共查询到20条相似文献,搜索用时 31 毫秒
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室内地标在室内位置信息服务(location based service,LBS)中发挥着重要作用。针对室外地标提取方法不能完全适用于更为复杂的室内环境的问题,提出了一种显著度定量评价模型用于在室内环境中提取地标。以大型商场的室内环境为研究对象,从视觉、认知、空间3个方面分析影响室内兴趣点(point of interest,POI)显著性的主要因素,并用这些因素构建了室内POI整体显著度评价模型。选择武汉市群光购物中心室内的POI数据进行显著度计算,依据显著度的差异性提取了多层地标,反映不同粒度的室内区域空间知识。提取的多层地标可以作为室内智能导航系统中的重要标识,为在复杂的大型商场内实现快速寻路、多粒度路径导引提供关键线索。 相似文献
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Saliency detection is an effective approach to extract regions of interest (ROIs) for remote sensing images. However, existing saliency detection models mainly focus on ROI extraction from a single image and usually are not able to produce satisfactory results because of complex background interference in remote sensing images. The employment of mutual information in a set of remote sensing images can provide an effective solution to this issue. In this paper, we propose a novel saliency detection model for multiple remote sensing images to simultaneously extract ROIs and identify images without ROIs. First, common salient feature analysis based on synthesized feature clustering and global contrast is implemented to exploit global correspondence in the synthesis feature domain, thereby highlighting preliminary ROIs against background interference and assigning lower saliency values to images without ROIs. Then, we design an exclusion criterion based on saliency value judgment to remove images without ROIs, and the remaining saliency maps are refined by an enhancement strategy. Finally, the enhanced maps serve as a feedback to yield a homogenous synthesized feature space in which integral ROIs with subtle borders are extracted by the reused cluster-based saliency calculation. Experiments reveal that our model outperforms seven state-of-the-art models by achieving the best ROC curve (AUC = 0.945) and maximal F-measure at 0.729. 相似文献
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《制图学和地理信息科学》2013,40(4):261-278
The purpose of this research was to empirically assess perceptual groupings of various combinations of symbol dimensions (e.g., graphic variables) used in designing bivariate map symbols. Perceptual grouping ability was assessed using the theory of selective attention, a construct first proposed in psychological research. Selective attention theory contends that one's ability to analyze a symbol's dimensions—such as color or size—is affected by other dimensions present in the same symbol. Symbol dimensions are described as either separable (capable of being attended to independently of other dimensions), integral (cannot be processed without interference from other dimensions), or configural (i.e., show characteristics of both integrality and separability, which may also form new, emergent properties). Without empirical evidence describing such interactions for various combinations of symbol dimensions, cartographers cannot truly evaluate the functionality of the symbols they use on maps. The symbol dimensions or graphic combinations chosen for this study were selected to incorporate a wide range of traditional cartographic symbolization, including line and lettering symbolization, areal shading, dot patterns, and point symbols. Combinations were examined in an abstract setting using a speeded classification task, which is the traditional means of studying selective attention. Subject reaction times provided an assessment of the levels of integrality, separability, and configurality. Results suggest that most symbol dimension combinations are either separable or exhibit evidence of asymmetrical dimensional interactions. Findings from this study will be integrated into subsequent experiments, the results of which will assist cartographers in the design of complex map symbols. 相似文献
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《制图学和地理信息科学》2013,40(4):373-383
Coordinated view geovisualizations allow users to interactively pick and attend to data observations across multiple views. This is frequently supported by the transient application of a visual effect to an observation during a mouse selection or rollover. This technique, known as highlighting, is typically implemented using a dedicated bright and saturated color to outline observations. In this paper we present a range of possibilities for alternative approaches to color highlighting, beginning with examples from the range of available visual variables and moving beyond those options to other, non-visual variable methods such as the use of lines to connect highlighted observations. We also describe design criteria for highlighting methods that can be used to predict and test the suitability of different approaches, and apply those criteria to our set of proposed methods to identify potential good candidates for implementation in future systems. Next, we present a set of highlighting types that define basic ways in which highlighting methods can be combined, modified, and driven directly by data values. We conclude by outlining several broad research challenges for future work on the development and evaluation of highlighting methods in geographic visualization. 相似文献
