A network based kernel density estimator applied to Barcelona economic activities

This paper presents a methodology to compute an innovative density indicator of spatial events. The methodology is based on a modified Kernel Density Estimator (KDE) that operates along road networks, and named Network based Kernel Density Estimator (NetKDE). In this research, retail and service economic activities are projected on the road network whose edges are weighted by a set of centrality values calculated with a Multiple Centrality Assessment (MCA). First, this paper calculate a density indicator for the point pattern analysis on human activities in a network constrained environment. Then, this indicator is modified to evaluate network performance in term of centrality. The methodology is applied to the city of Barcelona to explore the potential of the approach on more than 11,000 network edges and 166,000 economic activities

Urban monitoring using NetKDE and VGI: network based kernel density estimation on volunteered geographic information applied to Baghdad, Iraq

This paper presents a methodology for urban monitoring using volunteered geographic information (VGI) and journalism data Iraq war logs with network based kernel density estimation (NetKDE). It investigates, using spatio-temporal analysis, the evolution of urban events in Baghdad between 2004 and 2009. The extracted street network is based on the data distributed by OpenStreetMap (OSM). A total of 21,876 logged events, 66,648 network segments, 22,644 gridpoints (200m resolution grid) and 362,304 gridpoints (50m resolution grid) are used for the analysis. The methodology combines and adapts these VGI data and is mainly based on open source and/or publicly available software. It handles very large datasets with multiscale, multi-resolution and temporal perspectives. Fuzzy-set map comparison (FMC) is used to identify level of changes between each period of time. The methodology is already used in other fields of research being biology, urban planning, criminology or economic evelopment. It should help stakeholders in respective domain to analyze the evolution of network constrained events in multiple contexts. This paper is divided in three parts. Firstly, conceptual background of VGI, NetKDE and FMC is presented. Secondly, the methodology is illustrated using data Iraq war logs, OSM data and grids with two different resolutions. Thirdly, spatio-temporal analysis results are presented and discussed.Peer Reviewe

Form and urban change : an urban morphometric study of five gentrified neighbourhoods in London

Research in Urban Morphology has long been exploring the form of cities and their changes over time, especially by establishing links with the parallel dynamics of these cities’ social, economic and political environments. The capacity of an adaptable and resilient urban form for ensuring a fertile environment for economic prosperity and social cohesion is at the forefront of discussion. Gentrification has emerged in the past few decades as an important topic of research in urban sociology, geography and economy, addressing the social impact of some forms of urban evolution; to some extent, these studies emphasise the form of the environment in which gentrification takes place, however, a systematic and quantitative method for a detailed characterization of this type of urban form is still far from being achieved. With this paper, we make a first step towards the establishment of an approach based on “urban morphometrics”. To this end, we measure and compare key morphological features of five London neighbourhoods that have undergone a process of piecemeal gentrification. Findings suggest that these five case studies display similar and recognisable morphological patterns in terms of their built form, geographical location of main and local roads and physical relationships between street fronts and street types. These initial results, while not implying any causal or universal relationship between morphological and social dynamics, nevertheless contribute to; a) highlight the benefits of a rigorous quantitative approach towards interpreting urban form beyond the disciplinary boundaries of Urban Morphology and b) define the statistical recurrence of a few, specific morphological features amongst the five cases of gentrified areas in London

SUSTAINABLE LAND USE EVALUATION BASED ON PRESERVATIVE APPROACH

Determining the manner of land-use and the spatial structure of cities on the one hand, and the economic value of each piece of land on the other hand, land-use planning is always considered as the main part of urban planning. In this regard, emphasizing the efficient use of land, the sustainable development approach has presented a new perspective on urban planning and consequently on its most important pillar, i.e. land-use planning. In order to evaluate urban land-use, it has been attempted in this paper to select the most significant indicators affecting urban land-use and matching sustainable development indicators. Due to the significance of preserving ancient monuments and the surroundings as one of the main pillars of achieving sustainability, in this research, sustainability indicators have been selected emphasizing the preservation of ancient monuments and historical observance of the city of Susa as one of the historical cities of Iran. It has also been attempted to integrate these criteria with other land-use sustainability indicators. For this purpose, Kernel Density Estimation (KDE) and the AHP model have been used for providing maps displaying spatial density and combining layers as well as providing final maps respectively. Moreover, the rating of sustainability will be studied in different districts of the city of Shush so as to evaluate the status of land sustainability in different parts of the city. The results of the study show that different neighborhoods of Shush do not have the same sustainability in land-use such that neighborhoods located in the eastern half of the city, i.e. the new neighborhoods, have a higher sustainability than those of the western half. It seems that the allocation of a high percentage of these areas to arid lands and historical areas is one of the main reasons for their sustainability

Taming the road : a GIS-based visualisation and spatial analysis methodology towards retrofitting the intermediate urban mosaic

