共查询到20条相似文献，搜索用时 15 毫秒
1.
Howard Veregin 《International journal of geographical information science》2013,27(2):113-130
This study examines the effects of line simplification on the positional accuracy of linear features. The goal is to quantify the relation between the level of simplification and the degree of positional error, so that users can choose appropriate levels of simplification that will yield results meeting specific accuracy criteria. The study focuses on the Douglas-Peucker line simplification algorithm and examines both natural and anthropogenic features (streams and roads) derived from United States Geological Survey Digital Line Graphs. Results show that error can be modelled at an aggregate level using cumulative frequency curves and their confidence limits. This makes it possible to identify the level of simplification that eliminates the largest number of vertices while still attaining a specific positional accuracy standard. A simple implementation strategy is described in which an optimal level of simplification is identified and simplification is applied selectively for different lines. The study shows that management of simplification induced error is possible using simple tools well within the reach of GIS users. 相似文献
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A new method based on orthogonal least square (OLS) of multiquadric algorithm (MOLS) is proposed for digital elevation model (DEM) generalization by the retrieval of critical points from a grid-based DEM to construct a triangulated irregular network surface. The focus is on the method for accurately obtaining the critical points, which maximally retain the important terrain feature lines. The grid-based DEM to be generalized is first approximated in terms of multiquadric method, and then the significances of the grids are assessed based on OLS method with the merit that each selected grid point gives the maximal increment to the explained variance of the desired output. We used six study sites with different terrain complexities to comparatively analyze the generalization accuracies of MOLS and the classical methods including very important method and point-additive method (Latticetin) under different numbers of retrieved significant points. The results indicate that MOLS averagely performs better than the classical methods for the original DEM generalization in terms of root mean square error. The analytical results also show that MOLS has the better ability in maintaining the feature lines inherent in the original DEM than the classical methods in terms of streamline matching rate. The perfect performance of the newly proposed method can be attributed to the high accuracy of multiquadric method for surface approximation and the effectiveness of OLS for point significance assessment. 相似文献
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地图综合是当前国际GIS和制图学领域的一个难题。化简是地图综合的一个基本操作算子,线要素是地图综合操作的主要对象,该文主要研究地图线要素的化简问题。首先,从算法的适用范围、阈值设置等方面分析了现有算法的优点,重点阐述了一种常用的弧比弦算法,并指出了其在化简过程中存在的不足。然后,基于地图曲线的空间认知特征,提出了一种改进弧比弦算法。该算法能够更好地保持曲线的特征点和曲线的几何形态,避免阈值的设置问题。在算法评价上,采用3种定量评价指标,即:偏移平均值、偏移量中值和面积变形值,对改进的弧比弦算法与现有经典算法进行了比较分析。最后,通过算例分析验证了该算法的可行性、有效性和健壮性。 相似文献
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Zhilin Li 《International journal of geographical information science》2013,27(11):1631-1647
This article deals with the graphic simplification of a network by schematization. A new method employing a stroke-based and progressive strategy is proposed to generate schematic network maps. This method treats a stroke (which is a long line with segments concatenated together) as a basic unit for the implementation. The procedure is as follows: (a) strokes are formed from line segments, (b) the strokes are re-orientated along grid lines and/or diagonals, and (c) two endpoints and all intersection points on (sub-)strokes are projected onto re-oriented straight lines, and (d) spatial inconsistency is detected and resolved. A methodology for each of these steps is described. This new method has been tested with a set of real-life road network data and evaluated by fractal analysis and empirical study. Experimental results show that this new method is more effective than segment-based methods and is able to produce graphics with great simplicity and clarity. Based on the results obtained, the stroke-based schematization with four primary directions is recommended. 相似文献
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一种基于面积平衡约束的图斑化简算法 总被引：1，自引：0，他引：1
保持综合前后各地类土地面积平衡是土地利用数据综合的基本原则.地类图斑是面积统计的最小单元,用常规的线化简算法不但难以保证图斑的地理特性,而且会给面积统计带来不确定性.该文提出一种能够使图斑化简前后面积保持绝对平衡的化简算法,该算法给出了求取图斑群和岛图斑的地理特征点、几何特征点的相关方法,对被特征点分割的综合子弧段运用直线面积平衡和参数曲线面积平衡两种求取平衡线的方式进行化简,基本原理是综合前后弧段切割它们自身的包络矩形面积比相等,且综合后的弧段须落入综合前子弧段的误差缓冲区内.实验表明,该算法不但能保持图斑的形态特征,而且能保持图斑化简前后面积绝对相等. 相似文献
