Enlightenment from street art activities in urban public space

With the continuous development of society and cities, people ’ s demand for urban public space is constantly changing, and the methods for public space renewal are becoming more and more diverse. As a ﬂ exible space renewal strategy, street art activities can not only partially update the space, increase the vitality of the space, but also improve the quality of the space and meet people ’ s needs. This paper ﬁ rst discusses the concepts and types of street art and clari ﬁ es the scope of research, Then, through the analysis of the role and impact of “ street art activities intervening in urban space ” , and ﬁ nally summing up the relevant enlightenment, to create a favorable material environment for the future art intervention space.

A Chinese scholar, Ms. An Linli, pointed out in her paper [3] the four characteristics of street art, in namely "mobility", "cultural", "spontaneity", and "aggregation". The article also pointed out that street art refers to the best skills for street performers for example musicians, painters and performance artists to perform for the public in public places, including singing, dancing, musical instrument performance, painting, juggling performances, storytelling, and other performance forms. The street art defined in this article has the characteristics of "flowability", "ornamental", "participation", and "culture". First, the place where street art takes place is urban public places like "street", due to the public attributes of a place, its occupation of space is usually temporary and changeable, and so it has considerable mobility. Secondly, street art should be ornamental. The level of performing arts is the core rule for determining whether it is called an "entertainer" (Fig. 2). Street art itself is an art culture, which has the role of cultural dissemination while being appreciation. Finally, the appreciation nature of street art has brought about its participation different from groups for example beggars, tramps, etc. [4]. The need to attract the attention and participation of passers-by during the performance is the prerequisite and basis for communication and interaction.

Meeting the needs of modern urban public life
Urban public space is a public place where people gather for appreciation, action, trading, and communication, bringing together people of different identities, races, genders and all levels. The public space of the city belongs to everyone. In the space, people meet and meet, and the entire space is active because of mutual communication and short-term common purpose (Fig. 3) [5]. Public spaces in a city traditionally refer to the city's central square, the city's main streets, street gardens and theaters, and large physical trading venues. These spaces for people's activities together constitute the public space of the city.
In today's society, people will create shared spaces where more people can participate and interact according to their lives and learning styles. These new types of urban public spaces exist in public media, for example information networks, cable television, and electronic magazines, and these media are called online public spaces [6]. However, people in reality have a permanent need for face-to-face group life and social communication in a real space. The intervention of street art in urban public space can not only add vitality to the existing urban space, but also be an art method that is easily accepted by people. The current social and cultural diversity determines the existence of multiple forms of street art. The involvement of street art in urban public space also provides a new dimension for the development of street art.

Promote people to stay and communicate with each other
There have been many changes in people's understanding of public space. Public space in a city no longer simply means urban public space in the traditional sense. People more need to create diverse and even impromptu shared spaces for public participation and interaction according to their own environmental conditions and lifestyles. Moreover, contemporary public space has been hidden to a considerable extent in other public media, for example electronic networks, television, newspapers, and so on. The form of public space has formed a pluralistic, dematerialized or nonfixed existence. But street art is just a way of linking the two, It can not only timely update and supplement the traditional urban public space, but also an art method that is easy to be recorded and disseminated by modern tools.
Street art can not only shape the quality of the physical space environment, but its rich art forms can also promote the exchange of people in the space. The artists face their live performances in public spaces through creation, and actively interact with audiences through viewing, donation, and language exchange. On the one hand, the performance of street artists themselves creates an atmosphere of space; on the other hand, the interaction between street artists and audiences has formed a double involvement in the spirit of public space.

Flexible and changeable ways to enrich urban art and culture
The expression of street art in urban public space has become rich with the continuous development of society. Traditional street art performance styles are gradually being replaced by modern performance forms and interactive art. At the same time, there are various ways of presentation. In addition to being a heritage to art culture, it is also an important way for art culture to spread. Street art also continuously promotes the renewal and development of art culture, which will directly receive feedback from the audience. Street art has played a positive role in the creation of urban public places, and street artists and citizens are reaching a harmony. Street art culture promotes the spread and presentation of urban culture. Street art can not only become a city's unique cultural business card, but also help cultural expression (Fig. 4) [7].

