共查询到20条相似文献，搜索用时 31 毫秒
1.
Jiangfeng She Xinchi Li Yaqian Chen Junzhong Tan 《International journal of geographical information science》2019,33(10):2033-2054
Adding building labels greatly improves the recognizability of buildings and the readability of three-dimensional (3D) city scenes. However, building label placement is much more complex in 3D scenes than in two-dimensional (2D) maps. The annotation effect is influenced by the attributes of the 3D label, building visibility, and the spatial relationship between the building and viewpoint. In this context, automatically generating building labels for 3D scenes during interactions requires highly complex computations. By contrast, evaluating candidate labels and then selecting the suitable label for each building can be effectively implemented. This paper introduces an approach for labeling buildings in 3D scenes based on evaluations of label candidates. The proposed method predefines a candidate label set for each building. These candidates are then evaluated in terms of their attributes and the relationship between the labels and viewpoint at runtime. The best candidate label, or a situational alternative for each building, is then placed in order of comprehensive label priority to avoid annotation conflicts. A series of experiments demonstrate that this method effectively enhances the correlation of labels and buildings, improves interactive efficiency, and realizes a viable global label layout. 相似文献
2.
Steven Van Dijk Marc Van Kreveld Tycho Strijk Alexander Wolff 《International journal of geographical information science》2013,27(7):641-661
The cartographic labelling problem is the problem of placing text on a map. This includes the positioning of the labels, and determining the shape in the case of line and area feature labels. There are many rules and customs that describe aspects of good label placement, like readability and clear association. This paper gives a classification of most label placement rules, and formalizes them into a function that can serve as a quality measure for label placement. If such a function is implemented, it allows comparison of the output of different label placement programs. We give a simple and a more refined example of the quality function. 相似文献
3.
Arko Lucieer Menno-Jan Kraak 《International journal of geographical information science》2013,27(5):491-512
In this study, we propose, describe, and demonstrate a new geovisualization tool to demonstrate the use of exploratory and interactive visualization techniques for a visual fuzzy classification of remotely sensed imagery. The proposed tool uses dynamically linked views, consisting of an image display, a parallel coordinate plot, a 3D feature space plot, and a classified map with an uncertainty map. It allows a geoscientist to interact with the parameters of a fuzzy classification algorithm by visually adjusting fuzzy membership functions and fuzzy transition zones of land-cover classes. The purpose of this tool is to improve insight into fuzzy classification of remotely sensed imagery and related uncertainty. We tested our tool with a visual fuzzy land-cover classification of a Landsat 7 ETM+ image of an area in southern France characterized by objects with indeterminate boundaries. Good results were obtained with the visual classifier. Additionally, a focus-group user test of the tool showed that insight into a fuzzy classification algorithm and classification uncertainty improved considerably. 相似文献
4.
本文着重阐述了微机图形系统中图面动态整饰的应用研究，其中包括对图面内容、图名、图例，以及内、外图廓的整饰。图形系统的图面动态整饰，主要是针对计算机图形学的研究对象、其整饰的内容以及现在多数微机图形系统普遍存在的问题，采用不同的数学算法及模型，研究图面整饰的技巧和方法。图面内容的动态整饰是全文的重点，它主要包含：多要素地图的依比例分级动态显示、汉字注记的变体、注记的配置整饰和注记的沿线性要素动态分布显示等。因此，图形系统中微机制图整饰对其传统工艺进行革新，使人们从繁锁复杂的工艺劳动中解脱出来，极大地提高了工作效率，同时改进了图形系统的制图工艺。 相似文献
5.
Zhou Guo 《International journal of geographical information science》2020,34(4):661-680
ABSTRACTPoint cloud classification, which provides meaningful semantic labels to the points in a point cloud, is essential for generating three-dimensional (3D) models. Its automation, however, remains challenging due to varying point densities and irregular point distributions. Adapting existing deep-learning approaches for two-dimensional (2D) image classification to point cloud classification is inefficient and results in the loss of information valuable for point cloud classification. In this article, a new approach that classifies point cloud directly in 3D is proposed. The approach uses multi-scale features generated by deep learning. It comprises three steps: (1) extract single-scale deep features using 3D convolutional neural network (CNN); (2) subsample the input point cloud at multiple scales, with the point cloud at each scale being an input to the 3D CNN, and combine deep features at multiple scales to form multi-scale and hierarchical features; and (3) retrieve the probabilities that each point belongs to the intended semantic category using a softmax regression classifier. The proposed approach was tested against two publicly available point cloud datasets to demonstrate its performance and compared to the results produced by other existing approaches. The experiment results achieved 96.89% overall accuracy on the Oakland dataset and 91.89% overall accuracy on the Europe dataset, which are the highest among the considered methods. 相似文献
6.
