# Image of a City through Big Data Analytics: Colombo from the Lens of Geo-Coded Social Media Data
## 2 Background of the Literature  
### Image of a City and Its Elements  
The public image of a city is designed by a series of physical and perceptible objects. There are other influencing factors on developing city images, such as the social meaning of an area, its related function and history, or even its name. The first descriptive introduction to the public's perception of the built environment is [PERSON]'s study on city images [23]. [PERSON] explained that in cities, 'legibility,' or clarity in visuals, makes it easier for people to navigate. Based on his case studies in three cities in the USA, he explained that public image is built on the legibility of five urban elements--so-called Lynchian elements, which are landmarks, paths, nodes, edges, and districts--described in detail below. Landmarks are a different type of point-of-reference that the observer does not enter. Instead, they are external. Additionally, they are usually a simple physical object, such as a building, a sign, a store, or a mountain [24]. Some landmarks are far away, seen from a variety of angles and distances, and used as radial references over the tops of smaller elements. Landmarks are often used as identity and even structure clues for the public, and they seem to be relied on more and more as a journey becomes more familiar. They may be located within the city or at a distance. Landmarks mostly deliver a constant direction for all practical purposes [1]. Paths are how the observer travels on a regular, irregular, or potential basis. Streets, walkways, transit lines, canals, and railroads are examples of paths. People observe the city as they move through it, and perceive other environmental elements located and related along such paths [1]. Nodes are points in a city, strategic locations where an observer can enter and exit. They can be primarily junctions, points where transportation stops, paths cross or converge, or transition points from one structure to another. These nodes serve as the focal point and epicenter of a district, radiating their influence and serving as a symbol [25]. Nodes are typically the convergence of paths and events on the journey, and they are related to the concept of the path. Nodes can be found in almost every image and can even be the dominant feature in some cases [1]. Edges are the linear elements that the observer does not consider to be a path. They can be defined as the linear breaks in continuity between two phases: shores, railroad cuts, development edges, and walls. Such edges may act as permeable barriers that separate one region from another, or they may be seams, lines that connect two regions. Although not as prominent as paths, these edge elements are significant organizing features for many people, particularly in holding together generalized areas, i.e., the outline of a city by water or wall [1]. Districts can be defined as medium-to-large sections of the city. They are expected to have a two-dimensional extent, where the observer mentally gets the feeling of entering/'inside of'. Districts are recognizable as having a unique and common but identifying character. Such districts are considered exterior references if visible from the outside and always identifiable from the inside. Most people organize their city in this way to some extent, with individual differences in whether paths or districts are the most important elements. It appears to be dependent not only on the individual but also on the city in question [1]. The works done by [PERSON] emphasized the psychological need of people for contact with other people. [PERSON]'s ideas about the thoughtful design of spaces to encourage social contact are acknowledged in the works of many key urban designers from his time and after [26; 27]. Despite being criticized for more focus on the physicality of spaces, the underlying thought of the whole body of works that [PERSON] produced lies in the core idea of creating aesthetically appealing and psychologically satisfying spaces that satisfy human needs for social contact.