Space use behavior triggered by viewers
The essence of street art performance is to be able to gain recognition and interaction from the audience. The expression form of street art directly affects the audience's behavior of stopping and watching. These behaviors are not only related to the expression form, but also directly connected with the layout of urban public space.
During the street art performance, the audience will watch the side and front of the street art performance. In flat terrain public spaces, people like to sit down in a space to rest and then face the direction of the performance. Even if the distance is farther from the artist, this will not affect their viewing and listening, and this distance also gives the audience the conditions to discuss while watching, while retaining the distance to interact with the artist. Standing viewers will choose their stopping position based on their sight. Some viewers like to stand in areas where objects rely on them (Fig. 5) [8].
Different forms of street art will induce different usage behaviors in different types of urban public spaces. For example, a weekend street art event party on the Liberty Bridge in Budapest, the bridge's main transportation space. Liberty Bridge forms a venue for street art weekends through a temporary function replacement strategy. The free and joyful atmosphere allows people to choose different ways of  (Fig. 6).
In urban public spaces, the layout and design of spaces influence the interaction and feedback of the performance of street art. Surrounding the stepped space layout is conducive to the audience's focus on artistic performance, and also allows the audience to obtain a relatively good viewing angle, and it is easier to generate interaction and feedback. Seating units in the Vienna Museum District in Austria, which are distributed in public spaces. The chair itself is a work of art, which attracts many visitors to stay and rest (Fig. 7). At the same time, they can also watch the street art performance in the public space. In a similar environment, it is easier for tourists to get a relaxed state. Therefore, the intervention of street art in urban public space has a close relationship with the layout and design of the space. A reasonable space layout can better provide a more ideal place for street art to participate in urban public space.

Space use behavior triggered by performers
For street performers, a good venue is the key to success. Reasonable public space layout can create favorable conditions for street art to intervene in urban public space, increase the income of artists, and at the same time allow audiences and artists to interact better. The spatial characteristics of the venue will also influence the choice of street art performance forms. The combination of choosing the appropriate performance form and the shape of public space can make the content and characteristics of the performance more distinct, and it is easy to get the audience's approval and deep impression [9]. There are several ways for street art to choose a performance area according to the form of public space: 1. In the semi-open public space, the artist will choose a relatively backward position, but not too far away from the pedestrian's sight. In this way, sufficient public space for activities is reserved for the audience and pedestrians, and it is easier to attract pedestrians to the semi-open space and make up for the missing parts in the semi-open space; 2. In public spaces where traffic lines cross, they will choose public areas close to both sides of the space. This will not only preserve the normal commute of the public space during performances, but also promote pedestrians to stay and stop, increasing their interaction Opportunity to stimulate the vitality of public space; 3. In the urban street space, the choice of street art will be limited by the size of the street space. It can only be selected on both sides of the street, and the pedestrians watching cannot affect the normal traffic. Although the mobility of pedestrians and cars in the street space is relatively strong, which is not conducive to the stay and viewing of the audience, street art can increase the fun of the street space within a reasonable range and allow pedestrians to have different life experiences. Therefore, the intervention of street art in urban public space can optimize space functions and supplement the deficiencies of the original space layout (Fig. 8).

Base on the result and findings of the studies
Through the effective ways of street art to intervene in urban public space, some planning strategies have been refined, including centralized and decentralized complementary spatial layout models, rigid and flexible behavioral restraint mechanisms, active public opinion guidance and strict law enforcement guarantees. Street art has great dependence on urban public space, so the spatial layout of street art should be closely integrated with the distribution pattern of urban public space. Centralized and decentralized complementary spatial layout patterns. Street art performances must be controlled and managed in a planned manner. The disorderly distribution in the various public spaces of the city not only fails to play its role, but also causes distress and annoyance to people and gives public space has a negative impact. Therefore, it is necessary to carry out statistics and analysis on urban public space, formulate a regular rotation mechanism in public spaces with sufficient conditions, and maintain the update and fair distribution of performance content.
The combination of rigid and flexible behavior restraint mechanism refers to the management agency adopts a loose and strict approach to the management of street performers. On the one hand, the management agency strengthens the sense of responsibility and establishes a strict system for management and control; on the other hand, the management agency confirms the legitimacy of street performers and provides more humane help for street performers and encourages them formal development. At the same time, the management agencies should also give some loose conditions to street art to encourage the emergence of new street art performances.
Urban public space is the social soil for the development of street art, so increasing the income of artists is also a very important condition. The management agency should encourage and guide the public to appreciate the habit of paying for performances, and adopt a more tolerant attitude towards the artist group; payment behavior is not only a way of encouragement and support, but also recognition of artists, which is conducive to improving the street art intervention space quality [10].

