Research and Evaluation of the Mountain Settlement Space Based on the Theory of “Flânuer” in the Digital Age —— Taking Yangchan Village in Huangshan City, Anhui Province, as an Example

ABSTRACT The theory of “flânuer” originated in the fields of philosophy and social sciences. In recent years, the term has been extended to research on built environments and has been developed as a walking-based research tool for the civilian built environment. Flânuer integrates the subject constructing and the object experiencing the space, exploring the spatial needs of humans from physical to spiritual aspects. In the digital age, “flânerie” has been expanded to virtual spaces through data footprints, providing an opportunity to transform “walking” research from a purely phenomenological space research method to a scientific framework that integrates subject and object, quality and quantity, and data and art. As typical built environments constructed through the aboriginal people’s walking, participating and interacting with mountain landscape as well as different kinds of rules, this mountain settlement then triggers tourists’ flânerie experience, and provides an opportunity for the development of the theory and practice of flânuer. This study starts from the construction of the settlement space that triggered by interaction between the aboriginal’s flânerie and daily life with environment in Yangchan Village, a mountainous Tulou settlement in She County, Huangshan City, Anhui, analyzes the spatial characteristics of the settlement of Yangchan that spawned from walking from the perspectives of the multidimensional theory and concept of flânuer in the digital age, and then objectively evaluates the value of the resulting mountain settlement in guiding people’s flânerie experience and promoting emotional associations by integrating multiplatform data mining, analysis and calculation. On this basis, we excavate the construction wisdom of Tulou settlement in Yangchan, which originated from the interaction between the individual and the site, to provide a reference for their protection and further development, to more subjectively assess the value of research and design for mountain settlements based on data assessment, and to improve the multidimensional methodological framework of flânuer in the digital age.


Introduction
Settlement is the product of organic evolution after people live together and multiply in nature."Book of Han: Gou Xun Zhi" recorded that "After a long natural disaster-free period, houses were built, and gradually settlements were formed".A settlement reflects people's multiple needs for a built environment in the form of space and has been the carrier of material civilization since ancient times.Diverse traditional Chinese settlements have utilized the construction wisdom stemming from thousands of years of Chinese civilization, applying such knowledge to local conditions (Liu 2011;Qing and Wang 2021).Notably, mountain settlements, which originated from the interaction between constructors and the sites through physical walking, are particularly prominent as a representative example of built environments of traditional Chinese villages where humans and nature are integrated.Existing research on mountain settlements in China and abroad is rich in content, with diverse perspectives ranging from material entities to economic culture (Wang, Wei, and Mao 2017;Zhao, Chi, and Wang 2018;Zhou and Nong 2018;Xiaojian et al. 2021) and from built environments to virtual spaces (Li 2020;Jia and Zhou 2019;Loujun, Yang, and Xiong 2022), and the analysis of space ontology shows a trend of multidisciplinary integration (Chen et al. 2022;Juan et al. 2021).However, returning to the origin of mountain settlement construction behavior-walking -research has rarely addressed the specific characteristics of the occurrence, development, and formation of the walking space, which however are the direct drivers for built environments to meet users' preconscious perceptions and multiple cognitive needs through materials and are important perspectives to understand the spatial value of traditional settlements and promote their tourism development (Huang, Lin, and Song 2021).In recent years, the concept of flânuer, which started in the fields of philosophy and sociology and expanded to the fields of architecture, urban planning, geography and tourism, has been applied to walking-based research from a civilian perspective (Zhang and Zhuang 2016).Therefore, the definition of Flânuer as a systematic spatial research method in this study has developed from a simple urban bystander originally from Baudelaire to an observer, builder and experiencer consisting of space.This is also the basis for the introduction of its theory and method in this paper.Flânuer can be both the subject constructing and the object experiencing the space.Flânuer (flânerie) integrates the spatial needs of people from physical to spiritual aspects.For the former, it is embodied in the transformation of nature and the construction of settlements on a physical scale through walking.Flânuers here through participating in, dominating or adapting to the original environment constraints to influence the spatial form of environment, instead of being idle observers.For the later, Flânuers represent both individuals and groups, their behavior respond to local culture, which affects their construction and experience of the environment.In the digital age, flânerie has been expanded to virtual spaces, providing a theoretical and methodological basis for this research.
This study starts from the construction of the settlement space that began with individual as well as communal flânerie in Yangchan Village, She County, Huangshan City, Anhui Province (the only well-preserved "unorthodox" mountainous Tulou settlement among the Huizhou-style settlements in southern Anhui), analyzes, from the perspective of flânuer in the digital age, the spatial characteristics of the mountain settlement of Yangchan that were spawned by aboriginals walking and interacting with both physical and cultural environment both in ancient times and in recent times, and then evaluates the value of the resulting mountain settlement in guiding people's embodied flânerie experience and promoting emotional associations by integrating geological research and multiplatform big data mining.On this basis, we excavate the construction wisdom of the Tulou settlement in Yangchan, which originated from the interaction between the aboriginals and the site and then developed responding to necessity and time, to provide a reference for its protection and tourism development, to more subjectively assess the value of research and design for mountain settlements based on data assessments, and to improve the multidimensional methodological framework of flânuer in the digital age.

