Emerging paradigm shift in urban indicators: Integration of the vertical dimension.

Since new urbanism strategies encourage higher density and compact city development, it is expected that the height of urban environments will increase in the next few years as a remedy for many urban problems such as urban sprawl, cost of living, and detrimental environmental impacts of horizontal development of cities. Therefore, urban designers and planners should consider the third dimension of cities according to the vertical growth paradigm that is inherently a three-dimensional (3D) socioeconomic and environmental process. While a large body of literature is focusing on horizontal or two-dimensional (2D) urban indicators, it still lacks more research to compare 2D and 3D urban indicators. In this study, urban environment quality indicators, as a prominent example of urban indicators, were measured in two and three dimensions in the central business district of Urmia in Iran. Also, a Pearson's correlation analysis was performed to find a pairwise relationship between indicators. The results of the correlation analysis revealed that most 3D indicators have no significant linear relationship with other indicators, so predicting 3D indicator values based on other indicators is a difficult or even impossible task. Comparing 2D indicators with 3D ones shows that approximately 30 percent of the study area has a different urban environmental quality if it integrates the vertical dimension with 2D indicators. In addition, measuring and modelling 3D indicators provide better locational information on urban conditions and the life of citizens than traditional 2D urban indicators. This study recommends planning for the expansion of 3D information and associated tools that lead to deeper analytical insights into 3D Urban Environmental Quality assessment.