Remote sensing of within-class change in urban neighborhood structures Tarek Rashed * Department of Geography, University of Oklahoma, Sarkeys Energy Center, RM 670, Norman, OK 73019, USA article info Article history: Received 22 June 2007 Received in revised form 26 June 2008 Accepted 26 June 2008 Keywords: Los Angeles Urban morphology Neighborhood change Spectral mixture analysis Fuzzy logic Landscape metrics abstract Two conceptual models for urban neighborhood change and urban landscape ecology are used to devise an integrative methodology for measuring temporal changes in the urban morphology of Los Angeles, California, based on the techniques of multiple endmember spectral mixture analysis (MESMA), land- scape metrics, and fuzzy logic. To illustrate an application of the methodology, the research utilizes two Landsat Thematic Mapper images acquired in 1990 and 2000. Through a wall-to-wall exercise, the paper discusses: (1) how the spatially continuous character of the urban morphology in Los Angeles is analyzed through the use of MESMA technique to capture and quantify within-class changes in land cover at the sub-pixel level; (2) how the magnitude of land cover changes is assessed through fuzzy logic; and (3) how landscape metrics are applied to quantify patterns of change in land cover at the census tract level. The results of the case study indicate that the integration of MESMA, fuzzy logic and landscape met- rics can provide a systematic way to derive comparable measures of change in urban neighborhoods in Los Angeles. Further research is however needed to develop more rigorous methods for assessing the accuracy of land cover fractions generated by MESMA. The paper concludes with a discussion of how the proposed methodology may present a step towards a closer integration of remote sensing technology into the reformation of planning policies concerning urban sustainable development. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Motivated by a global concern for sustainability and environ- mental quality in cities, a considerable number of studies have uti- lized satellite sensor data in the analysis of urban morphological change (e.g. De Almedia et al., 2005; Herold, Goldstein, & Clarke, 2003; Mesev, 2003). Some studies focused on the physical and socioeconomic drivers of change in urban land cover and implica- tions on land use practices and resource management. Other stud- ies went beyond the characterization of change and its causes and attempted to integrate remotely sensed data with models of urban growth to project future change (Dietzel, Oguz, Hemphill, Clarke, & Gazulis, 2005). Looking at how these studies have informed and been linked to sustainability policies, one can easily observe a sole focus on the so-called ‘‘smart growth,” or ‘‘new urbanism” approach to develop- ment in developed countries. This approach directs attention to changes that occur at the urban fringe, as in the case of ‘‘edge cit- ies” in the US and decentralized suburban communities in Europe (Longley & Mesev, 2001; Pincetl, Wolch, Wilson, & Longcore, 2003). Even in the context of developing countries, where the impact of sustainable policies is less pronounced, remote sensing studies have focused mainly on the decline of agricultural land and loss of biodiversity caused by urban sprawl and informal settlements (Chen, Zheng, & Xie, 2000). A few studies have, however, directed attention to another important mode of within-class change in cit- ies associated with modifications and transformations of the phys- ical structure of neighborhood morphology (Rashed, Weeks, Stow, & Fugate, 2005). Urban neighborhoods, as Pacione (2001, p. 196) asserts, ‘‘are in a constant state of flux”. Such flux can be conceptualized as a con- tinuum in which neighborhoods at any stage can be stabilizing, improving, or declining. Bourne (1976a) suggested a model for ‘‘western” cities in which this continuum is divided into five tem- poral stages: new growth, in-filling, stability, downgrading and thinning out, and renewal. The length of each stage depends on a complex web of interactive factors and processes, demographic, social, technological, economic, cultural, political, and environ- mental, that have been a subject of a multitude of urban theories (see Galster & Mincy, 1993 for a thorough review of such theoret- ical models). Each temporal stage in Bourne’s model is further characterized with some physical transformations that may occur in urban neighborhoods (e.g. construction, densification, demoli- tion of exiting units, cluster or scattered development) (Bourne, 1976b). Physical transformations constantly occur across all the stages, including the ‘‘stability” stage, but the nature of a transfor- mation, as well as its magnitude and speed, vary by stage. The nature and patterns of physical transformations within ur- ban neighborhoods are of a major concern to sustainable develop- ment. They manifest the outcome of a range of demographic, socioeconomic, cultural, and political dynamics in cities (e.g. in 0198-9715/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.compenvurbsys.2008.06.007 * Tel.: +1 (405) 325 5104; fax: +1 (405) 325 6090. E-mail address: rashed@ou.edu Computers, Environment and Urban Systems 32 (2008) 343–354 Contents lists available at ScienceDirect Computers, Environment and Urban Systems journal homepage: www.elsevier.com/locate/compenvurbsys