共查询到20条相似文献，搜索用时 734 毫秒
1.
Sabry F. El-Hakim Claus Brenner Gerhard Roth 《ISPRS Journal of Photogrammetry and Remote Sensing》1998,53(6):379-391
Creating virtual environment models often requires geometric data from range sensors as well as photometric data from CCD cameras. The model must be geometrically correct, visually realistic, and small enough in size to allow real-time rendering. We present an approach based on 3D range sensor data, multiple CCD cameras, and a colour high-resolution digital still camera. The multiple CCD cameras provide images for a photogrammetric bundle adjustment with constraints. The results of the bundle adjustments are used to register the 3D images from the range sensor in one coordinate system. The images from the high-resolution still camera provide the texture for the final model. The paper describes the system, the techniques for the registration of the 3D images, the building of the efficient geometric model, and the registration and integration of the texture with a simplified geometric model. 相似文献
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针对三维虚拟地球中实时GIS数据组织、管理与动态可视化的要求,设计了三维虚拟地球中移动对象的时空数据组织方法。提出了基于HR-tree扩展的时空索引方法,实现了对虚拟地球中移动对象的检索与查询,并基于三维虚拟地球平台对本文方法进行了实验,结果验证了本文方法的有效性和可行性。 相似文献
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《The Cartographic journal》2013,50(4):369-375
AbstractFor years, stereoscopy has been related to photogrammetry in topography. However, these methods are not efficient for virtual globes because the effect is only visible from one view point and this restricts interactivity. By using synthetic image techniques in order to generate stereo-paired images, we can produce visible effects from any view point. In this paper, we present a comparative study of stereoscopic techniques in virtual globes supported by a test carried out among 51 participants. Three devices were used: anaglyphs, an autostereoscopic screen and a quadbuffer system. The aim was to determine which one of the three devices causes a deeper feeling of immersion and which one can be more efficient in a virtual globe. Results show considerable differences between the quadbuffer system and the other devices. The mentioned system causes in the user a stronger feeling of depth and immersion in the virtual globe. 相似文献
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随着实景三维建设的不断推进,城市管理向立体化、精细化和数字化发展,建筑分层分户三维模型能够承载更详细精准的属性信息,并能叠加倾斜三维模型进行场景渲染,可以更好地服务于城市不动产三维管理、数字赋能社会治理等工作。本文以“萧山区数字赋能社会治理”项目建设为背景,探索和实现了基于不动产登记数据的建筑分层分户三维建模关键技术,形成了从全空间多源异构数据归集至城市全域建筑分层分户三维模型建设的一整套生产技术流程,为城市不动产三维管理、数字赋能社会治理等提供了有效的技术支撑和数据基础。 相似文献
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Sameer Saran Kapil Oberai Parag Wate Amol Konde Arnab Dutta Kavisha Kumar A. Senthil Kumar 《Journal of the Indian Society of Remote Sensing》2018,46(6):957-972
Virtual 3D city models are increasingly being used to model the realms of the real world for utilization in a number of applications related to environmental simulations including, urban planning, mapping the energy characteristics of buildings, noise mapping, flood modelling, etc. Apart from geometric and appearance/textural information, these applications have a requirement for complex urban semantics. Currently, a number of 3D standards are available in CAD, BIM and GIS related domains for the storage, visualization and transfer of 3D geospatial datasets. Initially, the 3D data models (such as COLLADA, VRML, X3D, etc.) were purely graphical/geometrical in nature and mainly used for visualization purposes. With the inclusion of thematic modules in OGC CityGML, the integration of geometry and semantics in a single data model paved the way for better sharing of virtual 3D city models. In spite of the availability of a wide range of 3D data standards, there are certain differences with respect to geometry, topology, semantics, LODs, etc., which complicates the integration of 3D geodata from heterogeneous sources. This paper serves to highlights the need for the innovative solutions with respect to the urban environmental related simulations primarily based on the use of virtual 3D city models. Four use cases are studied in this context namely, (1) urban solar potential estimation using CityGML models, (2) simulation of traffic noise level mapped on building walls from the urban road segments, (3) CityGML based 3D data models interoperability, and (4) 3D indoor logistics and subsurface utilities. However, for modelling majority of use cases, CityGML does not provide explicit thematic representations but provides support for extending the CityGML schema using Application Domain Extensions. In a nutshell, the study explores the semantic modelling capabilities of the CityGML for the transformation of native 3D virtual city models to one satisfying capabilities like semantic information and support towards interoperability. 相似文献
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《International Journal of Digital Earth》2013,6(1):107-118
Abstract The starting point of this paper is the idea that a comprehensive understanding of the earth and its systems calls for consideration of bygone views of the world. Creating facsimiles of antique globes in the form of digital globes provides a new opportunity to make such bygone world views accessible to a wide scientific audience. However, up to now, little practical experience in applying digital technology on globes has been made. Considering these attempts by thorough synopsis, this article deduces a comprehensive approach on virtual representations of antique globes that can be described by the superordinate concept of virtual representation. This concept comprises facilities of data acquisition of the original globe, ways of visualising the digitised globe and its final cartographic preparation. Applications that arise from this procedure are exemplified through both virtual hyperglobes and tactile hyperglobes. New findings on a 16th century earth globe are encouraging results of the presented virtual representation approach, which may offer a sustainable visualisation platform of interdisciplinary research. 相似文献
