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1.
Multi-representation databases (MRDB) are used in several Geographical Information System applications for different purposes. MRDB are mainly obtained through model and cartographic generalizations. The model generalization is essentially achieved with the selection/elimination process in which a decision must be made to include or exclude the object at the target level. In this study, support vector machines (SVM) was, for the first time, used for the selection/elimination process in stream network generalization. Within this context, the attributes to be used as input data in the SVM method were determined and weighted according to the associations determined in a chi-squared independence test. 1:100,000-scale (medium resolution) stream networks were derived from two 1:24,000-scale (high resolution) stream networks with different patterns in the United States Geological Survey National Hydrography Data-sets. The derived stream networks were quite similar to the 1:100,000-scale original stream networks in both qualitative and visual aspects. 相似文献
2.
提出了一种运用自组织映射识别网格模式的方法。首先,计算街道网中网眼的参数,这些参数是质心、面积、矩形度、延展度、是否含有平行边、边数、一阶邻居数和矩形度平均值;然后,将网眼作为自组织映射的向量进行训练,利用U-matrix可视化方法挖掘聚类得出结果。实验结果表明,该方法能有效地从不规则街道网中识别出网格模式。 相似文献
3.
本文研究基于SOM(Self-Organizing Feature Map)神经网络学习模型的高分辨率遥感影像道路网自动提取算法。首先利用数学形态学提取遥感图像道路的初始道路区域信息,自动对原始图像进行分区并确定神经元初始权值,用SOM网络学习模型对神经元进行训练学习,经迭代获取道路网中心点位置,最后运用"中心点四邻域跟踪判别法"跟踪连接形成道路中心线。实验表明,该方法在高分辨率遥感影像道路网的提取上有较好的效果,特别在主干道路网的提取上效果更佳,对噪声干扰具有良好的鲁棒性。 相似文献
4.
The drainage network of a sixth-order tropical river basin, viz. Ithikkara river basin, was extracted from different sources such as Survey of India topographic maps (1: 50,000; TOPO) and digital elevation data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) (30 m) and Shuttle Radar Topography Mapping Mission (SRTM) (90 m). Basin morphometric attributes were estimated to evaluate the accuracy of the digital elevation model (DEM)-derived drainage networks for hydrologic applications as well as terrain characterization. The stream networks derived from ASTER and SRTM DEMs show significant agreement (with slight overestimation of lower order streams) with that of TOPO. The study suggests that SRTM (despite the coarser spatial resolution) provides better results, in drainage delineation and basin morphometry, compared to ASTER. Further, the variability of basin morphometry among the data sources might be attributed to spatial variation of elevation, raster grid size and vertical accuracy of the DEMs as well as incapability of the surface hydrologic analysis functions in the GIS platform. 相似文献
5.
《The Cartographic journal》2013,50(1):38-51
AbstractAn important problem faced by national mapping agencies is frequent map updates. An ideal solution is only updating the large-scale map with other smaller scale maps undergoing automatic updates. This process may involve a series of operators, among which selective omission has received much attention. This study focuses on selective omission in a road network, and the use of an artificial neural network (i.e. a back propagation neural network, BPNN). The use of another type of artificial neural network (i.e. a self-organizing map, SOM) is investigated as a comparison. The use of both neural networks for selective omission is tested on a real-life road network. The use of a BPNN for practical application road updating is also tested. The results of selective omission are evaluated by overall accuracy. It is found that (1) the use of a BPNN can adaptively determine which and how many roads are to be retained at a specific scale, with an overall accuracy above 80%; (2) it may be hard to determine which and how many roads should be retained at a specific scale using an SOM. Therefore, the BPNN is more effective for selective omission in road updating. 相似文献
6.
B. B. Serapinas 《地理信息系统科学与遥感》2013,50(4):247-255
The author outlines a method for quantitative analysis of the completeness of information presented on maps of varying scale, i.e., for determining, upon reductions in scale of an original map A, what magnitudes of loss in graphic detail will result in derivative maps B, C, D that are of equal relative completeness to the original. Empirical formulae are derived which describe intensities of selection typical of maps devoted to particular topics (stream networks, urban socioeconomic indices, etc.) and graphic methods are described which can be used to determine scale denominators at which specific reductions in the number of features can occur without losses in “completeness” or, conversely, the number of particular kinds of features that can be eliminated on maps (or portions of maps) upon reductions in scale without losses in completeness. Translated from: Vestnik Moskovskogo Universiteta, geografiya, 1985, No. 5, pp. 17–23. 相似文献
7.
