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1.
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.
Yongwan ChunEmail:
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2.
In this paper, we distinguish three constrained variants of the gravity model of spatial interaction: doubly constrained, production constrained and attraction constrained exponential gravity models. These model variants include origin- and/or destination-specific balancing factors that act as constraints to ensure that the estimated rows and columns of the flow data matrix sum to the observed row and column totals. Because flows are typically counts, the Poisson rather than the normal probability model specification furnishes the appropriate statistical distribution, and parameter estimation can be achieved via Poisson regression. This probability model specification motivates the use of origin and/or destination fixed effects or—under certain conditions—the use of origin- and/or destination-specific random effects for model estimation. The paper establishes theoretical connections between balancing factors, fixed effects represented by binary indicator variables and random effects. The results pertaining to both the doubly and singly constrained cases of spatial interaction are illustrated with an empirical example while accounting for spatial dependence between flows from locations neighbouring both the origins and destinations during estimation.  相似文献   

3.
An empirical test of the competing destinations model   总被引：2，自引：0，他引：2  
 It has long been believed that properties of spatial structure have a strong effect on trip distribution, which thus leads to a bias in the estimated distance decay parameters of spatial interaction models. This paper is an attempt to identify to what extent the spatial structure effect affects the trip distribution and determine whether the incorporation of a term to account for the relative location of destinations into the conventional gravity models, results in a model that can more correctly represent the actual trip distribution. The main focus is on the comparison of the origin–specific estimates of the distance decay parameter, calibrated from the traditional production-constrained model and the production-constrained competing destinations model. The results show that the competing destinations model is superior to the conventional model in both reproducing the interaction flows and giving behavioral explanation to the distance decay parameters, but the essential aim of the competing destinations model to remove the map pattern from the distance decay parameters of the conventional model has not been identified. Received: 5 September 2001 / Accepted: 17 June 2002 We are grateful to Gloria. A. Swieczkowski for kindly providing the migration data. The authors also gratefully acknowledge the comments of the referees.  相似文献   

4.
旅游流网络分析对理解游客的目的地选择以及目的地在旅游流网络中承担的角色有重要意义。以中国云南省为例,基于网络游记数据挖掘游客的多维度偏好,并以此对游客聚类,进而划分出不同类型的游客群体。针对各类游客游记中的旅游目的地序列建立旅游流网络,并从多个角度分析各类游客旅游流网络的结构特征和各目的地节点的角色特征。结果表明,不同类别游客的旅游流网络在整体结构上各有特点,反映出旅游目的地不同的空间交互模式和网络中心化程度。此外,部分旅游目的地在不同类别旅游流网络中承担截然相反的角色。上述分析有助于优化旅游流网络中各节点的协作机制,辅助旅游目的地制定差异化的旅游产品。  相似文献   

5.
Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

6.
Culture is gaining increasing importance in the modern tourism industry and represents a significant force of attraction for tourists (both domestic and international). Cultural tourism allows destinations and regions to expand their customer base, diversify their offer, extend the stay of the tourist, and reduce seasonality. Great efforts are made, by national governments and regions, in order to obtain official designation regarding the relevance of their historical/cultural attractions, for example through UNESCO’s World Heritage Sites (WHS) list. Such an aspect seems particularly relevant for a country like Italy, which has a high number of entries in the WHS list and where regions take an active role in promoting tourism. Using an 12-year panel of domestic tourism flows, we investigate the importance of the regional endowment in terms of WHS from two perspectives: (a) by separately estimating the effects, on tourism flows, of WHS located in the residence region of tourists and in the destination region; and (b) by taking into account potential spatial substitution/complementarity effects between regions due to their WHS endowment. Finally, a sensitivity analysis is offered to evaluate the spatial extent of the latter.  相似文献   