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提出了一种面向虚拟地球的海陆地形多尺度不规则三角网（triangulated irregular network,TIN）建模及球面快速可视化方法。利用贪心插入TIN表面简化算法构建海陆地形的离线TIN金字塔,并设计了一种高效的虚拟节点结构,对各级TIN构网实施无缝分割和分层分块存储。在利用离线TIN地形金字塔实现多尺度海陆TIN地形的快速检索和三维场景生成的基础上,通过一种接边关系编解码方案实时消除TIN地形渲染时的裂缝,最终实现多尺度海陆TIN地形场景的高效可视化。实验结果表明,该方法能显著减少海面渲染所需的面片数,并实现岛礁、海岸等破碎地形的高保真度表达,有效改善了传统虚拟地球系统采用规则格网（Gird）模式绘制海陆地形导致大量几何冗余和表达失真等缺陷。 相似文献
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Luana Valentini Maria Antonia Brovelli Giorgio Zamboni 《International Journal of Digital Earth》2014,7(4):336-350
In this article, we present the realisation of a multi-frame and multi-dimensional WebGIS that allows users to simultaneously analyse a specific portion of the Earth taking into account the historical information, too. Two graphical panels have been realised: one for the usual 2D view and one for a more realistic 3D view. Both panels display historical maps of the city, the current orthophoto and the digital topographical map. The 3D frame is based on NASA World Wind, an open source virtual globe from where 3D buildings are shown extruding the 2D shapes using their mean height. Thanks to a specifically designed graphical user interface, it is also possible to dynamically thematise the buildings on the globe according to different criteria (e.g. the construction time span) so that only the geometries fulfilling the request are turned on. Within the proposed application, a synchronisation between the two panels has been implemented, in order to maintain a constant alignment of the two viewers. The application is also open to the time dimension. In fact, assigning to each geometry two dates (e.g. ‘year of construction’ and ‘year of demolition’), it is possible to dynamically view how buildings have changed over time, both in their shape and height. Future developments of this work will concern the possibility of implementing a city model with a higher level of detail. 相似文献
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《International Journal of Digital Earth》2013,6(6):431-450
Typhoons are usually accompanied by strong winds, heavy rain, storm surges and other disastrous events, and they are the most severe weather phenomena in the western part of the North Pacific Ocean. Visualisation is a key technology for analysing and presenting climate simulations and observations together with related social and ecological data. Virtual globes are a logical platform for visualising such geospatial data via the Internet. To implement interactive visualisation of typhoon data within virtual globes, this study provides a 3D texture-mapping algorithm to render volume textures on a globe. In addition, a systematic framework is proposed in which a hierarchical octree-based multiresolution data structure is implemented to organise the large volume dataset, and a graphics processing unit-based dynamic interpolation approach is proposed to obtain a smooth effect. Finally, the structure is combined with a level of detail strategy to enable the rendering of dynamic volumetric data at an acceptable interactive frame rate. To demonstrate the capabilities of this framework, data for a simulated typhoon event were rendered in World Wind, an open-source virtual globe. The experimental results demonstrate that the application of the proposed strategies can result in an interactive visualisation performance that renders typhoon data on virtual globes. 相似文献
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City model enrichment 总被引：1，自引：0，他引：1
Philip D. Smart Jonathan A. Quinn Christopher B. Jones 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(2):223-234
The combination of mobile communication technology with location and orientation aware digital cameras has introduced increasing interest in the exploitation of 3D city models for applications such as augmented reality and automated image captioning. The effectiveness of such applications is, at present, severely limited by the often poor quality of semantic annotation of the 3D models. In this paper, we show how freely available sources of georeferenced Web 2.0 information can be used for automated enrichment of 3D city models. Point referenced names of prominent buildings and landmarks mined from Wikipedia articles and from the OpenStreetMaps digital map and Geonames gazetteer have been matched to the 2D ground plan geometry of a 3D city model. In order to address the ambiguities that arise in the associations between these sources and the city model, we present procedures to merge potentially related buildings and implement fuzzy matching between reference points and building polygons. An experimental evaluation demonstrates the effectiveness of the presented methods. 相似文献
