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Taubenbock H.,German Aerospace Center | Standfuss I.,German Aerospace Center | Wurm M.,German Aerospace Center | Krehl A.,Research Institute for Regional and Urban Development ILS | Siedentop S.,Research Institute for Regional and Urban Development ILS
Computers, Environment and Urban Systems | Year: 2017

Polycentricity belongs to the most versatile and fuzzy concepts in urban geography. It basically points to the existence of more than one center within a conurbation. Previous studies have mostly referred to the spatial distribution of employment density for (sub-) center identification. In contrast, our study draws on large area 3D building models derived from ubiquitous remote sensing data. We use stereoscopic Cartosat-1 digital surface models in combination with building footprints. These geoinformation reflect the spatial configuration of the built dimension and allow a physical approach to the concept of polycentricity. For (sub-) center identification we thoroughly analyze conceptually different kinds of threshold approaches (global, region-specific and distance-based) applied to concentrations of urban masses. After evaluating the advantages and disadvantages of the threshold approaches applied, we combine these methods to overcome their individual shortcomings. Last but not least, we establish a framework consisting of mapping techniques and site- and non-site specific statistics to evaluate polycentricity at fine-grained spatial intra-urban scale. In general we find that urban mass concentrations are a reasonable proxy for commonly used employment density data. We address the polycentricity issue across four German city regions—Frankfurt, Cologne, Stuttgart and Munich—and we find all of them to still be morphologically dominated by their core cities. Nevertheless, our analysis reveals striking differences of the urban spatial structure highlighting a rather monocentric pattern in the Munich region on the one hand, and a polycentric-dispersed distribution of urban mass concentrations in the Stuttgart region on the other hand. © 2017 Elsevier Ltd

Krehl A.,Research Institute for Regional and Urban Development ILS | Siedentop S.,Research Institute for Regional and Urban Development ILS | Taubenbock H.,German Aerospace Center | Wurm M.,German Aerospace Center
ISPRS International Journal of Geo-Information | Year: 2016

Urban density must be considered a key concept in the description of a city's urban spatial structure. Countless studies have provided evidence of a close relationship between built density and activity densities, on the one hand, and urban environmental conditions or social practices, on the other hand. However, despite the concept's common use in urban research, urban density is a rather fuzzy and highly complex concept that is accompanied by a confusing variety of indicators and measurement approaches. To date, an internationally-accepted standard for the implementation of density indicators that permits a robust comparison of different countries, regions or cities is widely missing. This paper discusses the analytical opportunities that recent remote sensing data offer in regard to an objective and transparent measurement of built density patterns of city regions. It furthermore clarifies the interrelations between built and activity densities. We apply our approach to four German city regions to demonstrate the analytical capacity of spatially-refined density indicators for the purposes of comparative urban research at a regional scale. In so doing, we contribute to a more encompassing and robust understanding of the urban density concept when analyzing regional morphology. © 2016 by the authors.

Jain M.,University of Stuttgart | Siedentop S.,Research Institute for Regional and Urban Development ILS
Habitat International | Year: 2014

Managing growth in rapidly growing complex mega urban regions in India is a growing concern for planners and scholars. Although the government attempts to regulate the development by spatial decentralization, there are no easy solutions, resulting in undesirable growth and associated problems. However, a good mix of (fiscal and regulatory) interventions, although difficult to implement, has the potential to achieve effective urban growth, as exemplified by Tokyo in Asia and London in Europe. Examining the National Capital Region (NCR) Delhi as a case study, this study evaluated the performance of some aspects of spatial decentralization policy. The investigation identified the need to link jobs and housing, redefine the concept of greenbelt, and integrate transport and land-use planning. We recommend introducing a mix of interventions to effectuate spatial decentralization. © 2013 Elsevier Ltd.

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