Researches on the concept of flânuer from multidisciplinary perspective
Flânuer is of French origin, and its root "Flana" means "to stroll aimlessly".The character "Flânuer" first appeared as the protagonist in a poem by the French writer Charles Baudelaire; "Flânuer" was described as a person who observed people's behavior by strolling among the crowd (Shangguan 2014).Subsequently, Walter Benjamin, in his masterpiece The Arcades Project, further gave flânerie (flânuer behavior) a critical and speculative connotation, using flânuer as a term in sociology, psychology, literature and film, etc., for the study of urban spaces via walking, serving as a unique way of revealing the relationship between people and the environment (Benjamin and Benjamin 1999).
The study of flânuer began in the fields of literature, social science and philosophy, and researchers who have delved into the topic believe that flânuer represents the public's demand for individuation and resistance to consumerism in the crisis of postmodern scientific rationality, idealization and meta-discourse and is a sign of late modernity and urban autonomy (Giddens 1990).In recent years, due to its unique walking-based spatial exploration method, flânerie has been used to identify characteristics of civilianization and humanism, conforming to the appeal of conscious experience and the return of humanism in postmodern built environment research.Therefore, some researchers and designers of built environments have introduced flânerie into architecture, urban planning, geography, and tourism-related research (Zhang and Zhuang 2018;Elliott 2010) and developed a methodological framework that integrates flânerie and quantitative methods based on big data platforms in the digital age.As a spatial research tool, flânuer is a combination of "phenomenon" and "evidence".Regarding the former, flânuer is a research approach that embodies spatial analyses through walking, who allows dialogs with people, the built environment and subtle rare things (Featherstone 2021), and meticulously records and analyzes random events in street space (Shortell and Brown 2016).Combined with traditional research methods and conscious experience, flânuer as a research tool can be used to more scientifically acquire and analyze the "spirit of a place".Regarding the latter, a flânuer is a civilian who observes either individual or collective usable spaces.Flânerie is the way a flânuer or a group of flânuer experiences and changes space.Research on individual or group flânerie behavior provides an important reference for designers.The recording and analysis of the evaluation, trajectory and other data by big data platforms in the digital age makes flânuer truly scientific "evidence" of design (Niu and Silva 2020;Souza et al. 2019).
In addition to flânuer, the concept of walking in a city proposed by the social historian Michel de Certeau (De Certeau and Rendall 2004) and the strollology theory constructed by the Swiss sociologist Lucius Burckhardt (Burckhardt 2015) are also spatial research methods based on walking.Some researchers of built environments often use the terms "stroller" and "flânuer" interchangeably.In fact, looking at the origin, temporally, flânuer appears before stroller and has an enlightening effect on the latter.Methodologically, flânuer involves walking, emphasizing the use of individual interactions to gather new information and thus redraw cognitive maps and blend in with the space in which it is located.Stroller is not limited to walking, riding and driving beyond the scale and speed of the human body are integrated into "strolling" (Fezer and Schmitz 2016).The Tulou settlement in Yangchan, the subject of this study, is a mountain settlement that originated from the interaction between people and mountain landscape.The aboriginal villagers reclaimed the mountains and built Tulou buildings only rely on walking, so the scale of Yangchan was mainly determined by "walking" and even till now, the roads and streets could not meet the needs of vehicles, and the transportation of materials still mainly depends on manual walking.Therefore, such spatial structures especially trigger the experience of walking of people and tourists visit here later.The concept of flânuer is more in line with the formation logic of settlement space, and its bottom-up civilian perspective coincides with the big data approach in the digital age, which is conducive to the development of spatial research with walking as the core, from a purely phenomenological method to a framework system that integrates subject and object, quality and quantity, and data and art.

