共查询到20条相似文献，搜索用时 31 毫秒
1.
基于栅格数据空间分析的城镇土地定级研究 总被引：2，自引：0，他引：2
以四川省达州市城区土地定级为例,论述了栅格数据空间分析方法在城镇土地定级中的运用,如定级单元的划分、定级过程中各种距离的求取、定级单元各要素作用分及总作用分的计算以及各定级要素作用分等值线的绘制。结果表明,基于栅格数据的空间分析方法在城镇土地定级中有十分重要的作用,有广泛的应用前景。 相似文献
2.
Alex Hagen-Zanker 《Journal of Geographical Systems》2006,8(2):165-185
Methods for map comparison such as the Kappa and Tau statistics have grown popular in applications of remote sensing accuracy assessment. These methods take pairs of raster maps as sets of paired observations and do not consider spatial structure except for cell-by-cell overlap. In contrast, landscape structure metrics such as mean patch size that are commonly used in landscape ecology do express spatial structure, however without addressing cell-by-cell overlap. This paper introduces a number of comparison methods that consider spatial structure and overlap simultaneously. They achieve this by involving the neighbourhood of a cell in the calculation of similarity at its location. For this, the methods make use of a distance weighted moving window. Two test cases demonstrate that the different comparison methods offer a spatial account of varied aspects of map similarity. It is found that the methods can best be used in conjunction with a visual analysis; they then serve to quantify, reject or confirm hypotheses. 相似文献
3.
组合核支持向量回归提取高光谱影像不透水面 总被引：1，自引：0，他引：1
由于城市地表组成的复杂性,基于单核函数的支持向量回归模型很难满足精度。本文结合空间-光谱组合核函数和支持向量回归,提出了一种提取高光谱影像不透水面丰度的改进算法。首先从高光谱遥感图像上提取波谱特征和多通道灰度共生矩阵空间纹理特征,选取研究区10%像元特征数据作为训练数据,以线性加权求和核为多核组合方式,建立结合光谱信息和空间信息的组合核支持向量回归模型。然后,用生成的回归模型预测未知像元不透水面丰度值。最后,对实验结果进行评价。在模拟数据试验中,本文算法比单核回归均方根误差平均降低1.4%,决定系数比单核回归平均提高0.6%。在Hyperion数据两组试验中,该算法比单核回归均方根误差平均降低1.8%,决定系数比单核回归平均提高11.7%。模拟和真实两种高光谱数据实验中,本文算法均得到了空间形态上更准确的不透水面结果,单核回归结果存在失真现象。研究结果表明:本文算法能够有效提取城市不透水面丰度,与单核方法相比有较明显的精度提升。 相似文献
4.
为了克服超分辨重建后的遥感图像空间分辨率的界定还采用人工对比判读存在误差和结论不统一的缺点,利用调制传递函数、奈奎斯特采样定理和人眼极限频率,建立了一种新的空间分辨率客观评价方法。利用该方法计算超分辨率重建后的遥感图像相比原始遥感图像空间分辨率的提高倍数,从而推断出重建后遥感图像的空间分辨率的大小。在数值测试中,利用不同的超分辨率方法对分级变频矩形光栅图像进行重建,采用提出的空间分辨率评价方法,与归一化均方误差、峰值信噪比、信息熵、灰度平均梯度进行客观评价的结果一致。此方法为遥感图像空间分辨率改进值的计算提供了一种可行的量化模型。 相似文献
5.
作为区域连续运行参考系统(CORS)反演大气可降水量的关键参数——大气加权平均温度,时空特性明显。为了提高区域CORS反演大气可降水量的精度和可靠性,利用青岛探空站2009-2011年3年的探空数据,分析得到地表温度Ts与加权平均温度Tm的相关系数R为0.877 6,为强线性相关;采用回归分析建立了青岛地区加权平均温度模型;利用该模型计算青岛地区2012年加权平均温度,与由探空数据计算的加权平均温度的平均偏差、标准差和均方根误差分别为0.307 K、3.359 K和3.384 K;将该模型应用在青岛CORS反演大气可降水量的计算中,与临近探空站计算的大气可降水汽相比,平均偏差、标准差和均方根误差分别为0.70 mm、3.48 mm和3.53 mm.研究表明,应用区域探空数据建立加权平均温度模型具有可行性,并可以在一定程度上提高区域CORS反演大气可降水量的精度和可靠性。 相似文献
6.
