| 1. |
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| 2. |
- Bin, Jiang, 1965-, et al.
(författare)
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Automatic generation of the axial lines of urban environments to capture what we perceive
- 2010
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 24:4, s. 545-558
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Tidskriftsartikel (refereegranskat)abstract
- Based on the concepts of isovists and medial axes, we developed a set of algorithms that can automatically generate axial lines for representing individual linearly stretched parts of open space of an urban environment. Open space is the space between buildings, where people can freely move around. The generation of the axial lines has been a key aspect of space syntax research, conventionally relying on hand-drawn axial lines of an urban environment, often called axial map, for urban morphological analysis. Although various attempts have been made towards an automatic solution, few of them can produce the axial map that consists of the least number of longest visibility lines, and none of them really works for different urban environments. Our algorithms provide a better solution than existing ones. Throughout this paper, we have also argued and demonstrated that the axial lines constitute a true skeleton, superior to medial axes, in capturing what we perceive about the urban environment.
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| 3. |
- Bin, Jiang, 1965-, et al.
(författare)
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Computing the fewest-turn map directions based on the connectivity of natural roads
- 2011
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:7, s. 1069-1082
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we introduced a novel approach to computing the fewest-turn map directions or routes based on the concept of natural roads. Natural roads are joined road segments that perceptually constitute good continuity. This approach relies on the connectivity of natural roads rather than that of road segments for computing routes or map directions. Because of this, the derived routes posses the fewest turns. However, what we intend to achieve are the routes that not only possess the fewest turns, but are also as short as possible. This kind of map direction is more effective and favorable by people, because they bear less cognitive burden. Furthermore, the computation of the routes is more efficient, since it is based on the graph encoding the connectivity of roads, which is significantly smaller than the graph of road segments. We made experiments applied to eight urban street networks from North America and Europe in order to illustrate the above stated advantages. The experimental results indicate that the fewest-turn routes posses fewer turns and shorter distances than the simplest paths and the routes provided by Google Maps. For example, the fewest-turn-and-shortest routes are on average 15% shorter than the routes suggested by Google Maps, while the number of turns is just half as much. This approach is a key technology behind FromToMap.org - a web mapping service using openstreetmap data.
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| 4. |
- Friberg, Febe, 1950, et al.
(författare)
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Nurses’ patient-education work : conditional factors - an integrative review.
- 2012
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Ingår i: Journal of Nursing Management. - : Wiley-Blackwell Publishing Ltd.. - 0966-0429 .- 1365-2834 .- 1365-263X. ; 20:2, s. 170-186
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The aim of this review was to identify conditional factors for nurses' patient-education work and to identify foundational aspects of significance when designing studies on this patient-education work. BACKGROUND: A few reviews of nurses patient education work exist, published up to 30 years ago, spawning interest in performing a review of more recent studies. EVALUATION: A search of CINAHL, MEDLINE and ERIC was made for articles dating from 1998 to 2011. Thirty-two articles were selected and an integrative review was performed. KEY ISSUES: Conditional factors were identified and beliefs and knowledge, environment, organization, interdisciplinary cooperation, collegial teamwork and patient education activities. A model was developed to describe foundational aspects of significance when designing studies. CONCLUSIONS: The conditional factors are to be seen as either enabling or hindering the accomplishment of evidence-based patient education and the level of person centredness, patient safe care and ethics - something that has to be considered when designing studies. IMPLICATIONS FOR NURSING MANAGEMENT: More detailed studies are required to clarify the nature of patient education work and to create realistic conditions that enable the role to be fulfilled in everyday work. Such knowledge is of significance for nursing management in developing supportive activities for nurses.
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| 5. |
- Huang, Wei, et al.