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基于逆向加权Voronoi图的方法,采用角度、线宽、线长和方向四参数对面状地理景观进行特征化研究。实例表明,该方法既具备在保持曲线弯曲特征转折点精确性方面的优点,还在曲线化简时重点顾及了目标的形态维护,并在不损耗面状地理景观的方向、凹凸性及数量等关键信息的基础上,明显减少了数据存储量,还可实现面状目标的跨时段、跨地区比较,是一种记录、描述和可视化比较研究面状地理景观时空演化特征的有效方法,可实现特征信息保留与结果简化间的平衡。 相似文献
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A quantitative procedure for analyzing and comparing distortion in mental maps is presented. Using a microcomputer and digitizer, and by developing a distortion index, comparisons are made by direct analysis of mental maps. A case study of the mental maps of Israel of high school and university students showed a tendency to generalize shape to simple geometric forms, with foreshortening of north-south lines and exaggeration of east-west distances. 相似文献
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土地利用现状数据缩编的质量评价方法 总被引：2，自引：0，他引：2
土地利用现状数据缩编是为了满足土地管理工作中不同级别的行政区需求对不同尺度的土地利用数据进行的简化、分类、归纳、符号化等工作,缩编应能使不同尺度的数据表达的土地利用信息保持最大程度的一致,缩编的质量直接影响缩编结果可用性.本文提出了缩编结构相似度指数、缩编布局相似度指数、缩编罔斑适宜度指数辅助传统的相关性统计指标,用来... 相似文献
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C. B. Jones D. B. Kidner L. Q. Luo G. Ll. Bundy J. M. Ware 《International journal of geographical information science》2013,27(8):901-920
Abstract Growth in the available quantities of digital geographical data has led to major problems in maintaining and integrating data from multiple sources, required by users at differing levels of generalization. Existing GIS and associated database management systems provide few facilities specifically intended for handling spatial data at multiple scales and require time consuming manual intervention to control update and retain consistency between representations. In this paper the GEODYSSEY conceptual design for a multi-scale, multiple representation spatial database is presented and the results of experimental implementation of several aspects of the design are described. Object-oriented, deductive and procedural programming techniques have been applied in several contexts: automated update software, using probabilistic reasoning; deductive query processing using explicit stored semantic and spatial relations combined with geometric data; multiresolution spatial data access methods combining poini, line, area and surface geometry; and triangulation-based generalization software that detects and resolves topological inconsistency. 相似文献
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Peng Ti 《International journal of geographical information science》2014,28(3):521-540
Nowadays, the design of the London Tube map (as a kind of schematic map) has been popularly adopted for transport network maps worldwide because of its great clarity of representation. In such types of map, the shape of the network is simplified and the topology between lines is preserved while the congested areas are enlarged to a desirable scale. Efforts have also been made to automate the production of such maps. However, to our best knowledge, no existing methods have explicitly taken into consideration the automated enlargement of congested areas. As such an enlargement is vital to the improvement of clarity, this paper proposes a new automated method to generate schematic network maps, consisting of (a) automated detection of congested areas, (b) automated enlargement of congested areas to a desirable scale and (c) automated generation of the schematic representation of the deformed network maps using a stroke-based approach. The new method has been tested with two real-life network data sets, i.e. the London Tube and Hong Kong metro data sets, and evaluated by fractal analysis and experimental studies. The results of the evaluation indicate that the new method is able to automatically generate the schematic maps with improved clarity and aesthetics. 相似文献
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和田河流域灌(草)丛沙堆的形态特征与发育过程 总被引：5，自引：0，他引：5
灌 (草)丛沙堆形态是由区域植物、风力和沙源相互作用塑造的一种动力平衡形态。本文在对新疆和田河流域灌 (草)丛沙堆野外考察、形态测量和统计分析的基础上,探讨了该区灌 (草)丛沙堆的形态变化规律和不同发育阶段的特征,结果表明:各种灌 (草)丛沙堆的长度、宽度与高度之间存在着较好的相关性,但不同种类灌 (草)丛沙堆以及同一类型沙堆在不同发育阶段的形态特征存在一定差异;基于沙堆形态特征的数学模型分析,并结合区域生态环境和风沙环境特点,可把灌 (草)丛沙堆发育划分为各形态指标协同变化的增长阶段,以植物动力影响为主、长宽尺度均衡发展、坡度较大的稳定阶段,以及沙堆长度相对缩短、各形态指标关系趋于复杂的风蚀衰退阶段。 相似文献
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针对ArcSDE多图素图层刷新渲染速度较慢现状,提出了图层数据的预处理与优化技术,涉及的关键环节包括:合并要素类、预生成注记图层、图层抽稀和预统一图层坐标投影等策略,并在各种比例尺下对优化策略与系统响应时间之间关系进行了测试与验证.最后结合某飞行体监控系统项目开发实践,证明了该技术在加快ArcSDE多图素图层刷新渲染速度上具有一定的可行性和实用性. 相似文献
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Loess terrain segmentation from digital elevation models based on the region growth method 总被引：1，自引：0，他引：1