Delaunay三角网支持下的空间场表达 总被引：6，自引：1，他引：6
不规则三角网TIN本质上属于基于场的空间数据模型,然而在GIS领域,通常将其局限于DTM数字地形模型的表达中,没有象规则栅格模型那样在平面实体及实体关系表达中发挥足够的作用。针对这一局限性,仿照规则格网的栅格数据模型,应用DELAUNAY三角网工具,建立一种面向平面空间场表达的形式化数据模型。应用三角形的3种基元:顶点、边、三角形面表达空间点、线、面目标,定义该模型上的3种操作:扩充、收缩与骨架化,并进一步推广到序惯操作与条件操作。在几个应用实例基础上,分析该模型在空间邻近关系表达上可发挥重要作用。 相似文献
7.
一体化空间数据结构及其索引机制研究 总被引：17，自引：1，他引：16
本文提出了一种新的栅矢一体化空间数据结构,该结构采用三级划分策略及几何目标元子充填表达技术,使空间数据栅格化的同时,也能满足精度要求。同时引入弧段栅格比特阵和面要素自适应空间索引结构,有效地提高了空间检索效率。试验证明,上述理论及方法是可行的。 相似文献
8.
Cumulative spatial impact layers: A novel multivariate spatio‐temporal analytical summarization tool
Lucy Romeo Jake Nelson Patrick Wingo Jennifer Bauer Devin Justman Kelly Rose 《Transactions in GIS》2019,23(5):908-936
Scientific inquiry often requires analysis of multiple spatio‐temporal datasets, ranging in type and size, using complex multi‐step processes demanding an understanding of GIS theory and software. Cumulative spatial impact layers (CSIL) is a GIS‐based tool that summarizes spatio‐temporal datasets based on overlapping features and attributes. Leveraging a recursive quadtree method, and applying multiple additive frameworks, the CSIL tool allows users to analyze raster and vector datasets by calculating data, record, or attribute density. Providing an efficient and robust method for summarizing disparate, multi‐format, multi‐source geospatial data, CSIL addresses the need for a new integration approach and resulting geospatial product. The built‐in flexibility of the CSIL tool allows users to answer a range of spatially driven questions. Example applications are provided in this article to illustrate the versatility and variety of uses for this CSIL tool and method. Use cases include addressing regulatory decision‐making needs, economic modeling, and resource management. Performance reviews for each use case are also presented, demonstrating how CSIL provides a more efficient and robust approach to assess a range of multivariate spatial data for a variety of uses. 相似文献
9.
变形监测数据处理的方法有很多,但这些方法对数据量及数据的采集方式有特定的要求,或者计算过程复杂。针对这些问题,提出了基于变窗宽核加权估计的变形趋势拟合方法,即先用较大窗宽的核加权估计去拟合变形的整体趋势,再用较小窗宽的核加权估计去拟合残余变形量——局部趋势。并针对这一新方法,提出了一种新的窗宽计算方法,即时序间隔标准差窗宽。以某大坝某一监测点32期的高程变形拟合为例,比较了不同的窗宽以及不同变窗宽组合的核加权拟合效果。结果表明,采用时序间隔标准差窗宽的核加权拟合比经验窗宽的拟合精度高;而基于变窗宽的核加权拟合比前两者精度更高。 相似文献
10.
双线性插值近似网格的栅格数据投影变换 总被引：1，自引：0，他引：1
在栅格数据投影变换常用算法的基础上,介绍一种新的基于双线性内插近似网格算法的栅格数据投影变换,并详细描述其算法过程,认真分析其特点,并证明该算法在大范围栅格数据投影变换中有显著优点。 相似文献
11.
12.
《地理信息系统科学与遥感》2013,50(3):273-288
This study deals with the issue of extreme coefficients in geographically weighted regression (GWR) and their effects on mapping coefficients using three datasets with different spatial resolutions. We found that although GWR yields extreme coefficients regardless of the resolution of the dataset or types of kernel function: (1) GWR tends to generate extreme coefficients for less spatially dense datasets; (2) coefficient maps based on polygon data representing aggregated areal units are more sensitive to extreme coefficients; and (3) coefficient maps using bandwidths generated by a fixed calibration procedure are more vulnerable to the extreme coefficients than adaptive calibration. 相似文献
13.
