## 1 Introduction
### Tall Buildings and Visibility  
[PERSON] and [PERSON] [2] believe that \"the visual impact of tall buildings on urban form extends far beyond their footprints\". In architecture and urban studies, visibility is a criterion that deals with whether a building or an urban structure is visible from urban public spaces, to analyze its impact on the viewers [6]. This analysis calculates the visual impact of structures and buildings with the aim of controlling their impacts on the city. London is one of the cities that has specific regulations on controlling the impact of tall buildings on urban views. The London View Management Framework (LVMF) includes strict regulations that control the possible effects of proposals for new buildings on the skyline and views in London. It proposes four kinds of views, including London Panoramas, Linear Views, River Prospect, and Townscape Views. Proposals for new buildings are assessed for their impact on the protected views within the foreground, middle ground, or background of those views [7]. Tall buildings and city skylines are essential components of these views, and in most cases, tall buildings are the most prominent parts of the city skyline [8]. [PERSON] and [PERSON] [9] evaluated the dominance of tall buildings in new developments. They considered how much a tall building could influence visibility, using both traditional and modern methods. They believe visibility and dominance are fundamental options for locating tall buildings in cities. The question that \"a building how much and how long would be visible for citizens\" will be examined in analyzing visibility and dominance. [PERSON] et al [10] developed a method to study the impact of the form and the physical features of tall buildings on citizens based on Height, width, and height-to-width ratio. [PERSON] [11] provided and evaluated different methods of describing a building's visual impact on the city. [PERSON] et al. [12] examined the relationship between tall buildings' locations and the urban landscape. They evaluated the effectiveness of single and cluster tall buildings based on functional, identity, and aesthetic purposes. Traditional visibility considers if urban elements are visible or non-visible; however, [PERSON] (1966) does not agree with this definition. She believes, instead, that visibility is how much of a tall building is visible, and considers that as a measure using fuzzy logic (1966). In another study, [PERSON] (1966) examines the percentage of visibility and its importance as two critical things in visual analysis. [PERSON] and [PERSON] (2007) showed how a planned tall building's impact can be evaluated through GIS-based visibility and dominance analysis. To make the visibility of tall buildings more practical, they explain the dominance concept based on the distance of the building from the observation viewpoint. They believe that traditional visibility analysis calculates the relationship between buildings and the existing situation in the urban landscape, in which visual obstacles, trees or other disturbing elements are considered. However, dominance analysis adds the criterion of how a building dominates visually, taking into account the distance from the building and the degree to which the building is visible from any point of view (2007). Another study did a visibility analysis of high-rise building development, using a GIS-based map to present visual coverage and cumulative visibility of tall buildings through the study of visibility of existing single and cluster buildings in the city of Rotterdam, and the impact of those buildings on the city skyline during the time (2010). They considered a tall building's performance in the cluster, which is perceived visually instead of obtaining it individually; this offered a new way to characterize the visibility of a tall building. [PERSON] and [PERSON] (2011) offer the visual impact size (VIS) method to recognize tall buildings' locations and to determine how much tall buildings are visible through virtual city models.