Researches on the flânerie-style spatial construction and spatial experience methods
Flânerie is the behavior of a flânuer, who explores spaces.Some researchers describe flânerie as "walking through spaces to satisfy a desire for observation, a sense of presence, and a way of perfecting identity".Walking and observation are inseparable components of flânerie: the former is the multidimensional interaction between the individual or group and the site in time and space, including both site transformation driven by preconscious needs and travel and arrival with subjective intent, while the latter has a deeper connection with space at the cognitive level, integrating sense and sensibility and to record, explore and analyze the random surprises that spaces offer in constant emotional immersion and extraction.Therefore, the core of flânerie is to interact with a site at the scale of the human body, not only in space but also in time, not only for individual but also for group -walking is an organic integration of the two.
Flânerie-style walking is the behavioral manifestation of a flânuer's conscious experience, highlighting the dual characteristics of the unity of subject and objectit is not only the subject with distinct personality and independent thinking among the common people but also the object generating the behavioral big data in research.The former is reflected in its construction of spaces, while the latter is derived from the experience of spaces.Flânerie-style space construction is based on the transformation of a site based on the scale and walking speed of the human body, and then developed according to physical and cultural constraints mediated by communal or superior authority planning decisions.The forms of traditional settlement space before the intervention of mechanical production equipment and digital construction technology are the most direct reflections of flânerie-style space construction.Notably, mountain settlements are particularly representative.The scales, elevations, associations, and transitions of paths, houses, fields, and public spaces are derived from the interactions between people and sites through embodied interactions between flânerie and sites over hundreds of years, including both dynamic and static interactions, which originated from preconscious physiological needs and meet social and cultural needs, while they also respond to the rules of the old community and the plans of the later administration.Flâneriestyle spatial experiences are created by flânuers, individual as well as communal.In terms of space, in addition to the built environment researchers and designers who subjectively examine spaces from the identity and perspective of flânuers, most flânuers are common people who use the spaces.To this end, the morphology and ontology of spaces become the key to whether users can naturally flânerie to perceive and recognize the "unexpected surprise".These spaces also reflect the influence of society, culture and changing times.In the digital age, this experience is intentionally or unintentionally recorded on big data platforms through multidimensional footprints such as texts, pictures, and videos.Mining and analysis can provide bottom-up evidence for the value of interactions with space in triggering emotion.

Researches on the multidimensional flânerie methods in the digital age
In the digital age, the value and methodology of flânuer have extended from the built environment to virtual space.Regarding value, "civilian" and "humanism" values are not only reflected in the respect for the unique "conscious experience" of ordinary individuals but also emphasize the attention to the orientation of public opinion at the level of multidimensional data statistics; for the latter, walking and observation are not only the main qualitative research methods for flânuer as the research subject but also intentionally or unintentionally recorded on big data platforms through multidimensional digital footprints (such as texts, pictures, and videos), thus providing researchers with bottom-up mining and analysis of people's demands for spaces and the impact of spaces on people (Yuan, Guo, and Chen 2022) and adding a more objective and scientific quantitative perspective to the methodological system of flânuer.In addition, it also provides a reference for the further renewal and development of the built environment such as Yangchan, which responds to the needs of contemporary people and society.