(författare)
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Predicting human mobility with activity changes
- 2015
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 29:9, s. 1569-1587
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Tidskriftsartikel (refereegranskat)abstract
- Human mobility patterns can provide valuable information in understanding the impact of human behavioral regularities in urban systems, usually with a specific focus on traffic prediction, public health or urban planning. While existing studies on human movement have placed huge emphasis on spatial location to predict where people go next, the time dimension component is usually being treated with oversimplification or even being neglected. Time dimension is crucial to understanding and detecting human activity changes, which play a negative role in prediction and thus may affect the predictive accuracy. This study aims to predict human movement from a spatio-temporal perspective by taking into account the impact of activity changes. We analyze and define changes of human activity and propose an algorithm to detect such changes, based on which a Markov chain model is used to predict human movement. The Microsoft GeoLife dataset is used to test our methodology, and the data of two selected users is used to evaluate the performance of the prediction. We compare the predictive accuracy (R-2) derived from the data with and without implementing the activity change detection. The results show that the R-2 is improved from 0.295 to 0.762 for the user with obvious activity changes and from 0.965 to 0.971 for the user without obvious activity changes. The method proposed by this study improves the accuracy in analyzing and predicting human movement and lays the foundation for related urban studies.
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| 6. |
- Jiang, Bin, 1965-, et al.
(författare)
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Agent-based simulation of human movement shaped by the underlying street structure
- 2011
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:1, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- Relying on random and purposive moving agents, we simulated human movement in large street networks. We found that aggregate flow, assigned to individual streets, is mainly shaped by the underlying street structure, and that human moving behavior (either random or purposive) has little effect on the aggregate flow. This finding implies that given a street network, the movement patterns generated by purposive walkers (mostly human beings) and by random walkers are the same. Based on the simulation and correlation analysis, we further found that the closeness centrality is not a good indicator for human movement, in contrast to a long-standing view held by space syntax researchers. Instead we suggest that Google's PageRank and its modified version (weighted PageRank), betweenness and degree centralities are all better indicators for predicting aggregate flow.
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| 7. |
- Jiang, Bin, 1965-, et al.
(författare)
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Geographic space as a living structure for predicting human activities using big data
- 2019
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 33:4, s. 764-779
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Tidskriftsartikel (refereegranskat)abstract
- Inspired by Christopher Alexander's conception of the world - space is not lifeless or neutral, but a living structure involving far more small things than large ones - a topological representation has been previously developed to characterize the living structure or the wholeness of geographic space. This paper further develops the topological representation and living structure for predicting human activities in geographic space. Based on millions of street nodes of the United Kingdom extracted from OpenStreetMap, we established living structures at different levels of scale in a nested manner. We found that tweet locations at different levels of scale, such as country and city, can be well predicted by the underlying living structure. The high predictability demonstrates that the living structure and the topological representation are efficient and effective for better understanding geographic forms. Based on this major finding, we argue that the topological representation is a truly multiscale representation, and point out that existing geographic representations are essentially single scale, so they bear many scale problems such as modifiable areal unit problem, the conundrum of length and the ecological fallacy. We further discuss on why the living structure is an efficient and effective instrument for structuring geospatial big data, and why Alexander's organic worldview constitutes the third view of space.
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| 8. |
- Jiang, Bin
(författare)
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Making GIScience research more open access
- 2011
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:8, s. 1217-1220
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 9. |
- Jiang, Bin, et al.
(författare)
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Scaling of geographic space from the perspective of city and field blocks and using volunteered geographic information
- 2012
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 26:2, s. 215-229
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Tidskriftsartikel (refereegranskat)abstract
- Scaling of geographic space refers to the fact that for a large geographic area its small constituents or units are much more common than the large ones. This paper develops a novel perspective to the scaling of geographic space using large street networks involving both cities and countryside. Given a street network of an entire country, we decompose the street network into individual blocks, each of which forms a minimum ring or cycle such as city blocks and field blocks. The block sizes demonstrate the scaling property, i.e., far more small blocks than large ones. Interestingly, we find that the mean of all the block sizes can easily separate between small and large blocks- a high percentage (e.g., 90%) of smaller ones and a low percentage (e.g., 10%) of larger ones. Based on this regularity, termed as the head/tail division rule, we propose an approach to delineating city boundaries by grouping the smaller blocks. The extracted city sizes for the three largest European countries (France, Germany and UK) exhibit power law distributions. We further define the concept of border number as a topological distance of a block far from the outmost border to map the center(s) of the country and the city. We draw an analogy between a country and a city (or geographic space in general) with a complex organism like the human body or the human brain to further elaborate on the power of this block perspective in reflecting the structure or patterns of geographic space.