《制图学和地理信息科学》2013,40(4):321-344
In this paper I discuss the potential of U.S. Geological Survey Digital Line Graph data for applications to microcomputer-based cartographic and geographic information systems. The DLG-3 data base produced from 1:100,000-scale maps is the principal focus because of its importance in providing the cartographic framework for the 1990 decennial census. Topological relationships inherent in DLG-3 data are reviewed as a basis for discussion of how additional digital cartographic data, including the U.S. Geological Survey Land Use and Land Cover data can be converted to the same DLG-3 data structure. The development and applications of software implemented to manipulate DLG-3 data on a microcomputer are reviewed and illustrated through examples of DLG-3 formatted data. 相似文献
8.
Monitoring biophysical and biochemical vegetation variables in space and time is key to understand the earth system. Operational approaches using remote sensing imagery rely on the inversion of radiative transfer models, which describe the interactions between light and vegetation canopies. The inversion required to estimate vegetation variables is, however, an ill-posed problem because of variable compensation effects that can cause different combinations of soil and canopy variables to yield extremely similar spectral responses. In this contribution, we present a novel approach to visualise the ill-posed problem using self-organizing maps (SOM), which are a type of unsupervised neural network. The approach is demonstrated with simulations for Sentinel-2 data (13 bands) made with the Soil-Leaf-Canopy (SLC) radiative transfer model. A look-up table of 100,000 entries was built by randomly sampling 14 SLC model input variables between their minimum and maximum allowed values while using both a dark and a bright soil. The Sentinel-2 spectral simulations were used to train a SOM of 200 × 125 neurons. The training projected similar spectral signatures onto either the same, or contiguous, neuron(s). Tracing back the inputs that generated each spectral signature, we created a 200 × 125 map for each of the SLC variables. The lack of spatial patterns and the variability in these maps indicate ill-posed situations, where similar spectral signatures correspond to different canopy variables. For Sentinel-2, our results showed that leaf area index, crown cover and leaf chlorophyll, water and brown pigment content are less confused in the inversion than variables with noisier maps like fraction of brown canopy area, leaf dry matter content and the PROSPECT mesophyll parameter. This study supports both educational and on-going research activities on inversion algorithms and might be useful to evaluate the uncertainties of retrieved canopy biophysical and biochemical state variables. 相似文献
9.
A Comparison Between Contour Elevation Data Sources for DEM Creation and Soil Carbon Prediction, Coshocton, Ohio 总被引：1，自引：0，他引：1
A raster and vector GIS was created for the North Appalachian Experimental Watershed (NAEW) from legacy (1960) 1:2,400‐scale contour maps. The intent of the study was to use terrain data for the spatial modeling of soil organic carbon. It was hypothesized that DEMs derived from these data would be more accurate and therefore more useful for terrain‐based soil modeling than those from USGS 1:24,000‐scale contour data. Central tasks for this study were to digitally capture the 1:2,400‐scale maps, convert digital contour data sources to raster DEMs at multiple resolutions, and derive terrain attributes. A flexible approach was adopted, using software outside of mainstream GIS sources where scientifically or practically advantageous. Elevation contours and streamlines were converted to raster DEMs using ANUDEM. DEMs ranging in resolution from 0.5–30 m were tested for accuracy against precision carrier‐phase GPS data. The residual standard deviation was 1.68 meters for the USGS DEM and 0.36 meters for the NAEW DEM. The optimal horizontal resolution for the NAEW DEM was 5 m and for the USGS 10 m. Five and 10 m resolution DEMs from both data sources were tested for carbon prediction. Multiple terrain parameters were derived as proxies for surficial processes. Soil samples (n = 184) were collected on four zero‐order watersheds (conventional tillage, no‐till, hay and pasture). Multiple least squares regressions (m.l.s.) were used to predict mass C (kg m?2, 30 cm depth) from topographic information. Model residuals were not spatially autocorrelated. Statistically significant topographic parameters were attained most consistently from the 5 m NAEW DEM. However, topography was not a strong predictor of carbon for these watersheds, with r2 ranging from 0.23 to 0.58. 相似文献
10.
《地理信息系统科学与遥感》2013,50(4):258-272
Soil survey maps compiled at a variety of scales (1:5,000; 1:100,000; 1:500,000) were incorporated into a GIS and compared in terms of the number of soil classes (and discrete soil units belonging to these classes) that could be identified on the basis of the System of Analysis for Agricultural Planning (SAMPA). Significant differences in the number of soil classes were observed between the detailed (1:5,000) survey and the two others. The semi-detailed (1:100,000) and the recognition (1:500,000) maps did not differ in terms of the number of soil classes depicted, but there were nonetheless differences in soil classification, which has a direct bearing on their utility for land use planning. 相似文献
11.
