**1. Introduction: 3D sustainable urban form**

Urban form is defined as a composite of the patterns of land use, transportation network and urban design [1]. It is also defined as the spatial pattern of the "large, inert and permanent physical objects" ([2], p. 47). Anderson et al. [3] defined urban form as the "spatial pattern of human activities". Aggregation of repetitive elements determines a form and urban form is a result of urban patterns [4]. Indeed, these urban patterns are the results of the repetition and combination of undifferentiated elements [4]. Considering the scale of analysis, Tsai [5] classified

the levels of urban form analysis into neighborhood, city and metropolitan area together with three variables of density, diversity and spatial structure. These variables for different scales of analysis may carry different meanings. Therefore, firstly, the scale of analysis needs to be determined, and then the meaning of the variable for that scale needs to be found. While plot and urban block are the terms implying local scale, urban form is used for a range of scales from local to regional (i.e. neighborhood, city and metropolitan area).

Sustainability of urban form is a crucial topic that needs to be carefully considered for future cities.1 The need of sustainable cities was recognized by the United Nations (UN) in setting up the UN Sustainable Development Goals [6], in which the 11th goal aims to "Make cities and human settlements inclusive, safe, resilient and sustainable". According to the UN, city populations are growing with about 54% of the global population,or about 3.9 billion people, now living in cities [6]. One of the issues facing future cities centers around climate change. Land use has been known as one of the major factors affecting the level of heat in urban areas at a large scale. If we think about cities in three dimensions, we see that the height and bulk of buildings are also important factors in local climate phenomena, in particular the urban heat island (UHI) effect defined by the temperature difference between urban areas and their surrounding rural areas. Building height and geometry affect the distribution patterns of shade, wind speed and wind direction. Urban canyon geometry (orientation plus aspect ratio, the ratio of average building height to street width) affects street ventilation and the dispersion of air pollution. In turn, these factors interact with the urban heat islands effect to create a unique urban microclimate.

Knowledge of three-dimensional (3D) urban growth including changes in human formed and natural objects requires accurate monitoring systems that are able to identify areas with greater changes that are unsustainable and therefore can be prioritized areas for greater attention for intervention policies and activities. In this way, the monitoring system helps to build a more resilient urban form that should maintain adequate levels of the natural environment in built-up areas.

In addition, urban vegetation cover has positive effects on microclimate since it helps to reduce carbon emissions though absorbing CO2 as well as mitigating other gaseous and particulate air pollution. Additionally, it helps to minimize soil erosion, retain soil moisture and reduce the generation of dust.

Current urban change studies focus on land use change detection occurring in decades or annually at large scales and ignore short-term changes of vegetation within built-up areas. Also, detected urban changes are generally two-dimensional; for example, rarely changes within an area of lawn or area of trees have been noticed. The differential effects of trees and grass areas on microclimate can be easily understood in terms of shading and evapotranspiration. Also in Shanahan et al. [7], the benefits of tree cover in a city in the UK one in Australia, were estimated by 'Nature Relatedness', in which tree cover varied from less than 10% to more than 60%. The Natural Relatedness scale correlates well with attitudes toward nature and distinguishes between those who are enthusiastic about nature and those who are not. The chapter demonstrates the benefits of tree cover including reduced stress and asthma and 'psychological restoration'. 'Nature dose intensity' in the form of trees taller than 2 m was assessed using airborne lidar and NDVI from Landsat 8 images [8].

This raises a critical question about how vegetation cover changes compared to 3D changes in built form in urban areas. Through exploring fine resolution 3D

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**Figure 1.**

*New Metrics for Spatial and Temporal 3D Urban Form Sustainability Assessment Using Time…*

changes within a built up area and to answer the above research question, this work reviews and discusses existing 3D metrics for defining sustainable urban form (3D SUF), proposes some new 3D metrics and develops a new approach to processing time series airborne lidar for monitoring 3D SUF, to support decision-making in favor of a more resilient and sustainable urban form for future generations.

The rapid growth of high-rise urban development has created an urgent need for new methods for characterizing the trends and patterns of these developments, including changes in time series 3D data sets. Repeated airborne lidar data coverage can provide accurate 3D data revealing changes of building heights over time. Integration of information derived from remote sensing acquisition systems with new digital technologies, such as GIS-based applications, provides a unique oppor-

tunity to the users for interactive accessibility to the magnitude of change.

**2. Developing conceptual approaches of urban growth modeling** 

*Developing conceptual approaches for studying 3D urban dynamics (adapted from Herold et al. (2005)).*

There are two major conceptual approaches at metropolitan scale for the analysis of spatial and temporal urban patterns, namely, traditional and modern perspectives. These approaches are illustrated in **Figure 1** adapted from Herold [9]. Herold explains that processes produce structures in the traditional top-down view (i.e. from process to structure), whereas two-dimensional spatial arrangements of urban elements such as open and public spaces (i.e. structures) are representative of socioeconomic activities or policies and strategic plans to achieve a certain type of urban pattern (i.e. process) in the modern bottom-up view (i.e. from structure to process). Demand for land, master plans and economic forces are major drivers

In this research, we use the advanced remote sensing technology of Light Detection and Ranging (lidar) to acquire time series airborne data to detect 3D morphological changes in inner city locations and visualize the outcomes in a GIS-based application in which the end-user can readily access information

*DOI: http://dx.doi.org/10.5772/intechopen.89617*

about these changes.

**toward 3D**

<sup>1</sup> In this chapter more or less 'sustainable' refers to the dynamic relationship between vegetation and built form in the city

*New Metrics for Spatial and Temporal 3D Urban Form Sustainability Assessment Using Time… DOI: http://dx.doi.org/10.5772/intechopen.89617*

changes within a built up area and to answer the above research question, this work reviews and discusses existing 3D metrics for defining sustainable urban form (3D SUF), proposes some new 3D metrics and develops a new approach to processing time series airborne lidar for monitoring 3D SUF, to support decision-making in favor of a more resilient and sustainable urban form for future generations.

The rapid growth of high-rise urban development has created an urgent need for new methods for characterizing the trends and patterns of these developments, including changes in time series 3D data sets. Repeated airborne lidar data coverage can provide accurate 3D data revealing changes of building heights over time. Integration of information derived from remote sensing acquisition systems with new digital technologies, such as GIS-based applications, provides a unique opportunity to the users for interactive accessibility to the magnitude of change.

In this research, we use the advanced remote sensing technology of Light Detection and Ranging (lidar) to acquire time series airborne data to detect 3D morphological changes in inner city locations and visualize the outcomes in a GIS-based application in which the end-user can readily access information about these changes.