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| 10. |
- Jiang, Bin
(författare)
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The fractal nature of maps and mapping
- 2015
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 29:1, s. 159-174
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Tidskriftsartikel (refereegranskat)abstract
- A fractal can be simply understood as a set or pattern in which there are far more small things than large ones, for example, far more small geographic features than large ones on the earth surface, or far more large-scale maps than small-scale maps for a geographic region. This article attempts to argue and provide evidence for the fractal nature of maps and mapping. It is the underlying fractal structure of geographic features, either natural or man-made, that make reality mappable, large-scale maps generalizable, and cities imageable. The fractal nature is also what underlies the beauty of maps. After introducing some key fractal concepts such as recursion, self-similarity, scaling ratio, and scaling exponent, this article demonstrates that fractal thought is rooted in long-standing map-making practices such as series maps subdivision, visual hierarchy, and Töpfer's radical law. Drawing on previous studies on head/tail breaks, mapping can be considered a head/tail breaks process; that is to divide things around an average, according to their geometric, topological and/or semantic properties, into the head (for those above the average) and the tail (for those below the average), and recursively continue the dividing process for the head for map generalization, statistical mapping, and cognitive mapping. Given the fractal nature of maps and mapping, cartography should be considered a perfect combination of science and art, and scaling must be formulated as a law of cartography or that of geography in general.
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| 11. |
- Jiang, Bin
(författare)
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Wholeness as a hierarchical graph to capture the nature of space
- 2015
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 29:9, s. 1632-1648
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Tidskriftsartikel (refereegranskat)abstract
- According to Christopher Alexander’s theory of centers, a whole comprises numerous, recursively defined centers for things or spaces surrounding us. Wholeness is a type of global structure or life-giving order emerging from the whole as a field of the centers. The wholeness is an essential part of any complex system and exists, to some degree or other, in spaces. This paper defines wholeness as a hierarchical graph, in which individual centers are represented as the nodes and their relationships as the directed links. The hierarchical graph gets its name from the inherent scaling hierarchy revealed by the head/tail breaks, which is a classification scheme and visualization tool for data with a heavy-tailed distribution. We suggest that (1) the degrees of wholeness for individual centers should be measured by PageRank (PR) scores based on the notion that high-degree-of-life centers are those to which many high-degree-of-life centers point, and (2) that the hierarchical levels, or the ht-index of the PR scores induced by the head/tail breaks, can characterize the degree of wholeness for the whole: the higher the ht-index, the more life or wholeness in the whole. Three case studies applied to the Alhambra building complex and the street networks of Manhattan and Sweden illustrate that the defined wholeness captures fairly well human intuitions on the degree of life for the geographic spaces. We further suggest that the mathematical model of wholeness be an important model of geographic representation, because it is topological oriented, which enables us to see the underlying scaling structure. The model can guide geodesign, which should be considered as the wholeness-extending transformations that are essentially like the unfolding processes of seeds or embryos, for creating built and natural environments of beauty or with a high degree of wholeness.
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| 12. |
- Jiang, Bin, et al.
(författare)
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Zipf’s law for all the natural cities around the world
- 2015
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 29:3, s. 498-522
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Tidskriftsartikel (refereegranskat)abstract
- Two fundamental issues surrounding research on Zipf’s law regarding city sizes are whether and why this law holds. This paper does not deal with the latter issue with respect to why, and instead investigates whether Zipf’s law holds in a global setting, thus involving all cities around the world. Unlike previous studies, which have mainly relied on conventional census data such as populations and census-bureau-imposed definitions of cities, we adopt naturally (in terms of data speak for itself) delineated cities, or natural cities, to be more precise, in order to examine Zipf’s law. We find that Zipf’s law holds remarkably well for all natural cities at the global level, and it remains almost valid at the continental level except for Africa at certain time instants. We further examine the law at the country level, and note that Zipf’s law is violated from country to country or from time to time. This violation is mainly due to our limitations; we are limited to individual countries, or to a static view on city-size distributions. The central argument of this paper is that Zipf’s law is universal, and we therefore must use the correct scope in order to observe it. We further find Zipf’s law applied to city numbers; the number of cities in the largest country is twice as many as that in the second largest country, three times as many as that in the third largest country, and so on. These findings have profound implications for big data and the science of cities.