In every map, irrespective of its theme, objects are represented at a reduced scale. Map contents do not decrease proportionally to the reduction of the map size. Usually an increasing density of the map contents occurs at smaller scales. That is where the generalization plays an important role. Generalization is the process of creating a legible map at a given scale from a more detailed geographical dataset. It is done in such a manner that the character or essence of the original features is retained at successively smaller scales. Though the purposes and benefits of generalization are manifold it is indeed a complex decision-making process which must be intelligently steered by goals and rules from the geographical application domain such that the generalized representation conveys knowledge consistent with the reality. In recent past, lot of work has been done in 2D generalization (Beard, 1991; Weibel, 1995; Bealla, 1995; Ruas and Plazanet, 1996; Sarjakoski and Kilpeläinen, 1999) which defines a set of operations to be performed with the goal to achieve the similar results to those from manual generalization. But 3D generalization is altogether perceived differently. A given 3D urban area mostly consists of roads and buildings. These buildings are of different styles and features. Further the city area may be viewed from different angles and at different heights. So generalization in general and aggregation in particular must deal with all these issues. In this paper, an effort has been made to address these issues. 相似文献
7.
王殷行 《地理与地理信息科学》2008,24(6)
提出GIS多边形倒金字塔模型,拓展了模型能够支持的数据结构与适用范围,使其可以应用于普通GIS电子地图中,为采用预生成不同比例尺图面多分辨率表达无极比例尺图形显示技术提供了模型支持,并给出了建模方法,使普通GIS多边形的无极比例尺显示可以依据精度标准进行局部更新和无冗余存储。 相似文献
8.
虚拟旅游系统是利用三维GIS、虚拟现实与网络等技术构建的面向旅游业的网络虚拟现实系统平台。在整个虚拟旅游系统构建中,最基础也是最重要的部分是虚拟旅游景观的实现,它关系着虚拟景观的展示效果、显示速度以及空间分析、情景模拟等各项功能的实现。本文基于虚拟旅游景观的特点及实现难点,使用ArcGIS和3DSMax分别建立具有不同形态特征的虚拟地面模型和虚拟地物模型,将所有模型转换为VRML文件格式并进行优化,不仅有效融合了虚拟地面模型和虚拟地物模型,并且兼顾了模型的逼真度和显示速度。本文提出了一套虚拟旅游景观的设计方案、关键技术,并通过圆明园遗址公园虚拟旅游景观的实现,验证了其可行性。本研究对于虚拟旅游的发展具有积极的参考意义,对于我国众多旅游景区虚拟旅游系统的研发具有技术的应用性和可推广性。 相似文献
9.
中山站至DomeA冰川学考察断面是国际ITASE计划的核心断面之一。首次利用GIS开展了该断面的数据处理与信息提取 ,采样点的布设与管理。介绍了ADD数字地图拼接与裁剪 ,野外数据和BEDMAP数据地理坐标投影变换的方法。利用ArcView内插等高线方法对GPS导航仪高程数据进行了校正。沿考察路线提取了BEDMAP的冰下基岩高程和冰厚度数据 ,以及冰盖表面的坡度与坡向数据。指出应进一步开展该断面以及兰伯特冰川盆地GIS应用研究。 相似文献
10.
《The Journal of geography》2012,111(5):241-245
Abstract Construction of raised-relief maps by students in middle school to high school is a rewarding “hands-on” experience. A major feature of this project is that materials are readily available, inexpensive and manageable by students themselves. Tracing from topographic maps on to inexpensive, easily-carved materials like cardboard or foam-core board involves the student in map interpretation techniques. Concepts such as interpreting elevations from contour lines, recognizing symbolization on a map, seeing raised-relief as representing “the lay of the land,” understanding map scale, and recognition of color in representation of elevations are part of this experience. Carving and construction of the raised-relief map give the student an appreciation of topographic features in 3-D. The finished model can serve as a display and learning tool for the future. 相似文献
11.
无人机遥感能够获取高精度、高分辨率的冰川表面三维形态,有助于揭示冰川的运动和消融变化,现已成为冰川变化监测的重要技术支撑。针对无人机高分辨率影像能够有效识别表碛覆盖型冰川表面细节特征点的优势,本文引入金字塔影像集和最小二乘匹配方法联合开展特征点的追踪,用以实现冰川表面特征点三维位移场提取和动态变化分析。以贡嘎山贡巴冰川冰舌区作为典型研究区域,利用高分辨率无人机影像生成消融期前后（2018年6月9日和10月17日）的正射影像数据和数字表面模型,基于2期正射影像提取冰川表面特征点并实施追踪以获得三维位移场,在此基础上初步探明贡巴冰川冰舌段表面位移速率最大为7.51 cm/d,垂向消融速率超过11 cm/d。本文相关研究数据和结果可为冰川及复杂地形山区地质灾害的监测提供参考。 相似文献
12.