7.
Analyzing tourists' travel behavior at different stages of a trip can help to better understand their travel demands, providing valuable suggestions for destination management. In this article, we propose a research framework that can help in comprehensively analyzing tourists' travel behavior from the perspective of the three main stages: before, during, and after the trip. A case study was conducted based on user-generated content data from the Old Town of Lijiang to verify the feasibility of the proposed research framework. The results show that: (1) before the trip, tourists inquire about destinations and optimal stay; (2) during the trip, tourists are attracted to natural sceneries; (3) after the trip, tourists discuss experience and services. Travel behavior in stages provide detailed (inter-, intra-, and individual attractions) guidance (from tourists) for destinations. The proposed framework provides a novel perspective for exploring the spatiotemporal behavioral features of tourists at different stages of their trips.  相似文献   

8.
We introduce a Bayesian hierarchical regression model that extends the traditional least-squares regression model used to estimate gravity or spatial interaction relations involving origin-destination flows. Spatial interaction models attempt to explain variation in flows from n origin regions to n destination regions resulting in a sample of N = n 2 observations that reflect an n by n flow matrix converted to a vector. Explanatory variables typically include origin and destination characteristics as well as distance between each region and all other regions. Our extension introduces latent spatial effects parameters structured to follow a spatial autoregressive process. Individual effects parameters are included in the model to reflect latent or unobservable influences at work that are unique to each region treated as an origin and destination. That is, we estimate 2n individual effects parameters using the sample of N = n 2 observations. We illustrate the method using a sample of commodity flows between 18 Spanish regions during the 2002 period.  相似文献   

9.
Abstract

Waterholes are a key resource that influences wildlife distribution in semi-arid ecosystems. Mapping waterholes can guide intervening decisions for supplementing water resources and managing wildlife distribution patterns. Although remote sensing provides a key to mapping distribution of waterholes, efficiency of existing remotely sensed methods for detecting waterholes have to be evaluated and even new ones developed. In this study, we evaluated performance of the Modified Normalized Difference Water Index (MNDWI) and Superfine Water Index (SWI) at selected optimum thresholds. Kappa results indicated that MNDWI detects waterholes better than SWI. We further validated MNDWI detected waterholes by testing response of waterhole area to temporal rainfall variability and waterhole persistence to spatial rainfall variability. Extent of MNDWI-detected waterholes varied in relation to temporal rainfall variability (p < 0.05). Waterhole persistence was not associated with spatial rainfall variability which could be explained by differences in waterhole types or low spatial rainfall variability.  相似文献   

10.
ABSTRACT

Mapping spatial flow remains a challenge despite noticeable progress in recent years. This article presents a new, automated layout algorithm for spatial flow from one origin to multiple destinations. The algorithm triangulates the mapped space and builds a network from the triangles. It then simulates the formation of the dendritic drainage pattern of natural river systems and constructs an approximate Steiner tree by sequentially computing the shortest paths from the origin to the destinations using dynamically decreasing edge costs. A series of automatic cartographic operations, including edge simplification, straightening, smoothing, and rendering, then follow to improve the esthetics of the tree and to produce flow layouts that feature natural clusters and smooth edges. An experimental evaluation using four examples illustrates the effectiveness and adaptability of the algorithm with various spatial and parameter configurations. A quantitative comparison with existing methods on esthetics shows that the new algorithm generally renders destinations farther away from tree edges, which helps improve map readability but at the cost of longer total tree length. Evaluated with a smoothness index that rewards gradual tree splitting and smooth, natural, and straight edges, the proposed algorithm can achieve higher average edge smoothness and avoid the least smooth edges under various parameter settings.  相似文献   

11.
Numerous studies attempted to associate search engine data with travel behaviors. However, most existing studies focus on the destinations of search and travel, while ignoring the origins, which embed critical information of where the search requests were initiated and where the travelers came from. In this study, we explore the relationships between two types of intercity origin–destination flow data, namely travel flows and search flows, which, respectively, record the number of travelers and search requests from one city towards another. By comparing the two flows during holiday and non-holiday, we examine their complex spatiotemporal relationships from multiple perspectives, including time-lag effect, distance decay effect, spatial autocorrelation, network community, cities' rankings, and important factors of search and travel activities. The findings can deepen our understanding of search and travel behaviors, hence they can help decision makers to develop targeted strategies to enhance city's attractiveness, improve transportation infrastructure, and promote tourism.  相似文献   