12.
Lawrence V. Stanislawski Kornelijus Survila Jeffrey Wendel Yan Liu Barbara P. Buttenfield 《制图学和地理信息科学》2018,45(4):319-328
This paper describes a workflow for automating the extraction of elevation-derived stream lines using open source tools with parallel computing support and testing the effectiveness of procedures in various terrain conditions within the conterminous United States. Drainage networks are extracted from the US Geological Survey 1/3 arc-second 3D Elevation Program elevation data having a nominal cell size of 10 m. This research demonstrates the utility of open source tools with parallel computing support for extracting connected drainage network patterns and handling depressions in 30 subbasins distributed across humid, dry, and transitional climate regions and in terrain conditions exhibiting a range of slopes. Special attention is given to low-slope terrain, where network connectivity is preserved by generating synthetic stream channels through lake and waterbody polygons. Conflation analysis compares the extracted streams with a 1:24,000-scale National Hydrography Dataset flowline network and shows that similarities are greatest for second- and higher-order tributaries. 相似文献
13.
This study analyzed the relationship between the spatial resolution and the hard classification effect based on pixel-based image classification, and then discussed how to determine appropriate spatial resolution. Thematic maps of winter wheat derived from 250 m MODIS image, 19.5 m China-Brazil Earth Resources Satellite (CBERS) image, and 2.44 m QuickBird image were used to examine the classification effect as a case study. It indicated that the “Pareto Boundaries” and the “within-class variability” could be used to determine the coarsest and the highest resolution for hard classification, respectively. The methods proposed in this study should be useful to guide how to select appropriate spatial resolution for land cover mapping. 相似文献
14.
Selection of Streets from a Network Using Self-Organizing Maps 总被引：6，自引：0，他引：6
We propose a novel approach to selection of important streets from a network, based on the technique of a self‐organizing map (SOM), an artificial neural network algorithm for data clustering and visualization. Using the SOM training process, the approach derives a set of neurons by considering multiple attributes including topological, geometric and semantic properties of streets. The set of neurons constitutes a SOM, with which each neuron corresponds to a set of streets with similar properties. Our approach creates an exploratory linkage between the SOM and a street network, thus providing a visual tool to cluster streets interactively. The approach is validated with a case study applied to the street network in Munich, Germany. 相似文献
15.
A method for the compilation of 1:3,000,000-scale maps of natural nival-glacial phenomena is proposed for an area of the High Pamir Range in Soviet Central Asia. Such maps depict the distribution, frequency and intensity/magnitude, and potential impacts of such natural hazards as avalanches, mudslides, “dirty snow” avalanches (combined avalanches-mudslides in late spring), icings (naledy), and glacier pulsations, and are used in the planning of construction and the maintenance of roads and other transportation corridors during winter and spring. Hypothetical examples of the use of the maps are provided. Translated from: Materialy glyatsiologicheskikh issledovanly, USSR Geophysical Committee Publication No. 55. Moscow: Mezhduvedomstvenniy geofizicheskiy komitet, 1986, pp. 213–219. 相似文献
16.
Automated Extraction of Natural Drainage Density Patterns for the Conterminous United States through High-Performance Computing 总被引：1，自引：0，他引：1
Lawrence V. Stanislawski Jeff Falgout Barbara P. Buttenfield 《The Cartographic journal》2013,50(2):185-192
Hydrographic networks form an important data foundation for cartographic base mapping and for hydrologic analysis. Drainage density patterns for these networks can be derived to characterize local landscape, bedrock and climate conditions, and further inform hydrological and geomorphological analysis by indicating areas where too few headwater channels are represented. Natural drainage density patterns are not consistently available in existing hydrographical data bases for the United States because compilation and capture criteria historically varied, along with climate, during the period of data collection over the various terrain types throughout the country. This paper demonstrates an automated workflow that is being tested in a high-performance computing environment by the U.S. Geological Survey (USGS) to map natural drainage density patterns at the 1:24,000-scale (24K) for the conterminous United States. Hydrographic network drainage patterns may be extracted from elevation data to guide corrections for existing hydrographic network data. The paper describes three stages in this workflow including data pre-processing, natural channel extraction, and generation of drainage density patterns from extracted channels. The workflow is implemented in parallel fashion by simultaneously executing procedures on multiple subbasin watersheds within the U.S. National Hydrography Dataset (NHD). Pre-processing defines parameters needed for the extraction process. Extraction proceeds in standard fashion: filling sinks, developing flow direction and weighted flow accumulation rasters. Drainage channels with assigned Strahler stream order are extracted within a subbasin and simplified. Drainage density patterns are then estimated with 100-m resolution and subsequently smoothed with a low-pass filter. The extraction process is found to be of better quality in higher slope terrains. Concurrent processing through the high-performance computing environment is shown to facilitate and refine the choice of drainage density extraction parameters and more readily improve extraction procedures than conventional processing. 相似文献
17.
