Comparative study of urban skyline using 3D GIS analysis, Case study: Valiasr and Rushdieh towns in Tabriz

Various physical, semantic and functional factors in the role of the city as a bed to meet the needs and a container for the activities and behaviors of residents are effective, among which the structure and visual values ​​of the environment play an important role in improving the quality of urban space (Hosseini and Et al., 1390: 84). Among these, one of the urban elements that can play an important role in promoting the quality and visual values ​​of the environment and the appearance of the city is the sky line.  The skyline is one of the most influential factors in arranging urban spaces and planning appropriate urban environments, etc.  A factor that is rarely seen in metropolitan areas today.  It seems that in order to have a diverse and at the same time harmonious urban skyline, in the first place, it is necessary to reconnect the fields of philosophy, art and daily life, which are free from the abstract and abstract view of experts.  The development of interdisciplinary professions such as GIS, architecture and urban design is one of the measures in this direction that can have a different and more accurate view of the urban skyline.  Therefore, the need for advanced geographical models for spatial three-dimensionalization and decision-making and forecasting goals in urban planning and design, especially in the case of vertical evaluation and development, is very clear and necessary.  The advantages of using three-dimensional GIS models can be high potential in urban evaluation and analysis in various dimensions of urban aesthetics and high technology in the field of spatial analysis, the ability to test urban proposals and the power of semantic and topological storage.  Mentioned above.  Therefore, the use of these softwares to analyze urban issues is very important and increases the accuracy of urban planners and managers.  For this purpose, the present study seeks to investigate the status of the urban skyline in the study areas and based on this, the importance of the perceptual and managerial dimension of the issue is analyzed using new methods and techniques.

 The analytical approach of the research is physical and the method used in this research is three-dimensional vision analysis.  Also, Arc GIS software has been used for easy preparation of the environment in 3D to perform the required analyzes.  The data set used includes: digital model data of elevation, surface and floor layers of urban blocks.

   In the present study, the concept of skyline was analyzed using three-dimensional GIS analysis in areas of urban areas 1 and 5 located in the east and northeast of Tabriz.  Areas of interest include Valiasr town and Rushdieh town.  So far, many different methods have been proposed to display and analyze the skyline.  Some of these methods were reviewed in the research background and their strengths and weaknesses were identified.  But the purpose of this article was to investigate the capabilities of 3D analysis and modeling through the development of 3D GIS in skyline display and analysis.  Evaluating the results obtained in this research and comparing it with the results of studies in this field shows that three-dimensional analysis of GIS and 3D GIS development in comparison with other methods, provided there is accurate and comprehensive information, has high efficiency and capability.  The research hypothesis is confirmed.

The skyline is important both in terms of urban architecture and in terms of urban planners and designers; Although these specialties are different in terms of information extraction methods, methods and analytical contexts, but they are quite similar in terms of results.  In general, it can be said that the skyline is one of the analyzes that are analyzed and evaluated in different software environments such as Arc GIS and in different fields.But the results of this study proved in another way that the three-dimensional GIS environment provides an opportunity to easily view and analyze the level of impact, effectiveness, volume, dimensions and angles of the skyline; This software also has high analytical power.  While the analysis of the sky line in a two-dimensional environment gives a graphical and dimensionless result, percentage and frequency.  But the most important difference and the ability to use 3D GIS analysis is that it provides a platform where even people with little knowledge of urban views can easily see the results and make decisions based on it.  Also, the capabilities and capabilities of GIS in the field of various valuations and combined analyzes of vector and raster functions, as well as the presentation of three-dimensional analysis, have led its applications to urban design.