12.
ABSTRACT

Taxi trajectories from urban environments allow inferring various information about the transport service qualities and commuter dynamics. It is possible to associate starting and end points of taxi trips with requirements of individual groups of people and even social inequalities. Previous research shows that due to service restrictions, boro taxis have typical customer destination locations on selected Saturdays: many drop-off clusters appear near the restricted zone, where it is not allowed to pick up customers and only few drop-off clusters appear at complicated crossing. Detected crossings imply recent infrastructural modifications. We want to follow up on these results and add one additional group of commuters: Citi Bike users. For selected Saturdays in June 2015, we want to compare the destinations of boro taxi and Citi Bike users. This is challenging due to manifold differences between active mobility and motorized road users, and, due to the fact that station-based bike sharing services are restricted to stations. Start and end points of trips, as well as the volumes in between rely on specific numbers of bike sharing stations. Therefore, we introduce a novel spatiotemporal assigning procedure for areas of influence around static bike sharing stations for extending available computational methods.  相似文献   

13.
Adaptive zoning is a recently introduced method for improving computer modeling of spatial interactions and movements in the transport network. Unlike traditional zoning, where geographic locations are defined by one single universal plan of discrete land parcels or ‘zones’ for the study area, adaptive zoning establishes a compendium of different zone plans, each of which is applicable to one journey origin or destination only. These adaptive zone plans are structured to represent strong spatial interactions in proportionately more detail than weaker ones. In recent articles, it has been shown that adaptive zoning improves, by a large margin, the scalability of models of spatial interaction and road traffic assignment. This article confronts the method of adaptive zoning with an application of the scale and complexity for which it was intended, namely an application of mode choice modeling that at the same time requires a large study area and a fine‐grained zone system. Our hypothesis is that adaptive zoning can significantly improve the accuracy of mode choice modeling because of its enhanced sensitivity to the geographic patterns and scales of spatial interaction. We test the hypothesis by investigating the performance of three alternative models: (1) a spatially highly detailed model that is permissible to the maximum extent by available data, but requires a high computational load that is generally out of reach for rapid turnaround of policy studies; (2) a mode choice model for the same area, but reducing the computational load by 90% by using a traditional zone system consisting of fewer zones; and (3) a mode choice model that also reduces the computational load by 90%, but based on adaptive zoning instead. The tests are carried out on the basis of a case study that uses the dataset from the London Area Transport Survey. Using the first model as a benchmark, it is found that for a given computational load, the model based on adaptive zoning contains about twice the amount of information of the traditional model, and model parameters on adaptive zoning principles are more accurate by a factor of six to eight. The findings suggest that adaptive zoning has a significant potential in enhancing the accuracy of mode choice modeling at the city or city‐region scale.  相似文献   

14.
Effects of scale in spatial interaction models   总被引：1，自引：0，他引：1  
We study the effects of aggregation on four different cases of nonlinear spatial gravity models. We present some theoretical results on the relationship between the mean flows at an aggregated level and the mean flow at the disaggregated level. We then focus on the case of perfect aggregation (scale problem) showing some results based on the theoretical expressions previously derived and on some artificial data. The main aim is to test the effects on the aggregated flows of the spatial dependence observed in the origin and in the destination variables. We show that positive spatial dependence in the origin and destination variables moderate the increase of the mean flows connatural with aggregation while negative spatial dependence exacerbates it.  相似文献   

15.
Obtaining spatial similarity degrees among the same objects on multi-scale maps is of importance in map generalization. This paper firstly defines the concepts of ‘map scale change’ and ‘spatial similarity degree’; then it proposes a model for calculating the spatial similarity degree between a river basin network at one scale and its generalized version at another scale. After this, it validates the new model and gets 16 points in the model validation process. The x-coordinate and y-coordinate of each point are map scale change and spatial similarity degree, respectively. Last, a formula for calculating spatial similarity degree taking map scale change as the only variable is obtained by the curve fitting method. The formula along with the model can be used to automate the algorithms for simplifying river basin networks.  相似文献   

