步走策略：图像检索粗定位、图像匹配细筛选和三维重建精定位,来给不明来源的众筹照片附上精确的地理标签。本文通过摄影测量原理恢复待查询照片周围的三维空间信息,较之前Zamir和Shah的方法,定位精度中值从256.7 m提升到69.0 m,平均值从350.4 m提升到206.0 m,在50 m精度要求下的照片数量占比从17.2%提升到43.2%。另一个发现是在重建误差成因方面,待查询照片的相机距离主拍摄目标越近,定位总误差越小。本文所提出的照片定位技术提供了灵活的参数,使其应用范围不仅仅局限于小区域,也可以扩大至城市、国家尺度。 相似文献
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一种支持机场反劫机事件的3DCM的设计与实现 总被引：1，自引：0，他引：1
本文以机场反劫机为例设计了一种城市重要目标反恐战场环境的三维可视化和查询工具。该工具将虚拟环境中的地理要素以三维和二维的图形、图像表达出来,主要采用边界模型作为建立3维目标的数据结构,并利用DDE技术连接三维场景中的景物和二维GIS的关系数据库存储属性并实现查询功能。其特点是利用简单的DDE方式实现了3D场景数据和属性数据双向查询,充分利用了已经建成的2DGIS的成熟功能和现有资源。 相似文献
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针对不同姿态下的三维等距部分模型与完整模型对应关系计算问题,提出了一种结合局部函数映射和局部流形谐波(localized manifold harmonics,LMH)算子计算三维模型特征描述符并构建模型间对应关系的新方法。首先,通过改进的Laplace算子的谱分解构造局部基产生LMH算子,并计算模型的特征描述符;其次,通过局部函数映射理论构建部分模型与完整模型间的初始对应关系;然后,交替迭代计算部分模型与完整模型间的稠密对应关系;最后,利用贪心算法优化对应关系直至收敛。实验结果表明,以局部流形谐波产生的新算子与局部函数映射方法计算得到的稀疏对应关系为基础,能构建更为准确的稠密对应关系,并在一定程度上减少等距误差。和已有算法相比,采用LMH算子构建的特征描述符比由Laplace-Beltrami算子构建的特征描述符更能体现出部分模型的本征属性,计算出的对应关系也更加准确。 相似文献
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《ISPRS Journal of Photogrammetry and Remote Sensing》1999,54(4):263-272
In this paper, we address the problem of content-based image retrieval using queries on shape and topology. We focus on the particularities of image databases encountered in typical topographic applications and present the development of a spatial data management system that enables such queries. The query requires user-provided sketches of the shape and spatial configuration of the object (or objects) which should appear in the images to be retrieved. The objective of the search is to retrieve images that contain a configuration of objects sufficiently similar to the one specified in the query. Our approach combines the design of an integrated database with the development of a feature library and the necessary matching tools. In this paper, we present our overall scheme, introduce some individual database components, and provide some implementation results. 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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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 world’s rising urban density expansion has resulted in a proliferation of attempts to efficiently use space and a higher level of spatial complexity in metropolitan areas. 3D geospatial data models are increasingly being embraced to facilitate communicating the spatial dimensions of complex built environments in different applications. For example, the use of 3D models in land administration systems has been recognized as a good approach for communicating the spatial complexity of legal spaces within multi‐storey buildings. The spatial extent of legal space—to which rights, restrictions and responsibilities relate in a 3D digital cadastre—needs to be accurately defined and geometrically closed; watertight. Therefore, this study aims to address the challenges regarding checking the closure of diverse 3D legal spaces and engage several techniques to formulate the watertight concept for cadastre. The research’s methodology is built on a 3D polyhedral surface using a half‐edge data structure. A primitive check is employed to assess the spatial consistency of lower‐dimensional primitives of 3D objects. Subsequently, advanced closure checks ensure the closure of volumetric legal spaces represented by 2‐manifold and non‐2‐manifold data models. The article concludes that, by adopting the proposed approaches, the internal spatial consistency of legal spaces in urban land administration will be certified. 相似文献
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高分辨率遥感影像目标形状特征多尺度描述与识别 总被引：1，自引：0，他引：1
在高分遥感影像中,同类地物目标形状具有多样性,单一尺度或单一形状模版不足以描述同类目标的形状。本文利用小波变换和Fourier描述子构建了一种目标形状的多尺度描述模型,并基于该模型给出了一种新的面向对象的高分遥感影像目标识别方法。从上到下,该模型采用尺度依次减小的小波近似系数对原始形状进行近似表示,并利用Fourier描述子对其进行定量描述。利用语义规则综合考虑多个尺度下的识别结果,得到最终识别结果,减小小尺度下分割目标破碎和大尺度下小目标无法识别造成的影响,提高识别精度。基于本文方法分别对高分遥感影像中的飞机和建筑物进行识别,对比实验表明,该方法具有较高识别精度。 相似文献
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面向地质建模的三维体元拓扑数据模型研究 总被引：27，自引：0，他引：27
在对地质对象的基本特征和计算机三维地质建模的基本要求进行讨论的基础上，提出了面向对象的三维体元拓扑数据模型。在该数据模型中，用面向对象的方法将地质对象抽象为点、线、面、体，体类又进一步划分为复合体、复杂体、简单体和体元四类。对所有对象类设计了12种拓扑关系和相应的数据结构。 相似文献
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Texture mapping generates photorealistic representations of three‐dimensional (3D) geometric objects and enhances the spatial perception of areas of interest. Over the past two decades, even though various approaches for 3D urban models have been investigated, their use has been limited because of the lack of spatial accuracy, details, and the complex processes. It is difficult to maintain highly detailed texture information without using a hybrid of aerial image and ground‐based imaging techniques, which are costly. Furthermore, it is hard to develop a fully automated process for 3D urban mapping that achieves high spatial accuracy. With regard to the issues, this research aims to develop a semi‐automated process for 3D building models that would help image‐based approaches. It helps acquire qualified texture information and improve the appearance of building façades in a large city. In particular, this research first investigates an optimal overlap of consecutive aerial images that generates sufficient information to texture each façade, thus making this process more cost‐effective. Second, this research develops an application to semi‐automatically build 3D buildings and textured 3D buildings. The application is developed in C++. The textured 3D building models are quantitatively and qualitatively assessed to determine the usability of the semi‐automated process. 相似文献