The contemporary networks of towns and cities continue to emancipate themselves by embracing ever larger territories while shaping their interstices in heterogeneous mosaics of settlements and open spaces of variable intensity. The equilibrium of the urban system depends largely on the recognition of the importance of these unavoidable settings, in which the urban form is less sustainable and lacks structure. Although there is extensive literature and debate on this environment, there are fewer instruments of analysis addressed to reading and retrofitting it. This dissertation develops a series of GIS-based spatial analysis tools based on the topology of the road network, taking as the basic component the segment between intersections weighted by the portion of land it supports. In this way, the relationship between settlement/activity spreading and road network is modelled. These precepts underpin the proposed measures which have been named ¿upstream and downstream visualisation.¿ The former accounts for neighbourhood relationships, prioritising those places which have high concentrations of activity in their proximities, even if their spatial configuration is scattered. This reading is combined with the use of complementary centrality measures. The latter makes it possible to load the areas of activity onto the roads which support them. The Vallès Oriental district, included in the Barcelona Metropolitan Region, is taken as a case study. The results reveal the intensities of the groupings of settlements and their relative weight in the territory, and at the same time they define the regional vertebrating skeleton on which the gateways of access to the activity are manifested. They also reveal the relational structure of proximity of the city-territory. Moreover, their endogenic potentials are identified, converted into vocations at the moment of directing strategies of urban transformation. A selective activation of these aptitudes is suggested for approaching the retrofitting of the intermediate urban mosaic.Les xarxes de ciutats contemporànies continuen emancipant-se abraçant territoris cada vegada més amplis mentre transformen els seus intersticis en mosaics heterogenis d'assentaments i espais oberts d'intensitat variable. L'equilibri del sistema urbà depèn en bona mesura del reconeixement de la importància d'aquest àmbits inevitables, en què la forma urbana és menys sostenible i mancada d'estructura. Si bé existeix una àmplia literatura i debat sobre aquest medi en qüestió, existeixen menys instruments d'anàlisi orientats a la seva lectura i reconstrucció. Aquesta tesi doctoral desenvolupa un conjunt d'eines d'anàlisi espacial per entorns SIG basades en la topologia de la xarxa viària, prenent com a component bàsic el segment entre interseccions conjuntament amb la porció de sòl que suporta. D'aquesta manera es modela la relació entre el desplegament de l'activitat/assentaments i la xarxa viària. Amb aquests preceptes es proposen les mesures que s'han anomenat upstream i downstream visualization. La primera dóna compte de les relacions de veïnatge, premiant aquells indrets que tenen concentracions elevades d'activitat en les seves proximitats tot i que la seva configuració espacial sigui fragmentada. Aquest lectura es combina amb l'ús de mesures de centralitat complementàries. La segona permet carregar les conques d'activitat sobre les carreteres que les suporten. La comarca del Vallès Oriental, inclosa a la Regió Metropolitana de Barcelona, es pres com a cas d'estudi. Els resultats evidencien les intensitats dels agrupaments d'assentaments i el seu pes relatiu en el territori i, alhora, defineixen l'esquelet vertebrador regional sobre el qual es manifesten les portes d'accés a l'activitat. Es posa de manifest l'estructura relacional de proximitat de la ciutat-territori. Addicionalment, s'identifiquen els seus potencials endògens que es tradueixen amb vocacions a l'hora de endegar estratègies de transformació urbana. Se suggereix una activació selectiva d'aquestes aptituds per a encarar la reconstrucció del mosaic urbà intermedi

A Network Based Kernel Density Estimator Applied to Barcelona Economic Activities

This paper presents a methodology to compute an innovative density indicator of spatial events. The methodology is based on a modified Kernel Density Estimator (KDE) that operates along road networks, and named Network based Kernel Density Estimator (NetKDE). In this research, retail and service economic activities are projected on the road network whose edges are weighted by a set of centrality values calculated with a Multiple Centrality Assessment (MCA). First, this paper calculate a density indicator for the point pattern analysis on human activities in a network constrained environment. Then, this indicator is modified to evaluate network performance in term of centrality. The methodology is applied to the city of Barcelona to explore the potential of the approach on more than 11,000 network edges and 166,000 economic activities

Integration of Urban Structures in Point Process Analysis

Traditionally, spatial analysis of point pattern has been mostly focused on Euclidean space. As many human related phenomena take place on a network, the assumption of a continuous isotropic space fails to describe events which actually occur on a one-dimensional subset of this space. Thus, recently, researchers have begun integrating network structure constraints to study point patterns. The focus of this report is primarily aimed at the integration of the network structure constraints in studying the first order property of point processes with Kernel Density Estimation (KDE). Two different approaches and the computational methods used to calculate network based kernel density estimation (NetKDE) are described, and are then compared to each other as well as to KDE. An original approach which aim is to replace the conventional search area in flat disk through Euclidean space is introduced. In urban context, polygons of various shapes can be generated and used over the network as an approximation of the potential accessible area for a given distance. As a first case-study, network based density values for various types of economic activities are generated for each building in Geneva. The integration of urban structures in the characterization of neighborhood attributes is an innovative approach which possesses many advantages. A classification based on the attributes generated with this method is performed, and a detailed analysis of the results is carried out. In a second case-study in urban environment, time is considered as an additional dimension in kernel density estimates. A three dimensional KDE approach is used in an attempt to monitor the risk associated with the explosions of improvised explosive devices (IED) in Baghdad through space and time. An animation of the simulations is presented as a visualization technique to detect sensitive areas

Geomasking: Análisis y comparativa de algoritmos para perturbaciones de puntos.

Se ha propuesto como objetivo, partiendo de una investigación previa teórica, detectar la existencia de una relación directa y/o indirecta entre el grado de enmascaramiento de datos geográficos y los resultados obtenidos bajo bajo métodos de análisis como Kernel Density Estimation (KDE).The objective, starting from a theoretical previous investigation, is to detect the existence of a direct and / or indirect relationship between the degree of geomasking and the results obtained under analysis methods such as Kernel Density Estimation (KDE)