16.
The field of GIS (S for Systems, Sciences, Services, and Studies) is at a cross‐road in the early 2010s. Aiming to link the multiple visions for the next phase of GIS development, this article suggests that the emerging open GIS should serve as a guiding concept. Contextualized in the broader literature of open science, this article proposes open GIS should include eight dimensions related to data, software, hardware, standards, research, publication, funding, and education. For the GIS community, open GIS offers four exciting opportunities: (1) technology‐driven opportunities for addressing challenges posed by the (spatial) big data deluge; (2) application‐led opportunities for confronting the problems of a rapidly changing planet; (3) curiosity‐inspired, crowd‐powered opportunities for the development of an open and geographic citizen science; and (4) education‐focused opportunities for implementing the vision of a spatial university. Although there are academic, legal, social/political, and environmental impediments for the practice of open GIS, open GIS will become increasingly important in shaping our research and educational agendas in the future.  相似文献   

17.
自驾游以自主性、灵活性、选择性以及多样性等内在特点吸引着许多人,而它的线路设计质量直接影响自驾游者的心理满意度。通过收集、梳理河南省优秀旅游资源的空间分布、景区详情、交通道路等信息,依据旅游学中旅游行为空间模式、数学中图论和旅行商问题、地理信息系统(GIS)等科学理论,设计河南省自助游的最佳旅游线路。本研究以具有河南代表性的旅游景区为实际空间数据源,以ArcGIS系统为空间分布、交通等属性信息的可视化工具,以图论和旅行商问题为路线设计的数学基础,构建出自驾游线路设计的模式。本研究方法简单科学,为广大自驾游者规划旅游线路提供了有实际意义的参考。  相似文献   

18.
 A rule-based model for managing uncertainty in spatial databases is presented. The overall goal of the model is to allow a user to assign to a single map class each polygon whose class is not entirely certain using more information than only the map class attributes of such polygons (that are herein termed abjects). This situation might arise when multiple map realizations of an area are available and interpreters/cartographers are not in agreement as to what class is present at a given location or when a digital image is classified by algorithmic/probabilistic means. The scale-based model developed relies on attribute, geometric, and neighborhood measures of abjects arranged in a hierarchical rule-based structure. Structural knowledge of these measures leads to the procedural knowledge that determines what action – e.g., merge, reclassify, retain – is to be taken for a given abject. The wider applicability of the model and associated methodology is also discussed. Received: 5 July 2001 / Accepted: 11 April 2002  相似文献   

19.
Spatial libraries are core components in many geographic information systems, spatial database systems, and spatial data science projects. These libraries provide the implementation of spatial type systems that include spatial data types and a large diversity of geometric operations. Their focus relies on handling crisp spatial objects, which are characterized by an exact location and a precisely defined extent, shape, and boundary in space. However, there is an increasing interest in analyzing spatial phenomena characterized by fuzzy spatial objects, which have inexact locations, vague boundaries, and/or blurred interiors. Unfortunately, available spatial libraries do not provide support for fuzzy spatial objects. In this article, we describe the R package named fsr, which is based on the Spatial Plateau Algebra and is publicly available at https://cran.r-project.org/package=fsr . Our tool provides methods for building fuzzy spatial objects as spatial plateau objects and conducting exploratory spatial data analysis by using fuzzy spatial operations.  相似文献   

20.
Geographic citizen science has much potential to assist in wildlife research and conservation, but the quality of observation data is a key concern. We examined the effects of sampling design on the quality of spatial data collected for a koala citizen science project in Australia. Data were collected from three samples—volunteers (n = 454), an Internet panel (n = 103), and landowners (n = 35)—to assess spatial data quality, a dimension of citizen science projects rarely considered. The locational accuracy of koala observations among the samples was similar when benchmarked against authoritative data (i.e., an expert‐derived koala distribution model), but there were differences in the quantity of data generated. Fewer koala location data were generated per participant by the Internet panel sample than the volunteer or landowner samples. Spatial preferences for land uses affecting koala conservation were also mapped, with landowners more likely to map locations for residential and tourism development and volunteers less likely. These spatial preferences have the potential to influence the social acceptability of future koala conservation proposals. With careful sampling design, both citizen observations and land use preferences can be included within the same project to augment scientific assessments and identify conservation opportunities and constraints.  相似文献   

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