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| 13. |
- Jiang, Bin, 1965-, et al.
(författare)
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Zipf’s Law for All the Natural Cities in the United States : A Geospatial Perspective
- 2011
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:8 (Special issue), s. 1269-1281
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Tidskriftsartikel (refereegranskat)abstract
- This article provides a new geospatial perspective on whether or not Zipf's law holds for all cities or for the largest cities in the United States using a massive dataset and its computing. A major problem around this issue is how to define cities or city boundaries. Most of the investigations of Zipf's law rely on the demarcations of cities imposed by census data, for example, metropolitan areas and census-designated places. These demarcations or definitions (of cities) are criticized for being subjective or even arbitrary. Alternative solutions to defining cities are suggested, but they still rely on census data for their definitions. In this article we demarcate urban agglomerations by clustering street nodes (including intersections and ends), forming what we call natural cities. Based on the demarcation, we found that Zipf's law holds remarkably well for all the natural cities (over 2-4 million in total) across the United States. There is little sensitivity for the holding with respect to the clustering resolution used for demarcating the natural cities. This is a big contrast to urban areas, as defined in the census data, which do not hold stable for Zipf's law.
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| 14. |
- Kashian, Alireza, et al.
(författare)
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Automatic analysis of positional plausibility for points of interest in OpenStreetMap using coexistence patterns
- 2019
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 33:7, s. 1420-1443
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Tidskriftsartikel (refereegranskat)abstract
- In the past decade, Volunteered Geographic Information (VGI) has emerged as a new source of geographic information, making it a cheap and universal competitor to existing authoritative data sources. The growing popularity of VGI platforms, such as OpenStreetMap (OSM), would trigger malicious activities such as vandalism or spam. Similarly, wrong entries by unexperienced contributors adds to the complexities and directly impact the reliability of such databases. While there are some existing methods and tools for monitoring OSM data quality, there is still a lack of advanced mechanisms for automatic validation. This paper presents a new recommender tool which evaluates the positional plausibility of incoming POI registrations in OSM by generating near real-time validation scores. Similar to machine learning techniques, the tool discovers, stores and reapplies binary distance-based coexistence patterns between one specific POI and its surrounding objects. To clarify the idea, basic concepts about analysing coexistence patterns including design methodology and algorithms are covered in this context. Furthermore, the results of two case studies are presented to demonstrate the analytical power and reliability of the proposed technique. The encouraging results of this new recommendation tool elevates the need for developing reliable quality assurance systems in OSM and other VGI projects.
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| 15. |
- Lim, Nancy Joy, 1980-, et al.
(författare)
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Visualisation and evaluation of flood uncertainties based on ensemble modelling
- 2016
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 30:2, s. 240-262
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluates how users incorporate visualisation of flood uncertainty information in decision-making. An experiment was conducted where participants were given the task to decide building locations, taking into account homeowners’ preferences as well as dilemmas imposed by flood risks at the site. Two general types of visualisations for presenting uncertainties from ensemble modelling were evaluated: (1) uncertainty maps, which used aggregated ensemble results; and (2) performance bars showing all individual simulation outputs from the ensemble. Both were supplemented with either two-dimensional (2D) or three-dimensional (3D) contextual information, to give an overview of the area.The results showed that the type of uncertainty visualisation was highly influential on users’ decisions, whereas the representation of the contextual information (2D or 3D) was not. Visualisation with performance bars was more intuitive and effective for the task performed than the uncertainty map. It clearly affected users’ decisions in avoiding certain-to-be-flooded areas. Patterns to which the distances were decided from the homeowners’ preferred positions and the uncertainties were similar, when the 2D and 3D map models were used side by side with the uncertainty map. On the other hand, contextual information affected the time to solve the task. With the 3D map, it took the participants longer time to decide the locations, compared with the other combinations using the 2D model.Designing the visualisation so as to provide more detailed information made respondents avoid dangerous decisions. This has also led to less variation in their overall responses.