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Three-dimensional (3D) reconstruction and texture mapping of buildings or other man-made objects are key aspects for 3D city landscapes. An effective coarse-to-fine approach for 3D building model generation and texture mapping based on digital photogrammetric techniques is proposed. Three video image sequences, two oblique views of building walls and one vertical view of building roofs, acquired by a digital video camera mounted on a helicopter, are used as input images. Lidar data and a coarse two-dimensional (2D) digital vector map used for car navigation are also used as information sources. Automatic aerial triangulation (AAT) suitable for a high overlap image sequence is used to give initial values of camera parameters of each image. To obtain accurate image lines, the correspondence between outlines of the building and their line features in the image sequences is determined with a coarse-to-fine strategy. A hybrid point/line bundle adjustment is used to ensure the stability and accuracy of reconstruction. Reconstructed buildings with fine textures superimposed on a digital elevation model (DEM) and ortho-image are realistically visualised. Experimental results show that the proposed approach of 3D city model generation has a promising future in many applications. 相似文献
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结合城市元胞自动机(CA)方法和虚拟现实(VR)技术,构建一个基于元胞的3维虚拟城市.首先建立基于元胞实体数据结构的城市CA模型,用以表示3维虚拟城市中建筑物的平面分布状态.通过CA模型生成一组城市建筑物的时空分布数据.然后利用DEM和DOM数据生成一个真实的3维地形,建立了不同种类的3维建筑模型库.最后通过程序调入城市3维建筑模型,根据元胞实体属性将模型布设于3维地形的相应位置,生成3维虚拟城市.Abstract： This paper unified the urban cellular automata method and the virtual reality technology to construct a three-dimension (3D) virtual city which was based on automata. First, constructing an urban CA model that is based on the data structure of cellular entities can present the plane distribution state of the building in the 3D virtual city. The CA model was used to compute a group of temporal layout data of buildings in the virtual city,Then,DEM and DOM data were used to generate real three-dimensional terrain and produce different type library about 3D building model. Finally, The program was used to load and lay the 3D buildings to the corresponding position in the 3D virtual terrain to obtain a 3D virtual city, according to the cellular entity attribute. 相似文献
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Wumeng Huang 《International Journal of Digital Earth》2018,11(9):939-955
3D city models, which are important items of content on the virtual globe, are characterized by complicated structures and large amounts of data. These factors make the visualization of 3D city models highly dependent upon the performance of computer hardware. Thus, achieving the efficient rendering of 3D city models using different hardware performance levels represents one of the key problems currently facing researchers. This paper proposes a time-critical adaptive visualization method that first estimates the possible rendering time for each model according to the data structure of the model in addition to the CPU/GPU performance of the computer. It then dynamically adjusts the rendering level for each model based on the results of an estimation of the rendering time to ensure that the final scene can be completed within a given time. To verify the effectiveness and flexibility of this method, it is applied using different computers. The results show that the adaptive visualization method presented in this paper not only can adapt to computers with different levels of performances but also demonstrates an obvious improvement in the time estimation precision, visual effects, and optimization speed relative to existing adaptive visualization methods. 相似文献
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In this paper we introduce analytical three-dimensional (3D) views as a means for effective and comprehensible information delivery, using virtual globes and the third dimension as an additional information carrier. Four case studies are presented, in which information extraction results from very high spatial resolution (VHSR) satellite images were conditioned and aggregated or disaggregated to regular spatial units. The case studies were embedded in the context of: (1) urban life quality assessment (Salzburg/Austria); (2) post-disaster assessment (Harare/Zimbabwe); (3) emergency response (Lukole/Tanzania); and (4) contingency planning (faked crisis scenario/Germany). The results are made available in different virtual globe environments, using the implemented contextual data (such as satellite imagery, aerial photographs, and auxiliary geodata) as valuable additional context information. Both day-to-day users and high-level decision makers are addressees of this tailored information product. The degree of abstraction required for understanding a complex analytical content is balanced with the ease and appeal by which the context is conveyed. 相似文献
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三维城市模型的研究与实践(英文) 总被引：3，自引：0，他引：3
The way we interact with spatial data has been changed from 2D map to 3D Virtual Geographic Environment (VGE). Three-dimensional
representations of geographic information on a computer are known as VGE, and in particular 3D city models provide an efficient
way to integrate massive, heterogenous geospatial information and georeferenced information in urban areas. 3D city modeling
(3DCM) is an active research and practice topic in distinct application areas. This paper introduces different modeling paradigms
employed in 3D GIS, virtual environment, and AEC/FM. Up-to-date 3DCM technologies are evolving into a data integration and
collaborative approach to represent the full spatial coverage of a city, to model both aboveground and underground, outdoor
and indoor environments including man-made objects and natural features with 3D geometry, appearance, topology and semantics.