An empirical study was performed assessing the accuracy of land use change detection when using satellite image data acquired ten years apart by sensors with differing spatial resolutions. Landsat/Multi‐spectral Scanner (MSS) with Landsat/Thematic Mapper (TM) or SPOT/High Resolution Visible (HRV) multi‐spectral (XS) data were used as a multi‐data pair for detecting land use change. The primary objectives of the study were to: (1) compare standard change detection methods (e.g. multi‐date ratioing and principal components analysis) applied to image data of varying spatial resolution; (2) assess whether to transform the raster grid of the higher resolution image data to that of the lower resolution raster grid or vice‐versa in the registration process: and (3) determine if Landsat/TM or SPOT/ HRV(XS) data provides more accurate detection of land use changes when registered to historical Landsat/MSS data. Ratioing multi‐sensor, multi‐date satellite image data produced higher change detection accuracies than did principal components analysis and is useful as a land use change enhancement technique. Ratioing red and near infrared bands of a Landsat/MSS‐SPOT/HRV(XS) multi‐date pair produced substantially higher change detection accuracies (～10%) than ratioing similar bands of a Landsat/MSS ‐ Landsat/TM multi‐data pair. Using a higher‐resolution raster grid of 20 meters when registering Landsat/MSS and SPOTZHRV(XS) images produced a slightly higher change detection accuracy than when both images were registered to an 80 meter raster grid. Applying a “majority”; moving window filter whose size approximated a minimum mapping unit of 1 hectare increased change detection accuracies by 1–3% and reduced commission errors by 10–25%. 相似文献
14.
Least-squares collocation with covariance-matching constraints 总被引：1，自引：0，他引：1
Christopher Kotsakis 《Journal of Geodesy》2007,81(10):661-677
Most geostatistical methods for spatial random field (SRF) prediction using discrete data, including least-squares collocation
(LSC) and the various forms of kriging, rely on the use of prior models describing the spatial correlation of the unknown
field at hand over its domain. Based upon an optimal criterion of maximum local accuracy, LSC provides an unbiased field estimate
that has the smallest mean squared prediction error, at every computation point, among any other linear prediction method
that uses the same data. However, LSC field estimates do not reproduce the spatial variability which is implied by the adopted
covariance (CV) functions of the corresponding unknown signals. This smoothing effect can be considered as a critical drawback
in the sense that the spatio-statistical structure of the unknown SRF (e.g., the disturbing potential in the case of gravity
field modeling) is not preserved during its optimal estimation process. If the objective for estimating a SRF from its observed
functionals requires spatial variability to be represented in a pragmatic way then the results obtained through LSC may pose
limitations for further inference and modeling in Earth-related physical processes, despite their local optimality in terms
of minimum mean squared prediction error. The aim of this paper is to present an approach that enhances LSC-based field estimates
by eliminating their inherent smoothing effect, while preserving most of their local prediction accuracy. Our methodology
consists of correcting a posteriori the optimal result obtained from LSC in such a way that the new field estimate matches
the spatial correlation structure implied by the signal CV function. Furthermore, an optimal criterion is imposed on the CV-matching
field estimator that minimizes the loss in local prediction accuracy (in the mean squared sense) which occurs when we transform
the LSC solution to fit the spatial correlation of the underlying SRF. 相似文献
15.
Coupling land use allocation models with raster GIS 总被引：5，自引：0，他引：5
As geographic information systems (GIS) have moved from information storage and retrieval operations towards more decision
support functions, there is a need for more integration of spatial analytical modules that can assist in locational decisions.
This paper presents a methodology for coupling land use allocation models with a raster GIS. For raster systems, the integration
of any decision module has been limited by the size of raster datasets that may contain hundreds of thousands of pixels. Therefore,
decision heuristics have been used rather than exact methods such as mathematical programming models. For the problem of land
use allocation, the special structure of the generalized assignment problem is used here to handle large scale datasets. The
advantage of the mathematical programming approach is the additional information associated with the dual variables and opportunity
costs that can be used in subsequent sensitivity analyses.
Received: 7 April 1998/Accepted: 2 October 1998 相似文献
16.