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| 16. |
- Lindsay, John B., et al.
(författare)
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Measuring the significance of a divide to local drainage patterns
- 2013
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 27:7, s. 1453-1468
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a framework for estimating a new topographic attribute derived from digital elevation models (DEMs) called maximum branch length (B-max). Branch length is defined as the distance travelled along a flow path initiated at one grid cell to the confluence with the flow path passing through a second cell. B-max is the longest branch length measured for a grid cell and its eight neighbours. The index provides a physically meaningful method for assessing the relative significance of drainage divides to the dispersion of materials and energy across a landscape, that is, it is a measure of divide size'. B-max is particularly useful for studying divide network structure, for mapping drainage divides, and in landform classification applications. Sensitivity analyses were performed to evaluate the robustness of estimates of B-max to the algorithm used to estimate flow lengths and the prevalence of edge effects resulting from inadequate DEM extent. The findings suggest that the index is insensitive to the specific flow algorithm used but that edge effects can result in significant underestimation along major divides. Edge contamination can, however, be avoided by using an appropriately extensive DEM.
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| 17. |
- Lyon, Steve, et al.
(författare)
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Using landscape characteristics to define an adjusted distance metric for improving kriging interpolations
- 2010
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 24:5, s. 723-740
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Tidskriftsartikel (refereegranskat)abstract
- Interpolation of point measurements using geostatistical techniques such as kriging can be used to estimate values at non-sampled locations in space. Traditional geostatistics are based on the spatial autocorrelation concept that nearby things are more related than distant things. In this study, additional information was used to modify the traditional Euclidean concept of distance into an adjusted distance metric that incorporates similarity in terms of quantifiable landscape characteristics such as topography or land use. This new approach was tested by interpolating soil moisture content, pH and carbon-tonitrogen (C:N) ratio measured in both the mineral and the organic soil layers at a field site in central Sweden. Semivariograms were created using both the traditional distance metrics and the proposed adjusted distance metrics to carry out ordinary kriging (OK) interpolations between sampling points. In addition, kriging with external drift (KED) was used to interpolate soil properties to evaluate the ability of the adjusted distance metric to incorporate secondary data into interpolations. The new adjusted distance metric typically lowered the nugget associated with the semivariogram, thereby better representing small-scale variability in the measured data compared to semivariograms based on the traditional distance metric. The pattern of the resulting kriging interpolations using KED and OK based on the adjusted distance metric were similar because they represented secondary data and, thus, enhanced small-scale variability compared to traditional distance OK. This created interpolations that agreed better with what is expected for the real-world spatial variation of the measured properties. Based on cross-validation error, OK interpolations using the adjusted distance metric better fit observed data than either OK interpolations using traditional distance or KED. © 2010 Taylor & Francis.
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| 18. |
- Milutinovic, Goran, et al.
(författare)
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The impact of interactive visualization on trade-off-based geospatial decision-making
- 2019
-
Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 33:10, s. 2094-2123
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Tidskriftsartikel (refereegranskat)abstract
- In a previous work we developed GISwaps, a novel method for geospatial decision-making based on Even Swaps. In this paper, we present the results of an evaluation of a visualization framework integrated with this method, implemented within a decision support system. This evaluation is based on two different studies. In the quantitative study, 15 student participants used GISwaps with no visual features, and 15 participants used GISwaps with the integrated visual framework, as the tool in a solar farm site location case study. The results of the quantitative evaluation show positive impact of the visualization in terms of increased coherency in trade-offs. The results also show a statistically significant difference in average trade-off values between the groups, with users from the non-visual group setting on average 20% higher trade-off values compared with the users in the visual group. In the qualitative study, we had one expert in GIS, two experts in decision-making and two experts in solar energy as a focus user group. Data in this study were obtained by observations and semi-structured interviews with the participants. The impact of the visualization framework was assessed positively by all participants in the expert group.