Research object: Yangchan, a mountain settlement space spawned by flânerie
Yangchan is in Shendu Town, She County, Huangshan City, Anhui Province, and contiguous with the Longwangjian and Beishan mountains (Figures 1-2).The Tulou settlement in Yangchan is one of a limited number of existing Huizhou-style Tulou settlements located on mountain slopes.In ancient Huizhou dialect, "Yangchan" means "steep slope under the sun"; the settlement in Yangchan was built in a mountainous area with an area of less than 100 hectares and an elevation difference of 475 meters, with a very small actual buildable area.Over the past hundred years, the villagers in Yangchan have constantly adapted and transformed the mountains based on their needs of survival and daily life through flânerie, as well as physical and cultural constraints mediated by traditional communal and later superior authority planning decisions, then spawning Tulou buildings, roads, fields and communication spaces that have become organically integrated.Due to limited flatland, Tulou was not designed for large planar width or depth but for vertical growth.Roads were "walked" out during construction, following the contour lines; Tulou buildings were built perpendicular to the contour lines, along which buildings, fields, mountains and streams were connected.The limited flatland area was used as farmland or as spaces for communal activities such as traditional ancestral hall commemoration activities and "sun-drying produce in autumn" activities, becoming "stops" during walking as well as places of collective spirit.As a result, Yangchan "grew" from the mountains due to flânerie.The morphology and scale of its space are an imprint of the interaction between people and the environment and have been continuously updated and iterated with the changes in the times (Figure 3).At present, with the intervention of outsiders and assets and the development of tourism, some Tulou buildings and mountain environments have been transformed into new spaces, such as cafes and homestays that are more in line with the needs of contemporary people.Today, this settlement space has triggered the embodied flânerie of foreign tourists and has thus become an appropriate and valuable subject in the study of the flânuer horizon.

Research methods: "flânerie" integrating onsite experience and data evidence
In addition to the aforementioned value orientation and logical framework, the concept of flânuer in the digital age is used in this study as a research method that integrates qualitative and quantitative approaches, on-site experience and empirical data.Regarding the on-site study, "flânuer" is used to represent not only the aboriginal people who built the Tulou settlement through walking individually and collectively in the mountains, but also the researchers who used the theory of flânerie to study the spatial characteristics of Yangchan.The former has built up a unique and interesting settlement space in Yangchan through constantly adapting and transforming the mountains based on their needs of survival and daily life, responding to physical and cultural demands, and the latter has used flânerie to explore the spatial characteristics of Yangchan and the construction wisdom of the former considering the local morphology.To this end, individual scale, walking speed, and observation method and the collective spirit of place related to local culture started with construction through flânerie and ends at the starting point of this research on flânerie.
In data mining, flânuer represent tourists who visit Yangchan.Yangchan provides opportunities for tourists to flânerie intentionally or unintentionally through its diverse and rich spatial forms.Tourists' experiences are expressed in one-dimensional semantics and twodimensional images or videos recorded and published through various social media platforms, becoming a multidimensional flânerie data footprint.Hence, through the mining and analysis of multidimensional data, we can explore the value of the abovementioned spatial features in inducing tourists' spatial experiences and in establishing emotional associations in a bottom-up manner, providing an objective public evaluation of the built environment.Based on minable data features and analysis techniques, sentiment and semantic analyse are used herein to analyze the multiplatform evaluations of Yangchan.Specifically, frequency in text messages reflects the attention of tourists to relevant spatial nodes or features, and the size of emotional computing data reflects the intensity of tourists' emotional experience.The process of sentiment semantic analysis is shown in Figure 4.
Reviews about the Tulou settlement in Yangchan were selected from six major review or public social media platforms: Ctrip, Mafengwo Travel, Dianping, Meituan, Xiaohongshu and Weibo.Python was used to perform data mining and cleaning of the collected texts.A total of 736 valid sample data points were obtained.The data collection time started on 10 July 2016, when Yangchan started to be protected and developed as a traditional settlement tourist attraction, and the data collection ended on 10 November 2022.The NLPIR-Parser big data semantic intelligent analysis platform was used to preliminarily segment the comment content, and after filtering out meaningless words, statistical results for highfrequency words were obtained, and high-frequency words with the same semantics were merged.
High-frequency words classified using different evaluation scales and A Dictionary of Chinese Praise and Blame Words were screened by intersection with the Simplified Chinese Version of the National Taiwan University Sentiment Dictionary, the Chinese Emotional Vocabulary Ontology Database, and the China HowNet database (CNKI).Then, similar words were merged using A New Chinese Synonym Forest.After screening, the intensity of each word was used to define its emotional intensity, and the evaluation indicators were divided into four types: commendatory words (intensity: +1, +2, +3, +4, +5), derogatory words (intensity: − 1, −2, −3, −4, −5), neutral words (intensity: 0), and special words (words not included in the dictionary).The emotional intensities of commendatory, derogatory, and neutral words not included in the dictionary were uniformly marked as + 3, − 3, and 0, respectively.