Improving the Elevation Accuracy of Digital Elevation Models: A Comparison of Some Error Detection Procedures 总被引：1，自引：1，他引：0
Carlos López 《Transactions in GIS》2000,4(1):43-64
The widespread availability of powerful desktop computers, easy‐to‐use software tools and geographic datasets have raised the quality problem of input data to be a crucial one. Even though accuracy has been a concern in every serious application, there are no general tools for its improvement. Some particular ones exist, however, and some results are presented here for a particular case of quantitative raster data: Digital Elevation Models (DEM). Two procedures designed to detect anomalous values (also named gross errors, outliers or blunders) in DEMs, but valid also for other quantitative raster datasets, were tested. A DEM with elevations varying from 181 to 1044 m derived from SPOT data has been used as a contaminated sample, while a manually derived DEM obtained from aerial photogrammetry was regarded as the ground truth to allow a direct performance comparison for the methods with real errors. It is assumed that a “better” value can be measured or obtained through some methodology once an outlier location is suggested. The options are different depending upon the user (DEM producers might go to the original data and make another reading, while end users might use interpolation). Both choices were considered in this experiment. Preliminary results show that for the available dataset, the accuracy might be improved to some extent with very little effort. Effort is defined here as the percentage of points suggested by the methodology in relation with its total number: thus 100 per cent effort implies that all points have been checked. The method proposed by López (1997) gave poor results, because it has been designed for errors with low spatial autocorrelation (which is not the case here). A modified version was then designed and compared with the method proposed by Felicísimo (1994). The three procedures can be applied both for error detection during DEM generation and by end users, and they might be of use for other quantitative raster data. The choice of the best methodology is different depending on the effort involved. The conclusions have been derived for a photogrammetrically obtained DEM; other production procedures might lead to different results. 相似文献
17.
Migliaccio M. Nunziata F. Bruno F. Casu F. 《Geoscience and Remote Sensing Letters, IEEE》2007,4(3):397-400
Interferometric synthetic aperture radar processing requires interpolating a slave image onto a master one. Since the signals requiring interpolation are limited in both time and bandwidth, the Knab sampling window provides an almost optimal and viable interpolation kernel. Its performance in terms of coherence preservation and interferometric phase error as a function of the number of retained samples and oversampling factor are shown. 相似文献
18.
The key to develop 3-D GISs is the study on 3-D data model and data structure. Some of the data models and data structures have been presented by scholars. Because of the complexity of 3-D spatial phenomenon, there are no perfect data structures that can describe all spatial entities. Every data structure has its own advantages and disadvantages. It is difficult to design a single data structure to meet different needs. The important subject in the 3-D data models is developing a data model that has integrated vector and raster data structures. A special 3-D spatial data model based on distributing features of spatial entities should be designed. We took the geological exploration engineering as the research background and designed an integrated data model whose data structures integrats vector and raster data by adopting object-oriented technique. Research achievements are presented in this paper. 相似文献
19.
现有人口空间化方法多基于行政单元构建回归模型并分配格网单元人口,但分析单元的尺度差异引发模型迁移问题。同时,格网特征建模仅考虑格网自身属性,导致格网间空间关联被人为割裂。为此,基于随机森林模型提出一种顾及格网属性分级与空间关联的人口空间化方法。该方法在格网特征建模中:（1）基于自然断点法构造建筑区类别约束的夜间灯光分级特征,并在行政单元尺度统计各等级网格占比作为训练输入,以减小模型跨尺度误差;（2）利用核密度估计刻画邻域兴趣点（point of interest, POI）对当前格网人口分布的影响及距离衰减效应;（3）基于叠置分析统计不同类型建筑区轮廓包含的各类POI数量,提升特征建模精细度。选取武汉市作为实验区域,在街道尺度与WorldPop、GPW及中国公里网格人口数据集进行对比验证方法的有效性。结果表明,该方法的平均绝对值误差仅为对比数据集的1/6~1/3。此外,还探讨了特征构成、格网大小及核密度带宽对精度的影响。 相似文献
20.
E. Pardo-Iguzquiza V.F. Rodríguez-Galiano M. Chica-Olmo Peter M. Atkinson 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(3):337-346
The aim of this paper was to extend the method of downscaling cokriging for image fusion by making the method spatially adaptive in that the filter parameters (cokriging weights) can change across the image. The method can adapt itself to the usual statistical non-homogeneity (spatially variable mean, variance and correlation length) of a satellite sensor image that covers an area with different spatial patterns of geographical objects or different terrain types. The solution adopted was to estimate the models of covariances and cross-covariances (or semivariograms and cross-semivariograms) by the same procedure as described in Pardo-Iguzquiza et al. (2006) but with the method applied locally instead of globally. The correct implementation of this local estimation is the key for computational feasibility and prediction efficiency. Two parameters to be taken into account are the grid of locations on which a moving window is centred (local modelling is performed inside this window) and the size of this moving window. With respect to the latter parameter, there is a trade-off between a size small enough to make the procedure locally adaptive and large enough to produce reliable statistical estimates. The computational burden will impose limits to the distance between grid points on which the local moving window is centred. A case study with Landsat ETM+ images was used to show the implementation of the method and the result was evaluated using several statistics widely used for assessing the quality of a fused image, apart from its visual appearance. 相似文献