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| 19. |
- Murekatete, Rachel Mundeli, 1981-, et al.
(författare)
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A spatial and statistical analysis of the impact of transformation of raster cost surfaces on the variation of least-cost paths
- 2018
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 32:11, s. 2169-2188
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Tidskriftsartikel (refereegranskat)abstract
- Planners who are involved in locational decision-making often useraster-based geographic information systems to quantify the valueof land in terms of suitability or cost for a certain use. From acomputational point of view, this process can be seen as a transformationof one or more sets of values associated with a grid ofcells into another set of such values through a function reflectingone or more criteria. While it is generally anticipated that differenttransformations lead to different ‘best’ locations, little has beenknown on how such differences arise (or do not arise). The paperattempts to answer this question in the context of path planningthrough a series of computational experiments using a number ofrandom landscape grids with a variety of spatial and nonspatialstructures. In the experiments, we generated least-cost paths on anumber of cost grids transformed from the landscape grids usinga variety of transformation parameters and analyzed the locationsand (weighted) lengths of those paths. Results show that the samepair of terminal cells may well be connected by different least-costpaths on different cost grids though derived from the same landscapegrid and that the variation among those paths is affected byhow given values are distributed in the landscape grid as well asby how derived values are distributed in the cost grids. Mostsignificantly, the variation tends to be smaller when the landscapegrid contains more distinct patches of cells potentially attractingor distracting cost-saving passage or when the cost grid contains asmaller number of low-cost cells.
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| 20. |
- Prelipcean, Adrian Corneliu, 1989-, et al.
(författare)
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Measures of transport mode segmentation of trajectories
- 2016
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 30:9, s. 1763-1784
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Tidskriftsartikel (refereegranskat)abstract
- Rooted in the philosophy of point- and segment-based approaches for transportation mode segmentation of trajectories, the measures that researchers have adopted to evaluate the quality of the results (1) are incomparable across approaches, hence slowing the progress in the field and (2) do not provide insight about the quality of the continuous transportation mode segmentation. To address these problems, this paper proposes new error measures that can be applied to measure how well a continuous transportation mode segmentation model performs. The error measures introduced are based on aligning multiple inferred continuous intervals to ground truth intervals, and measure the cardinality of the alignment and the spatial and temporal discrepancy between the corresponding aligned segments. The utility of this new way of computing errors is shown by evaluating the segmentation of three generic transportation mode segmentation approaches (implicit, explicit–holistic, and explicit–consensus-based transport mode segmentation), which can be implemented in a thick client architecture. Empirical evaluations on a large real-word data set reveal the superiority of explicit–consensus-based transport mode segmentation, which can be attributed to the explicit modeling of segments and transitions, which allows for a meaningful decomposition of the complex learning task.
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| 21. |
- Rui, Yikang, et al.
(författare)
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Exploring the relationship between street centrality and land use in Stockholm
- 2014
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 28:7, s. 1425-1438
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the relationship between different street centralities and land-use types in Stockholm. Major centrality measures of closeness, betweenness, and straightness are calculated at both global and local levels in both the primary and dual representations of the urban street network. Adaptive kernel density estimation is adopted to transform all unevenly distributed datasets to one continuous raster framework for further analysis. After computing statistical and spatial distribution of each centrality and land-use density map, we find that the density of each street centrality is highly correlated with one type of land use. Results imply that various centralities representing street properties from different aspects can capture the land development patterns of different land-use types by reflecting human activities, and are consequently important indicators to describe urban structure.
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| 22. |
- Seipel, Stefan, et al.