Mohadeseh Amiri Karim Solaimani Mirhassan Miryaghoubzadeh 《Journal of the Indian Society of Remote Sensing》2013,41(4):749-755
Vegetation maps are essential tools for planning and evaluation in nature conservation. To a large extend, management objectives can be defined in terms of vegetation attributes. Vegetation maps are frequently used in conservation planning and evaluation. Nowadays, remote sensing is one of the most important sources of vegetation cover classifications at different scales. In this paper, the usefulness of moderate resolution images for invasive species Cirsium arvense and Stachys byzanthina mapping at local scale is evaluated. A fuzzy classification approach is tested for improved discrimination of invasive species. The study was carried out in Vazroud rangelands located in the Mazandaran province of Iran. In this study among the analysed Z-score for uncertainty map creation is found that 0.9, 1.0 for TM image and 1.1 for IRS image in normalized are the best based on known attributes of the study area. 相似文献
18.
根据影像中地物光谱曲线的小波特征点确定地物识别的合适光谱分辨率,通过融合原先若干窄波段生成具有适合地物识别光谱分辨率的宽波段数据,达到降维高光谱数据的目的。文中对hyperion影像进行坏线和Smile效应去除,经过FLAASH大气校正,得到155个波段。对提取的八类地物的样本平均光谱进行DB4小波分解,计算小波细节系数方差;以小波细节系数信息熵作为特征点,得出不可渗透表面、居民地、水田、裸土4类地物识别适宜光谱分辨率为80nm,其余地物识别适宜光谱分辨率为160nm。以窄波段间的活跃度为指标进行融合,生成降维后的宽波段分别是21个波段和11个波段。8类地物在3尺度和4尺度下的分类结果说明降维影像能满足应用需求,提出的降维方法可行。 相似文献
19.
The effect of soil moisture content on vegetation and therefore on growth is well known. Information about the growth of forest stands is key in forest planning and management, and is the concern of various stakeholders. One way to assess moisture content and its impacts on forest growth is to apply the Topographic Wetness Index (TWI) and the derived terrain attributes from the Digital Terrain Model (DTM). The TWI is an important terrain attribute, used in various ecological studies. In the current study, a total of 9987 tally trees within 197 sample plots in southeastern Finland and LiDAR (Light Detection and Ranging) −based TWI were selected to examine: 1) the effect of cell resolutions and focal statistics of neighborhood cells of DTM, on tree diameter increment, and 2) possibilities to improve the prediction accuracy of an existing single-tree growth model using the terrain attributes and TWI with the combined effects of three characteristics (i.e., cell resolutions, neighborhood cells and terrain attributes). The results suggest that the TWI with terrain attributes improved the growth estimation significantly, and within different site types the Root Mean Square Errors (RMSE) were lowered substantially. The best results were obtained for birch trees. The higher resolution of the DTM and the lower focal neighborhood cells were found to be the best alternative in computing the TWI. 相似文献
20.
In this study, a high spectral resolution GER-2600 spectroradiometer was used to obtain the spectral data of soil samples that were polluted with four different types of petroleum–hydrocarbons products: Diesel, Gasoline, Crude Oil and Fuel Oil. The polluted soil samples were prepared in the laboratory at five concentrations levels: unpolluted soil, 2500, 100,000, 250,000 ppm and pure pollutant. Spectral data were pre-processed and then analysed with various approaches: Principal Components Transformation and ANOVA, Spectral Angle Mapper (SAM), Hydrocarbon Index (HI) and Spectral Mixture Analysis (SMA). The results showed that it was possible to determine the different spectral response between clean soil and some of the polluted soils: crude oil at concentrations higher than 100,000 ppm were the easiest to recognize; while samples polluted with gasoline at concentrations below 250,000 ppm were the most difficult to distinguish from non-polluted samples. 相似文献