Methodology framework
Figure 5 illustrates the methodology framework of this study.The study focuses on the traditional mountain settlement space characteristics analysis and evaluation through the perspective of "Flânuer", which representing both aboriginals who construct the settlement by interacting with mountain space through walking and responding to cultural and communal rules, and tourists who experience the settlement.The former is further developed as the on-site qualitative space research method from a top-down perspective to dig out the spatial structure, both individually and collectively, while the latter provides huge amount of digital footprints and comments online and are used for data mining to evaluate the value of the settlement space from a bottom-up perspective.It adopts the logical path of "criteria establishment-methodology construction-results processing" to analyze and evaluate the traditional settlement space forms constructed by walking, while comprehensively revealing the space value of traditional Chinese mountain settlement combining the qualitative onsite flânerie analysis and quantitative data mining results.

Spatial construction that begins with flânerie: Analysis of Yangchan's settlement spatial structure
The aboriginal people adapted and transformed the mountains through walking and "lingering".In this process, the distribution of road space and Tulou buildings suitable for body scale and ensuring convenient and safe production and life is the leading rule of settlement construction under this circumstance.The settlement spatial structure is analyzed based on this driver.The scale, speed, and on-site experience through flânerie are used to classify, analyze and explain the space structures and forms.

"Exploratory movement" on an individual scale: the formation of linear walking spaces
The distribution of different structures of linear walking spaces is shown in Figure 6.
(1) Street spaces without height differences • Non-enclosed connection spatial structures Non-enclosed connection structures are in the form of narrow bridges (Figure 7).This type of space is not influenced by traditional culture or collective rules, and basically reflects the characteristics of the scale of the body itself.The need for convenient and fast walking has caused people to choose bridges to pass over small gaps between cliffs.The bridge size (approximately 0.8-1 m wide) allows the rapid passage of one person, and the bridges are often distributed between the Tulou buildings and the cliffs.The steep mountains cause the ground on two opposite sides of most Tulou buildings to be at different heights, and the height difference between the two sides may exceed one story.Villagers often directly enter the second floor of Tulou buildings by crossing the gaps between the cliffs and their houses or between retaining walls and house facades using bridges.Interestingly, some small Tulou buildings have become connection points in three-dimensional traffic patterns. •