Bojan Šavrič Bernhard Jenny 《International journal of geographical information science》2014,28(12):2373-2389
The recently introduced adaptive composite map projection technique changes the projection to the geographic area shown on a map. It is meant as a replacement for the commonly used web Mercator projection, which grossly distorts areas when representing the entire world. The original equal-area version of the adaptive composite map projection technique uses the Lambert azimuthal projection for regional maps and three alternative projections for world maps. Adaptive composite map projections can include a variety of other equal-area projections when the transformation between the Lambert azimuthal and the world projections uses Wagner’s method. To select the most suitable pseudocylindrical projection, the distortion characteristics of a pseudocylindrical projection family are analyzed, and a user study among experts in the area of map projections is carried out. Based on the results of the distortion analysis and the user study, a new pseudocylindrical projection is recommended for extending adaptive composite map projections. The new projection is equal-area throughout the transformation to the Lambert azimuthal projection and has better distortion characteristics then small-scale projections currently included in the adaptive composite map projection technique. 相似文献
13.
3D seismic technology: the geological 'Hubble' 总被引：3，自引：0，他引：3
The proliferation of three‐dimensional (3D) seismic technology is one of the most exciting developments in the Earth Sciences over the past century. 3D reflection seismic data provide interpreters with the ability to map structures and stratigraphic features in 3D detail to a resolution of a few tens of metres over thousands of square kilometres. It is a geological ‘Hubble’, whose resolving power has already yielded some fascinating (and surprising) insights and will continue to provide a major stimulus for research into geological processes and products for many decades to come. Academic and other research institutions have a major role to play in the use of this data by exploiting the enormous volume of geological information contained in 3D seismic surveys. This paper reviews some of the recent advances in basin analysis made using the medium of 3D seismic data, focusing on the fields of structural and sedimentary geology, fluid–rock interactions and igneous geology. It is noted that the increased resolution of the 3D seismic method provided the essential catalyst necessary to stimulate novel observations and discover new geological structures such as mud diapir feeders, km‐long gas blow‐out pipes, giant pockmarks and sandstone intrusions, and to capture the spatial variability of diagenetic fronts. The UKs first impact crater was also discovered using 3D seismic data. The potential for future developments in this field of geophysical interpretation is considerable, and we anticipate that new discoveries will be made in many years to come. 相似文献
14.
支持地图自适应可视化的用户模型设计及试验研究 总被引：3，自引：0，他引：3
对网络电子地图的自适应可视化机制进行了研究,建立了自适应地图可视化系统的自适应用户模型、自适应的数据组织和自适应结构.试验系统主要根据"用图目的"对用户进行划分,建立用户模型;利用地图瓦片技术和背景与热点集成技术,实现了地图瓦片的自适应数据组织以及用户模型支持下的地图自适应可视化等基本功能. 相似文献
15.
N. J. Lim S. A. Brandt S. Seipel 《International journal of geographical information science》2016,30(2):240-262
This study evaluates how users incorporate visualisation of flood uncertainty information in decision-making. An experiment was conducted where participants were given the task to decide building locations, taking into account homeowners’ preferences as well as dilemmas imposed by flood risks at the site. Two general types of visualisations for presenting uncertainties from ensemble modelling were evaluated: (1) uncertainty maps, which used aggregated ensemble results; and (2) performance bars showing all individual simulation outputs from the ensemble. Both were supplemented with either two-dimensional (2D) or three-dimensional (3D) contextual information, to give an overview of the area.
The results showed that the type of uncertainty visualisation was highly influential on users’ decisions, whereas the representation of the contextual information (2D or 3D) was not. Visualisation with performance bars was more intuitive and effective for the task performed than the uncertainty map. It clearly affected users’ decisions in avoiding certain-to-be-flooded areas. Patterns to which the distances were decided from the homeowners’ preferred positions and the uncertainties were similar, when the 2D and 3D map models were used side by side with the uncertainty map. On the other hand, contextual information affected the time to solve the task. With the 3D map, it took the participants longer time to decide the locations, compared with the other combinations using the 2D model.
Designing the visualisation so as to provide more detailed information made respondents avoid dangerous decisions. This has also led to less variation in their overall responses. 相似文献
16.
