共查询到20条相似文献，搜索用时 31 毫秒
1.
On aggregation in spatial econometric modelling 总被引：1，自引：1，他引：0
Jean H.P. Paelinck 《Journal of Geographical Systems》2000,2(2):157-165
The spatial aggregation problem – also termed the modifiable areal unit problem – has attracted regular attention in spatial
statistics and econometrics. In this study econometric aggregation analysis is used to investigate the formal composition
of meso-areal parameters given micro-areal underlying relations with spatial dependence. Impact on stochastic terms (possible
meso-areal spatial autocorrelation) is also studied. Finally consequences for meso-areal estimation are derived, the general
finding having been that spatial aggregation leads to meso-region specific parameter values, with the estimation problems
this implies. 相似文献
2.
Yukio Sadahiro 《Journal of Geographical Systems》1999,1(2):107-136
This paper develops statistical methods for analyzing the distribution of spatial objects—points, convex polygons, and line
segments—in relation to a surface. We propose statistics for measuring the relationship between the distribution of these
objects and a surface and derive their expectations and variances under the null hypothesis that the objects are independently
and randomly distributed. The statistics are approximately distributed according to the normal distribution under the null
hypothesis, which enables us to test the significance of the spatial relationships statistically. Using the proposed methods,
we empirically analyze the distribution of convenience stores in relation to the distribution of population in a suburb of
Osaka, Japan. Some empirical findings are shown. 相似文献
3.
This paper describes a procedure for extending local statistics to categorical spatial data. The approach is based on the notion that there are two fundamental characteristics of categorical spatial data; composition and configuration. Further, it is argued that, when considered locally, the latter should be measured conditionally with respect to the former. These ideas are developed for binary, gridded data. Local composition is measured by counting the numbers of cells of a particular type, while local configuration is measured by join counts. The approach is illustrated using a small, empirical data set and an ad hoc procedure is developed to deal with the impact of global spatial autocorrelation on the local statistics.The author gratefully acknowledges financial support from the GEOIDE Network of Centres of Excellence (ENV #4) and the helpful comments of three anonymous reviewers. 相似文献
4.
Márcio Poletti Laurini 《Journal of Geographical Systems》2017,19(4):371-398
We propose a spatial error model with continuous random effects based on Matérn covariance functions and apply this model for the analysis of income convergence processes (\(\beta \)-convergence). The use of a model with continuous random effects permits a clearer visualization and interpretation of the spatial dependency patterns, avoids the problems of defining neighborhoods in spatial econometrics models, and allows projecting the spatial effects for every possible location in the continuous space, circumventing the existing aggregations in discrete lattice representations. We apply this model approach to analyze the economic growth of Brazilian municipalities between 1991 and 2010 using unconditional and conditional formulations and a spatiotemporal model of convergence. The results indicate that the estimated spatial random effects are consistent with the existence of income convergence clubs for Brazilian municipalities in this period. 相似文献
5.
《International Journal of Digital Earth》2013,6(3):203-218
Abstract While data like HJ-1 CCD images have advantageous spatial characteristics for describing crop properties, the temporal resolution of the data is rather low, which can be easily made worse by cloud contamination. In contrast, although Moderate Resolution Imaging Spectroradiometer (MODIS) can only achieve a spatial resolution of 250 m in its normalised difference vegetation index (NDVI) product, it has a high temporal resolution, covering the Earth up to multiple times per day. To combine the high spatial resolution and high temporal resolution of different data sources, a new method (Spatial and Temporal Adaptive Vegetation index Fusion Model [STAVFM]) for blending NDVI of different spatial and temporal resolutions to produce high spatial–temporal resolution NDVI datasets was developed based on Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). STAVFM defines a time window according to the temporal variation of crops, takes crop phenophase into consideration and improves the temporal weighting algorithm. The result showed that the new method can combine the temporal information of MODIS NDVI and spatial difference information of HJ-1 CCD NDVI to generate an NDVI dataset with both high spatial and high temporal resolution. An application of the generated NDVI dataset in crop biomass estimation was provided. An average absolute error of 17.2% was achieved. The estimated winter wheat biomass correlated well with observed biomass (R 2 of 0.876). We conclude that the new dataset will improve the application of crop biomass estimation by describing the crop biomass accumulation in detail. There is potential to apply the approach in many other studies, including crop production estimation, crop growth monitoring and agricultural ecosystem carbon cycle research, which will contribute to the implementation of Digital Earth by describing land surface processes in detail. 相似文献
6.