Promote the role of economic development around the site
Street art on the development of the surrounding business has a stimulating effect, urban public space for the audience Performance in public space combined with transportation; 3. Performance in urban street space (Source: Honghao He) to provide rest facilities; this will increase the length of time the audience stays. The presence of the audience will bring business opportunities to the surrounding commercial space, Not only can the audience get good consumer service, but also they can enjoy the visual experience of street art. Similarly, it is also conducive to street art to gather people and create a good atmosphere of public space. Street art also drives other business opportunities for the city, and a cultural industry chain will form behind it. For example, some manufacturers selling audio equipment, because of the popularity of street art, the number of sales will gradually increase, bringing economic growth. There are also consumables for other performance items, for example magic props, painting and handicraft consumables, etc., which have brought economic growth (Fig. 9) [11].

What do the above three points mean to the architectural approach of the design concept
Street art is a way of replacing functions in a space, giving public spaces a temporary function by organizing performances, and also increasing people's different experiences and freshness in the past. For urban public space, street art is also a "micro-renewal" strategy for small-scale, quickresponse, and more economical spaces.
In fast-growing cities, many public spaces appear to be idle, abandoned, and aging. If the urban public space is only blindly seeking to update the appearance of the space, it will not bring lasting spatial vitality. Therefore, the urban public space renewal can try to use street art to intervene in the space of "micro-renewal" strategy, to carry out artistic intervention in some lack of vitality. First of all, it needs to attract people's attention. After the public space gets attention and there are a certain number of crowds, then it starts to renovate according to the existing problems in the space and stimulate the vitality of the public space.
For cities lacking public space, suitable urban spaces can be selected for replacement and transformed into temporary public activity spaces. This will not only increase public space to provide venues for citizens, but also effectively activate some spaces, make citizens aware of the public space around them, and alleviate the problems of shortage of public space and insufficient funding for renewal in developed cities [12].

Building a public space suitable for street art intervention
In recent years, with the development of public art and the practice of community landscape construction, many countries and regions have begun to use artistic methods to reshape the community environment. In the process of reshaping and constructing urban public space, it can be used as a design reference according to the characteristics of street art and the habits of audience viewing.
First of all, in the process of constructing a new public space, keep some relatively open areas. Considering the possibility of multiple uses in the future, ensure that the public space can be fully used. Secondly, by analyzing the site's shape and surrounding related information, design a shared space that is conducive to enclosure, viewing, staying and interaction. The quality of the performance area not only affects the artists who use the space, but also directly affects the quality of the performance, thus failing to achieve the effect of street art intervention in the space. When constructing resting spaces in public spaces, they can be distributed according to the viewing habits of the audience. For example, the seats can be distributed around the performance area in a centripetal trend, or the stepped viewing space can be designed using the terrain height difference. These construction methods can optimize the quality of viewing behavior, which is beneficial to people's gathering and interaction (Fig. 10).

CONCLUSION
Street art originates from, grows on, and acts on urban public space, approaching, affecting, and benefiting the lives of citizens. Street art abandons the previous high or flashy impression of art, and instead seeks the connection between people and people in a larger city. It can not only meet the needs of modern city's public life, prompt people to stop in the busy life, stop to communicate, but also a reflection of urban art culture, deepening people's impression of the city. The intervention of street art in urban public space can improve the function of the space, stimulate the vitality of the space and achieve the role of renewing the space. At the same time, street art activities need to continue to be further improved in terms of organization, management, security, etc., and use their positive role to create new opportunities for urban public space renovation, functional replacement, and economic development.
The purpose of this article is not to design public spaces specifically adapted to street art, but to explore and analyze the phenomenon in urban public spaces through these occasional street art performances. It has brought some influence and inspiration to urban public space. At the same time, it also provides diversified choices and references for future public space planning and landscape design, so that urban public spaces can meet the daily use needs of modern people and the needs of urban regeneration. With the help of these incidents of accidental artistic intervention, the experience and fun of public spaces are enriched. Therefore, street art plays a positive role in the renewal and increase of vitality of urban public spaces, and it can improve the quality of urban life, while creating flexible, relaxed and diverse urban public spaces.