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在熵理论和地图分级评价模型的基础上,提出了基于熵的彩色晕渲图设色方案辅助设计方法,并进行了晕渲制图实验.从客观信息量测定和主观评价结果的分析表明,本文方法制作的晕渲图色彩过渡自然,地形区分明显,层次清晰,能更好地表达地貌形态. 相似文献
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《制图学和地理信息科学》2013,40(2):98-106
The quality of dynamic map symbols plays an important role in the representation of spatial-temporal changes. This paper reports an investigation into the quality of dynamic symbols. To assess the quality of such symbols, a set of traffic flow data is used for the production of different kinds of dynamic maps, with focus on four variables, i.e. size, color, frame rate and display format. Two quantitative measures are used for analysis, i.e. deviation and response time. A set of traffic data is used for the production of dynamic maps for evaluation. The experimental results show that the size is more efficient and more effective than color for dynamic maps with the same frame rate and display format. The most efficient and effective color class number is 10 on the large format display such as 1024 × 768 pixels. And the most efficient and effective size class number is 15 on large format display such as 1024 × 768 pixels. The effective frame rate for dynamic map animation is smaller than that of the general animation on the Internet or Quick Time and AVI format video. The most efficient and most effective frame rate is 3 frames per second in the color expression and 6 frames per second in the size expression. In sum, the effective and efficient value of color, size and frame rate on large format display is less than the value on the small format display. These results suggest the frame rate should be reduced on the small format display. It is hoped that the results from this study will be of help in the design of effective and efficient dynamic map symbols for geographical information visualization. 相似文献
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土地利用现状图扫描符号的自动提取能节省人力财力物力。本文采用地图代数和人工神经网络的方法进行扫描现状图符号的自动提取和识别。首先根据图例建立用于特征匹配的符号模板库,然后使用加壳变换和蜕皮变换进行点状符号和线状符号的分离,并使用Canny算子平滑符号,再通过人工神经网络的训练进行色彩聚类而实现符号分割。定义多重相似度,实现符号的预分类识别,在此基础上计算加权距离再次识别。最后采用加壳变换连接断点并提取骨架线对这些断线进行连接,形成完整的线状符号。实验表明,本方法的正确率达到90%以上。 相似文献
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Richard A. Snay 《Journal of Geodesy》1986,60(1):37-50
Strategies applicable to the design ofGPS surveys involving deployment of either three or four compatible receivers are presented. During aGPS observing session, the receivers operate simultaneously, producing three-dimensional cartesian coordinate differences for
the lines interconnecting the receivers. Different strategies provide the network designer with several options for planning
the survey. The designer may opt for a survey in which each mark is occupied three times, that is, during three separate observing
sessions, or he may elect a more economical survey in which each mark is occupied only twice. The designer may also choose
between two fundamentally different network geometries (a loop geometry or an areal geometry) to design a survey compatible
with the spatial distribution of network marks. The strategies can be extended to other geometries. The strategies produce
efficient networks in that no two marks are jointly occupied for more than one observing session. This feature produces the
maximum number of distinct, directly observed lines for the given number of receivers and observing sessions. The strategies
also favor observations over those lines connecting marks near one another. This feature helps survey logistics by reducing
travel time between observing sessions. 相似文献
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《The Cartographic journal》2013,50(3):230-241
Map data at smaller scales than their source can result in spatial conflict, whereby map symbols become too close, or overlaid. Server map generalisation operators may be applied to solve this problem, including displacement. In this paper, we show how an optimisation algorithm, the snake algorithm, was used to displace multiple objects in order to resolve spatial conflicts and maintain important spatial relationships between objects during displacement. Two principles based on the snake algorithm are proposed in this paper. First, the truss structure mirroring spatial proximity relationships between buildings and between building and road is formed based on the weighted proximity graph derived from constrained Delaunay triangulations (CDT) in each map partition. In the weighted proximity graph, each connecting line is determined as a snake and as an element unit to assemble the global stiffness matrix in snake algorithm. Second, a buffer method that calculates force between a building and a road (or other linear features) or between pair of buildings is adopted in the snake algorithm. This avoids the imbalance phenomenon caused by different force calculation methods during the displacement. The feasibility of the approach is demonstrated in obtaining real geographic data. Finally, the results are cartographically usable and in particular, the spatial relationships between objects are preserved. 相似文献