The neighborhood effects of foreclosure 总被引：1，自引：0，他引：1
Neighborhood quality is an important attribute of housing yet its value is rarely known to researchers. We argue that changes
in nearby foreclosures reveal changes in neighborhood quality. Thus estimates of the hedonic price of nearby foreclosures
provide a glimpse of values that people hold for local neighborhood quality. The empirical models include controls for both
spatial dependence in housing prices and in the errors. The estimates indicate that nearby foreclosures produce externalities
that are capitalized into home prices—an additional foreclosure within 250 feet of a sale negatively impacts selling price
by approximately $1,666, ceteris paribus. 相似文献
7.
Area-based tests for association between spatial patterns 总被引：2，自引：0，他引：2
Edge effects pervade natural systems, and the processes that determine spatial heterogeneity (e.g. physical, geochemical,
biological, ecological factors) occur on diverse spatial scales. Hence, tests for association between spatial patterns should
be unbiased by edge effects and be based on null spatial models that incorporate the spatial heterogeneity characteristic
of real-world systems. This paper develops probabilistic pattern association tests that are appropriate when edge effects
are present, polygon size is heterogeneous, and the number of polygons varies from one classification to another. The tests
are based on the amount of overlap between polygons in each of two partitions. Unweighted and area-weighted versions of the
statistics are developed and verified using scenarios representing both polygon overlap and avoidance at different spatial
scales and for different distributions of polygon sizes. These statistics were applied to Soda Butte Creek, Wyoming, to determine
whether stream microhabitats, such as riffles, pools and glides, can be identified remotely using high spatial resolution
hyperspectral imagery. These new “spatially explicit” techniques provide information and insights that cannot be obtained
from the spectral information alone.
Received 1 June 2001 / Accepted 25 October 2001 相似文献
8.
Area-to-point Kriging in spatial hedonic pricing models 总被引：4，自引：1，他引：3
This paper proposes a geostatistical hedonic price model in which the effects of location on house values are explicitly modeled.
The proposed geostatistical approach, namely area-to-point Kriging with External Drift (A2PKED), can take into account spatial
dependence and spatial heteroskedasticity, if they exist. Furthermore, this approach has significant implications in situations
where exhaustive area-averaged housing price data are available in addition to a subset of individual housing price data.
In the case study, we demonstrate that A2PKED substantially improves the quality of predictions using apartment sale transaction
records that occurred in Seoul, South Korea, during 2003. The improvement is illustrated via a comparative analysis, where
predicted values obtained from different models, including two traditional regression-based hedonic models and a point-support
geostatistical model, are compared to those obtained from the A2PKED model. 相似文献
9.
Arif Wismadi Mark Zuidgeest Mark Brussel Martin van Maarseveen 《Journal of Geographical Systems》2014,16(1):19-48
To determine whether the inclusion of spatial neighbourhood comparison factors in Preference Modelling allows spatial decision support systems (SDSSs) to better address spatial equity, we introduce Spatial Preference Modelling (SPM). To evaluate the effectiveness of this model in addressing equity, various standardisation functions in both Non-Spatial Preference Modelling and SPM are compared. The evaluation involves applying the model to a resource location-allocation problem for transport infrastructure in the Special Province of Yogyakarta in Indonesia. We apply Amartya Sen’s Capability Approach to define opportunity to mobility as a non-income indicator. Using the extended Moran’s I interpretation for spatial equity, we evaluate the distribution output regarding, first, ‘the spatial distribution patterns of priority targeting for allocation’ (SPT) and, second, ‘the effect of new distribution patterns after location-allocation’ (ELA). The Moran’s I index of the initial map and its comparison with six patterns for SPT as well as ELA consistently indicates that the SPM is more effective for addressing spatial equity. We conclude that the inclusion of spatial neighbourhood comparison factors in Preference Modelling improves the capability of SDSS to address spatial equity. This study thus proposes a new formal method for SDSS with specific attention on resource location-allocation to address spatial equity. 相似文献
10.