Regional automatic segmentation – automatic terrain segmentation according to terrain features – is significant for modern geographical analysis. We propose a new approach of terrain region segmentation based on the region growth method. This method features actual runoff nodes as seed points. The corresponding growth threshold is defined based on statistical analysis of quantitative indexes of topographic features. Terrain segmentation of some regions is completed using the growth threshold. The corresponding edge boundaries of different terrain regions are extracted by image processing. Thus, the automatic segmentation of the terrain region is realized by the edge boundary. The application of the method to a typical Chinese loess landform area and automatic segmentation of three types of terrain regions – gully interfluve land, gully slope land, and gully groove land – are achieved by analyzing characteristics of the curvature structure of surface profiles. Segmentation results, compared with results of visual interpretation from a high-precision digital orthophoto map, show an average accuracy of segmentation of 93.51%. Topographic factor features of segmentation results are statistically analyzed. This study presents an effective and practical approach for segmenting terrain regions. This approach may be incorporated into the theory and method system of digital terrain analysis. 相似文献
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A typical requirement in digital society is the rapid distribution and effective application of digital products. Geographical data bases are far more complex than other ones in that both attribute and spatial data have to be stored and handled under the same framework. On the other hand, the number of end users of digital cartographic data is explosively increasing, ranging from professional map makers to vehicle drivers and individual tourists. Thus arises a question: how can a data supplier give the “best” service to each user? In nature it involves such difficult problems as cartographic generalization and map simplification. In this paper, the author argues that the visual knowledge or perception experience can be effectively exploited and used to guide the process of data simplification. We have developed a prototype system with a subset of the vector road database covering Munich city.
相似文献18.
街网约束下的城市居民地自动综合算法 总被引：2，自引：0，他引：2
街网约束下的城市居民地自动综合是地图综合中的一个难点,该文从居民地多边形化简、居民地合并等方面讨论街网约束下城市居民地自动综合算法,并研究综合操作后居民地与街道冲突的解决方法.由此实现的城市居民地自动综合功能用于实验数据中,对多边形形态的化简、合并及街道形态的保持都较无约束条件下的居民地综合更合理. 相似文献
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Luke Bermingham 《International journal of geographical information science》2017,31(6):1128-1153
We present an extensible, generic, spatio-temporal trajectory simplification framework that modularises trajectory simplification into the stages of normalising, ranking, and reduction. We combine a range of ranking strategies and scoring heuristics – some from the literature and some new – into our framework modules and create a variety of spatio-temporal trajectory simplification methods. These trajectory simplification methods are experimented upon using real world and synthetic datasets, measuring running time, geometric displacement, and region-of-interest visitation. The results indicate that our proposed framework creates a number of efficient and effective spatio-temporal trajectory simplification methods. 相似文献
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Cause-Effect Analysis in Assessment of Mineral Resources 总被引：1，自引：0，他引：1
Cause-effect analyses is a deterministic methodology intended for processing qualitative (e.g. texts, conventional maps) and mixed, qualitative and quantitative, data. The main idea, employed in cause-effect analysis, is the plurality and interaction of causes. This idea is described by mathematical logic formulae that can be converted into a single Boolean equation. The latter represents a mathematical model of a general shape of cause-effect relations for the study problem. In particular, such a model can express relations between some property of the mineralization and features of other geological phenomena. By processing data, logical dependencies satisfying to the theoretical model are determined in a data file. These dependences, expressed by Boolean function formulae, describe cause-effect relations for a case study, and they are used for predicting. Software realizing the cause-effect analysis is an expert system with artificial intelligence capabilities. There are two methods of using the cause-effect analysis in assessment of mineral resources. The first method consists in detecting the regularity in locations of known mineral deposits and occurrences with the following using the regularity formula for generation of predictive maps. The second method is the evaluation of individual mineral occurrences by obtained Boolean formulae expressing cause-effect relations between deposit sizes and geological environment of deposits. Both methods are illustrated by case studies of predicting gold-bearing deposits of Middle Asia in the former USSR. 相似文献