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应急指挥信息系统中三维模型快速构建方法研究 总被引:1,自引:1,他引:0
本文结合处置公共突发事件应急指挥信息系统对三维模型快速构建的实际需求,基于标准的三维城市模型表达原则与分类,针对不同的数据源,提出了基于统一规范、基于标准模型符号库和基于非仿真功能写景等三维模型快速构建方法。这几种方法方便、快捷、自动化程度高,为处突指挥战法研究和首长更直观更形象地掌握事发现场情况提供了技术支撑。 相似文献
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联合显著性和多层卷积神经网络的高分影像场景分类 总被引:3,自引:2,他引:1
高分辨率遥感影像中的场景信息,对于影像解译和现实世界的理解具有重要意义。传统的场景分类方法多利用中、低层人工特征,但是高分辨率遥感影像的信息丰富,场景构成复杂,需要高层次的特征来表达。本文提出了一种联合显著性和多层卷积神经网络的方法,首先利用显著性采样获取包含影像主要信息的有意义的块,将这些块作为样本集输入卷积神经网络中进行训练,获得不同层次的特征表达,最后联合多层特征利用支持向量机进行分类。两组高分影像场景数据UC Merced 21类和Wuhan 7类试验表明,显著性采样能够有效地获取主要目标,减弱其他无关目标的影响,降低数据冗余;卷积神经网络能够自动学习高层次的特征,相比已有方法,本文方法能够有效提高分类精度。 相似文献
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AbstractIt is difficult to automatically recognize complex ground objects, and massive data images with the super-high ground resolution in images captured by unmanned aerial vehicles (UAVs). In order to directly identify the salient man-made ground objects from the UAV remote sensing (RS) image, a saliency detection method based on saliency potential energy (SPE) is proposed. With a detection, filtration and backtracking strategy, the texture, shape and colour of the UAV RS image are comprehensively and numerally analysed by the SPE to detect the salient man-made objects. Both qualitative and quantitative evaluations have indicated that, compared to the state-of-art saliency detection methods, our method could achieve better performance with better accuracy and less errors, which prove that our method has great application potential in UAV RS image understanding. 相似文献
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The displacement operator is an important and still a hot topic in map generalization. In the generalization product, symbols
must be unambiguous and easily perceived and readily understood, which makes space competition among features an important
obstacle in the process of map objects displacement. Space conflict between objects, through propagation process, may be spread
and more objects may drift into it. In order to maintain symbols equilibrium and spatial relationship between objects, some
unimportant symbols or parts of symbols should be distorted under constraints according to visual graphic resolution thresholds
to figure out space competition among map features. Three constraints including position, legibility and characteristics are
important for the maintenance of symbols equilibrium and spatial relationship, which are discussed in this paper. The skeleton
is introduced to represent area objects figure characteristic, in which an area object can be separated to parts hierarchically
according to their importance in the construction. Then, the finite element method is applied to the map objects’ displacement
and distortion, in which a strategy for the parameters of finite element method is discussed.
Supported by the National Science Foundation of China (No.40401050), the Leading Academic Discipline Project of Shanghai Educational
Committee (No.J50104), the Science Foundation of Shanghai Education Department (07ZZ09). 相似文献
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Jérémie Ory Sidonie Christophe Sara Irina Fabrikant Benedicte Bucher 《The Cartographic journal》2013,50(2):193-203
The process of reading a topographic map requires users to recognize and learn the cartographic symbols of the key (or legend) while interpreting the territory as depicted on the map at a given level of abstraction (the form and nature of features, their saliency and relationships). We present the results of an empirical user study that aims to identify and assess the main graphical characteristics that are used by map users to recognize the design principles which constitute the topographic mapping style adopted by IGN (Institut National de l'Information Géographique et Forestière), France. Our results suggest that 91% of the participants were able to recognize an IGN-France topographic map amongst other topographic map products. We also determine which graphical characteristics play a role in the recognition of this cartographic style, either by visual memory or by visual perception, and identify the representation of relief, including contour lines and shaded relief, as one of the major graphical characteristics of the topographic mapping style of IGN-France. Moreover, the participants of our study considered the representation of touristic POI (points of interest), toponymy, typography, the main roads network, the individual buildings and the forests, to be essential for stylistic recognition. 相似文献