2008年以来地图学眼动与视觉认知研究新进展 总被引：7，自引：0，他引：7
地图是人类日常生活中不可或缺的工具。地图认知作为研究人对地图的感知、学习、记忆、推理和决策的科学,一直以来是地图学基础理论的重要内容。作为地图认知研究的核心,近年来地图视觉认知在相关学科（如心理学、认知科学和计算机视觉）和新的研究手段（如眼动跟踪、脑电和核磁）的促进下取得了一系列新的研究成果。尤其是眼动跟踪方法作为地图视觉认知研究的重要手段之一,越来越受到研究者的关注,为地图视觉认知研究的定量化、实用化提供了有力支撑。本文系统地梳理了2008年以来眼动跟踪方法在地图视觉认知研究中取得的新进展,并将其归纳为6个发展趋势,分别包括：① 刺激材料：从静态地图到动态交互地图;② 研究范围：从地图认知到地图空间认知;③ 实验环境：从实验室环境到真实环境;④ 地图维度：从二维地图到三维地图;⑤ 个体差异：从单一维度到多维度;⑥ 研究目的：从规律探究到实践应用。本文最后总结了未来研究面临的挑战、难点和可能的解决方法,期望能在地图视觉认知研究中起到抛砖引玉的作用。 相似文献
17.
Jantien Stoter Henk de Kluijver Vinaykumar Kurakula 《International journal of geographical information science》2013,27(8):907-924
Noise mapping is the process of determining and visualizing noise impact on the environment in order to support environmental policies. Currently most noise impact studies are based on a 2D approach. The 3D output of noise simulation software is processed and visualized in 2D and combined with 2D topographical and other data, such as population distribution, to quantify the effects. The research described in this paper aims at improving visualization and assessment of noise impact on the environment by generating a 3D noise map in cases where 3D effects are relevant. Based on the specific demand, an approach is presented to generate a 3D noise map as a basis for noise impact studies. The proposed concept is proofed by applying it to a sample noise impact study. From experiences with the sample, it can be concluded that the 3D noise map offers significant insight in situations where 3D noise effects are relevant, i.e. in urban areas. Here, current 2D noise maps have limitations. In addition, more accurate assessment of noise impact is possible in particular when different floors of a building close to the noise source and/or behind noise barriers are considered. This paper also elaborates on accuracy aspects in all phases of noise modelling, including a presentation of initial experiments of 3D noise interpolation. 相似文献
18.
Nicholas D. Arnold Denis White 《International journal of geographical information science》2017,31(12):2524-2542
Dot mapping is a traditional method for visualizing quantitative data, but current automated dot mapping techniques are limited. The most common automated method places dots pseudo-randomly within enumeration areas, which can result in overlapping dots and very dense dot clusters for areas with large values. These issues affect users’ ability to estimate values. Graduated dot maps use dots with different sizes that represent different values. With graduated dot maps the number of dots on a map is smaller, reducing the likelihood of overlapping dots. This research introduces an automated method of generating graduated dot maps that arranges dots with blue-noise patterns to avoid overlap and uses clustering algorithms to replace densely packed dots with those of larger sizes. A user study comparing graduated dot maps, pseudo-random dot maps, blue-noise dot maps and proportional circle maps with almost 300 participants was conducted. Results indicate that map users can more accurately extract values from graduated dot maps than from the other map types. This is likely due to the smaller number of dots per enumeration area in graduated dot maps. Map users also appear to prefer graduated dot maps over other map types. 相似文献
19.
John J. Bartholdi III Paul Goldsman 《International journal of geographical information science》2013,27(6):489-522
We describe how to create a continuous global index of the surface of the Earth. The index is based on a hierarchical subdivision of the surface into triangular regions in which each region is assigned a numerical label according to a spacefilling curve. Sequential labels are assigned to adjacent regions, so labels can be sorted to create a continuous one-dimensional index. Benefits of continuity include the implicit preservation of adjacency information, and the ability to vary resolution at different locations. Previously suggested schemes based on similar models produce indices that are discontinuous. Unfortunately, discontinuities degrade the usefulness of an index, as we show by comparing continuous and discontinuous schemes based on performance criteria such as the ability to preserve spatial adjacency. The best index appears to be the continuous one based on the Sierpinski spacefilling curve. 相似文献
20.
王琪 《地理与地理信息科学》2007,23(2):39-42
网络环境下进行二维电子地图与三维虚拟场景集成,关键问题之一是数据快速、有效地传输与表达。为了解决网络电子地图与三维虚拟场景集成过程中数据快速传输问题,该文讨论了空间数据多级存储、网络数据流压缩、矢栅数据有机结合、纹理模型及原型模型库等网络传输瓶颈解决方案和模型数据简化方法,为后续网络电子地图和三维虚拟场景集成系统的开发奠定基础。 相似文献