Modeling network autocorrelation within migration flows by eigenvector spatial filtering 总被引：8，自引：5，他引：3
Yongwan Chun 《Journal of Geographical Systems》2008,10(4):317-344
Although the assumption of independence among interaction flows frequently is engaged in spatial interaction modeling, in
many circumstances it leads to misspecified models and incorrect inferences. An informed approach is to explicitly incorporate
an assumed relationship structure among the interaction flows, and to explicitly model the network autocorrelation. This paper
illustrates such an approach in the context of U.S. interstate migration flows. Behavioral assumptions, similar to those of
the intervening opportunities or the competing destinations concepts, exemplify how to specify network flows that are related
to particular origin–destination combinations. The stepwise incorporation of eigenvectors, which are extracted from a network
link matrix, captures the network autocorrelation in a Poisson regression model specification context. Spatial autocorrelation
in Poisson regression is measured by the test statistic of Jacqmin-Gadda et al. (Stat Med
16(11):1283–1297, 1997). Results show that estimated regression parameters in the spatial filtering interaction model become
more intuitively interpretable.
相似文献
| Yongwan ChunEmail: |
11.
Spatial statistical techniques for aggregating point objects extracted from high spatial resolution remotely sensed imagery 总被引：3，自引：0，他引：3
Trisalyn Nelson K. Olaf Niemann Michael A. Wulder 《Journal of Geographical Systems》2002,4(4):423-433
Using a local maximum filter, individual trees were extracted from a 1 m spatial resolution IKONOS image and represented
as points. The spatial pattern of individual trees was determined to represent forest age (a surrogate for forest structure).
Point attributes, based on the spatial pattern of trees, were generated via nearest neighbour statistics and used as the basis
for aggregating points into forest structure units. The forest structure units allowed for the mapping of a forested area
into one of three age categories: young (1–20 years), intermediate (21–120 years), and mature (>120 years). This research
indicates a new approach to image processing, where objects generated from the processing of image data (rather than pixels
or spectral values) are subjected to spatial statistical analysis to estimate an attribute relating an aspect of forest structure.
Received: 22 April 2002 / Accepted: 23 November 2002 相似文献
12.
13.
Spatial cluster detection techniques are widely used in criminology, geography, epidemiology, and other fields. In particular,
spatial scan statistics are popular and efficient techniques for detecting areas of elevated crime or disease events. The
majority of spatial scan approaches attempt to delineate geographic zones by evaluating the significance of clusters using
likelihood ratio statistics tested with the Poisson distribution. While this can be effective, many scan statistics give preference
to circular clusters, diminishing their ability to identify elongated and/or irregular shaped clusters. Although adjusting
the shape of the scan window can mitigate some of these problems, both the significance of irregular clusters and their spatial
structure must be accounted for in a meaningful way. This paper utilizes a multiobjective evolutionary algorithm to find clusters
with maximum significance while quantitatively tracking their geographic structure. Crime data for the city of Cincinnati
are utilized to demonstrate the advantages of the new approach and highlight its benefits versus more traditional scan statistics. 相似文献
14.
Spatial discretisation plays an important role in many numerical environmental models. This paper studies the control of spatial discretisation in coastal oil spill modelling with a view to assure the quality of modelling outputs for given spatial data inputs. Spatial data analysis techniques are effective for investigating and improving the spatial discretisation in different phases of the modelling. Proposed methods are implemented and tested with experimental models. A new “Automatic Search” method based on GIS zone design principles is shown to significantly improve discretisation of bathymetric data and hydrodynamic modelling outputs. The concepts and methods developed in the study are expected to have general relevance for a range of applications in numerical environmental modelling. 相似文献
15.
ADCN: An anisotropic density‐based clustering algorithm for discovering spatial point patterns with noise 
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下载免费PDF全文 Density‐based clustering algorithms such as DBSCAN have been widely used for spatial knowledge discovery as they offer several key advantages compared with other clustering algorithms. They can discover clusters with arbitrary shapes, are robust to noise, and do not require prior knowledge (or estimation) of the number of clusters. The idea of using a scan circle centered at each point with a search radius Eps to find at least MinPts points as a criterion for deriving local density is easily understandable and sufficient for exploring isotropic spatial point patterns. However, there are many cases that cannot be adequately captured this way, particularly if they involve linear features or shapes with a continuously changing density, such as a spiral. In such cases, DBSCAN tends to either create an increasing number of small clusters or add noise points into large clusters. Therefore, in this article, we propose a novel anisotropic density‐based clustering algorithm (ADCN). To motivate our work, we introduce synthetic and real‐world cases that cannot be handled sufficiently by DBSCAN (or OPTICS). We then present our clustering algorithm and test it with a wide range of cases. We demonstrate that our algorithm can perform equally as well as DBSCAN in cases that do not benefit explicitly from an anisotropic perspective, and that it outperforms DBSCAN in cases that do. Finally, we show that our approach has the same time complexity as DBSCAN and OPTICS, namely O(n log n) when using a spatial index and O(n2) otherwise. We provide an implementation and test the runtime over multiple cases. 相似文献
16.