(författare)
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Color map design for visualization in flood risk assessment
- 2017
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 31:11, s. 2286-2309
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Tidskriftsartikel (refereegranskat)abstract
- Visualizations of flood maps from simulation models are widely used for assessing the likelihood of flood hazards in spatial planning. The choice of a suitable type of visualization as well as efficient color maps is critical to avoid errors or bias when interpreting the data. Based on a review of previous flood uncertainty visualization techniques, this paper identifies areas of improvements and suggests criteria for the design of a task-specific color scale in flood map visualization. We contribute a novel color map design for visualizing probabilities and uncertainties from flood simulation ensembles. A user study encompassing 83 participants was carried out to evaluate the effects of this new color map on user’s decisions in a spatial planning task. We found that the type of visualization makes a difference when it comes to identification of non-hazardous sites in the flood risk map and when accepting risks in more uncertain areas. In comparison with two other existing visualization techniques, we observed that the new design was superior both in terms of task compliance and efficiency. In regions with uncertain flood statuses, users were biased toward accepting less risky locations with our new color map design.
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| 23. |
- Shirabe, Takeshi, 1971-
(författare)
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A heuristic for the maximum value region problem in raster space
- 2011
-
Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:7, s. 1097-1116
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Tidskriftsartikel (refereegranskat)abstract
- From a single-attribute raster layer in which each cell is assigned a numerical value, a connected set of a specified number of cells that has the maximum (or minimum) total value is selected. This is a highly common decision problem in the context of raster-based geographic information systems (GIS) and seems general enough to deserve inclusion in the standard functionality of such systems. Yet it is a computationally difficult optimization problem, for which no efficient exact solution method has been found. This article presents a new dynamic programming-based heuristic method for the problem. Its performance is tested with randomly generated raster layers with various degrees of spatial autocorrelation. Results suggest that the proposed heuristic is a promising alternative to the existing integer programming-based exact method, as it can handle significantly larger raster data with fair accuracy.
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| 24. |
- Shirabe, Takeshi
(författare)
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A method for finding a least-cost wide path in raster space
- 2016
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 30:8, s. 1469-1485
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Tidskriftsartikel (refereegranskat)abstract
- Given a grid of cells each having an associated cost value, a raster version of the least-cost path problem seeks a sequence of cells connecting two specified cells such that its total accumulated cost is minimized. Identifying least-cost paths is one of the most basic functions of raster-based geographic information systems. Existing algorithms are useful if the path width is assumed to be zero or negligible compared to the cell size. This assumption, however, may not be valid in many real-world applications ranging from wildlife corridor planning to highway alignment. This paper presents a method to solve a raster-based least-cost path problem whose solution is a path having a specified width in terms of Euclidean distance (rather than by number of cells). Assuming that all cell values are positive, it does so by transforming the given grid into a graph such that each node represents a neighborhood of a certain form determined by the specified path width, and each arc represents a possible transition from one neighborhood to another. An existing shortest path algorithm is then applied to the graph. This method is highly efficient, as the number of nodes in the transformed graph is not more than the number of cells in the given grid and decreases with the specified path width. However, a shortcoming of this method is the possibility of generating a self-intersecting path which occurs only when the given grid has an extremely skewed distribution of cost values.
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| 25. |
- Shirabe, Takeshi
(författare)
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A path that buys time to decide where to go
- 2014
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Ingår i: International Journal of Geographical Information Science. - : Informa UK Limited. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 28:2, s. 314-325
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the problem of planning a path in a circumstance where its origin is given, but its destination is not specified and is to be selected from among a set of candidate destinations during a trip. A situation like this may be experienced by a group of people who have different preferred destinations, as well as by an individual who is simply indecisive about where to go. To resolve such an uncertainty, one may stay at the origin until he decides on a destination, or choose to proceed on some path that does not overly deviate from a shortest path, whichever destination is eventually chosen, and make a decision on the way. The latter action is sensible when the risk of traveling longer is outweighed by the benefit of buying more time for a better destination decision. The problem of finding such a time-buying path is formulated and a simple algorithm is developed for its solution. Some extensions and applications are also discussed.
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