Supported by the National Natural Science Foundation of China ( No. 40871212, No. 40671158), the Leading Academic Discipline
Project of Shanghai Educational Committee( No.J50104). 相似文献
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三维城市模型的多细节层次描述方法 总被引：11，自引：2，他引：11
以仿唐建筑群的逼真三维模型为例,介绍了一种实用的LOD模型细节层次规划及其精细程度的确定方法,以及配套的数据生产工艺,为建立具有几何上的高精度和视觉上的高逼真度的三维城市模型提供了一条有效的途径。 相似文献
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Sandra Loch-Dehbi Lutz Plümer 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(2):177-187
This paper presents a novel approach to automated geometric reasoning for 3D building models. Geometric constraints like orthogonality or parallelity play a prominent role in man-made objects such as buildings. Thus, constraint based modelling, that specifies buildings by their individual components and the constraints between them, is a common approach in 3D city models. Since prototyped building models allow one to incorporate a priori knowledge they support the 3D reconstruction of buildings from point clouds and allow the construction of virtual cities. However, high level building models have a high degree of complexity and consequently are not easily manageable. Interactive tools are needed which facilitate the development of consistent models that, for instance, do not entail internal logical contradictions. Furthermore, there is often an interest in a compact, redundancy-free representation. We propose an approach that uses algebraic methods to prove that a constraint is deducible from a set of premises. While automated reasoning in 2D models is practical, a substantial increase in complexity can be observed in the transition to the three-dimensional space. Apart from that, algebraic theorem provers are restricted to crisp constraints so far. Thus, they are unable to handle quality issues, which are, however, an important aspect of GIS data and models. In this article we present an approach to automatic 3D reasoning which explicitly addresses uncertainty. Hereby, our aim is to support the interactive modelling of 3D city models and the automatic reconstruction of buildings. Geometric constraints are represented by multivariate polynomials whereas algebraic reasoning is based on Wu’s method of pseudodivision and characteristic sets. The reasoning process is further supported by logical inference rules. In order to cope with uncertainty and to address quality issues the reasoner integrates uncertain projective geometry and statistical hypothesis tests. Consequently, it allows one to derive uncertain conclusions from uncertain premises. The quality of such conclusions is quantified in a way which is sound both from a logical and a statistical perspective. 相似文献
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The graphical representation and interactive manipulation of accurate three dimensional (3D) models of reality is rapidly becoming an inescapable necessity for many applications of geographical information systems (GIS). There are many problems and difficulties that must be overcome in order to facilitate such 3D models. Can accurate measurements, at sufficient resolution and using affordable resources, be obtained? Will application software usefully process, in all aspects, models of the real world, held in full 3D? Can a topology of containment, adjacency and contiguity in 3D be integrated into the conventional procedural and recording functionality of two dimensional (2D) GIS and still provide workable spatial analysis tools? A 3D GIS applied to an urban environment should maintain a model that would typically consist of solid representations of individual buildings, roads and utilities, providing both external and internal detail, all assigned to a suitable digital terrain model (DTM). The particular 3D application considered here addresses the need for accurate reconstruction of historical urban buildings. The creation, manipulation and exploration of such models is often referred to as “virtual heritage”. Much of this paper describes an effective methodology, called the Phoenix algorithm, requiring only a single image of an urban object, for the construction of 3D models of buildings at high resolution. The development of this algorithm is discussed and the results obtained from it are compared with those obtained using traditional 3D capture techniques. An outline of further potential GIS applications is presented. 相似文献