The Spatial Interaction Model proposed by Alonso as “Theory of Movements” offers an innovative specification of spatial origin-destination
flow models. Equations for flows between regions, total outflow from and total inflow to a region are linked by balancing
factors. This paper presents a consistent formulation of Spatial Interaction Models in the Wilson tradition and Alonso's Theory
of Movements. The paper is intended as an introduction to the model and a review of␣the state of the art. Besides it is argued
that simultaneous equation techniques are required to estimate the so-called systemic parameters.
Received: 21 May 2000 / Accepted: 18 January 2001 相似文献
17.
Selectivity estimation is crucial for query optimizers choosing an optimal spatial execution plan in a spatial database management system.This paper presents an Annular Bucket spatial histogram(AB histogram)that can estimate the selectivity in finer spatial selection and spatial join operations even when the spatial query has more operators or more joins.The AB histogram is represented as a set of bucket-range,bucket-count value pairs.The bucket-range often covers an annular region like a sin-gle-cell-sized photo frame.The bucket-count is the number of objects whose Minimum Bounding Rectangles(MBRs)fall between outer rectangle and inner rectangle of the bucket-range.Assuming that all MBRs in each a bucket distribute evenly,for every buck-et,we can obtain serial probabilities that satisfy a certain spatial selection or join conditions from the operations’ semantics and the spatial relations between every bucket-range and query ranges.Thus,according to some probability theories,spatial selection or join selectivity can be estimated by the every bucket-count and its probabilities.This paper also shows a way to generate an updated AB histogram from an original AB histogram and those probabilities.Our tests show that the AB histogram not only supports the selectivity estimation of spatial selection or spatial join with "disjoint","intersect","within","contains",and "overlap" operators but also provides an approach to generate a reliable updated histogram whose spatial distribution is close to the distribution of ac-tual query result. 相似文献
18.
Giuseppe Arbia 《Journal of Geographical Systems》2001,3(3):271-281
Economists have recently devoted an increasing attention to the issue of spatial concentration of economic activities. However,
surprisingly enough, most of the empirical work is still based on the computation of very basic statistical measures in which
the geographical characteristics of data play no role. By making use of a series of empirical examples we show that spatial
concentration consists of two different features that are rarely kept as separate in the statistical analysis: an a-spatial
concept of variability which is invariant to permutations, and the concept of polarization that refers to the geographical
position of observations.
Received: 8 August 2000 / Accepted: 20 June 2001 相似文献
19.
Traditional methods of recording fire burned areas and fire severity involve expensive and time-consuming field surveys. Available remote sensing technologies may allow us to develop standardized burn-severity maps for evaluating fire effects and addressing post fire management activities. This paper focuses on multiscale characterization of fire severity using multisensor satellite data. To this aim, both MODIS (Moderate Resolution Imaging Spectroradiometer) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data have been processed using geo-statistic analyses to capture pattern features of burned areas.Even if in last decades different authors tried to integrate geo-statistics and remote sensing image processing, methods used since now are only variograms, semivariograms and kriging. In this paper, we propose an approach based on the use of spatial indicators of global and local autocorrelation. Spatial autocorrelation statistics, such as Moran's I and Getis–Ord Local Gi index, were used to measure and analyze dependency degree among spectral features of burned areas. This approach enables the characterization of pattern features of a burned area and improves the estimation of fire severity. 相似文献
20.
植被净初级生产力NPP(Net Primary Production)遥感估算与分析,有赖于高时空分辨率的遥感数据,但目前中高分辨率的遥感数据受卫星回访周期及天气的影响,在中国南方地区难以获取连续时间序列的数据,从而影响了高精度的区域植被净初级生产力的遥感估算。为此,提出一种基于多源遥感数据时空融合技术与CASA模型估算高时空分辨率NPP的方法。首先,利用多源遥感数据,即Landsat8 OLI数据与MODIS13Q1数据,采用遥感数据时空融合方法,获得了时间序列的Landsat8 OLI融合数据;然后,基于Landsat8 OLI时空融合数据,并采用CASA模型,以长株潭城市群核心区为例,进行区域植被NPP的遥感估算。研究结果表明,基于时间序列Landsat融合数据估算的30m分辨率的NPP具有良好的空间细节信息,且估算值与实测值的相关系数达0.825,与实测NPP数据保持了较好的一致性。 相似文献