One-side enclosed spatial structures
There are two types of one-side enclosed street spaces: active construction and passive formation.
The former is derived from the remaining linear space after flânerie around the narrow intermountain flatland to build Tulou buildings; the latter is formed by the loss of lateral interface enclosures due to defects in Tulou buildings or gaps caused by the collapse of Tulou buildings.Same as the above, the form of this type of space is mainly affected by the scale of the body, but it can be found that part of the road near the cliff wall is widened or even enlarged into a prominent small platform, which makes the spatial form "mutated".This is due to two reasons:  first, some villagers use electric tricycles instead of manual transportation of goods, and some of the unilateral enclosed roads that are main roads need to be widened to ensure safety; second, the development of tourism has made the one-sided enclosed space an excellent viewing point overlooking the Yangchan village, and subsequent developers have opened up some viewing platforms for tourists based on this.One-side enclosed streets are the most spacious linear structures (Figure 8), mostly 1.3 meters to 1.5 meters wide.Their initial morphology and size originated from slow walking and flânerie; therefore, their initial width was relatively narrow.Because one side of the street is typically a cliff, the edge of the street is prone to collapse due to soil erosion.For safety reasons, large bluestone slabs have been laid to serve as curbs and subjected to anti-slip treatment.Therefore, the one-side enclosed streets have become spaces for the main pedestrian flow in the development of Yangchan, and because the open side faces the mountains, they have become spatial nodes for tourists to stay and enjoy the scenery.Their construction starts from flânerie and develop according to different rules in different times.
• Double-side enclosed spatial structures Double-side enclosed streets are linear spaces formed by the outer walls Tulou buildings (Figure 9).Their morphology derived from fast walking and flânerie; therefore, the scale is not large, mostly 0.9-1.2meters wide.In addition, the ownership of adjacent Tulou buildings also affects the form of public roads.The two sides of the street are continuous Tulou buildings, forming a relatively straight interface, which guides the multiple unidirectional components of kinesthetic, tactile, and visual attention, effectively reducing walking resistance and improving the privacy of Tulou buildings.However, this spatial structure is not necessarily a straight line.Due to the site conditions and space requirements by villagers when building Tulou buildings, individual Tulou buildings protrude or sag on the flat street facade, making some streets tortuous.The structure of such spaces is mainly influenced by the daily needs of individual villagers and the rules of sharing in the neighborhood.
• Three-side enclosed spatial structures Three-side enclosed structures are mostly located in the gaps between the rear walls of houses and retaining walls, and the plates on top of the rear walls and the retaining walls are the aforementioned non-enclosed connection structures (i.e., bridges).These spaces were formed using existing gaps that the body can just pass through based on traffic needs during settlement construction; therefore, these spaces have a small scale (0.8-1.2 m wide), and most are integrated with singleside and double-side enclosed spaces in the walking system in Yangchan (Figure 10).Furthermore, because of the strong privacy and good ventilation and coolness  of such spaces, they are also used as the main storage space for firewood.In addition to being affected by the scale and speed of walking, this type of space is also derived from unique living customs.
(2) Stairways to spaces with height differences •

Gently sloping structures obliquely crossing contour lines
Gently sloping stairways are the main traffic spaces for villagers with a normal body scale to flânerie between different elevations at normal speed and to build Tulou buildings.The gently sloping walkable stairways have been formed by obliquely connecting terraces at adjacent elevations.Most of these spaces are located in relatively open areas, with a width of approximately 1.2-2 m, ensuring that many people can traverse relatively safely or transport construction materials.Such spaces are the core components of vertical transportation in the settlement space.Because most of the gently sloping stairways were built earlier than Tulou buildings, the stairway irregularly segments the plots.
The villagers built special-shaped Tulou buildings based on the local conditions, for example, a pentagonal Tulou building (Figure 11) beside the inclined road in the northeastern corner of Yangchan Village and a Zheng residence next to a hundred-step ladder.This spatial type fully reflects the wisdom of the villagers in transforming the natural site under the constraints of steep mountainous terrain.This is today a spatial structure that limits the way visitors flânerie. •

Steeply sloping structures perpendicular to contour lines
Steeply sloping stairways often appear in the relatively wide gaps between the Tulou buildings, and their construction allows the villagers to flânerie quickly across different elevations.The villagers build steep bluestone steps across gaps that allow just one person to pass.The width of steeply sloping stairways is usually less than 1 meter, and their slope can reach 70-80°; therefore, people climb these steps with both hands and feet to ensure safety (Figure 12).These stairways are the products of passive "squeezing" or are selected are built between the walls of Tulou buildings, forming unique vertical streets in Yangchan.In  the past decade, due to severe soil erosion, some steps made of rammed earth have collapsed, and under the protection of governments and developers in recent years, they have been replaced with stone steps, but the scale has not changed significantly.

"Static observation" on an individual scale: construction of point-shaped lingering spaces
The distribution of different structures of point-shaped lingering spaces is shown in Figure 13.
(1) Gap spaces with a continuous interface   Gap spaces with a continuous interface refer to the "gaps" left after villagers built the Tulou buildings (Figure 14).Most of these gaps are intentionally preserved because of geological conditions unsuitable for construction or neighborhood property rights, and some formed after the collapse of single Tulou buildings.The former is usually no more than 1 meter in size and are distributed in the aforementioned linear streets.Through them, one can overlook the village, which ingeniously eliminates the sense of enclosure of the streets and improves lighting and ventilation.Over time, these gaps have become spaces for villagers to enjoy scenery, linger, and exchange daily greetings.People also use bluestone slabs to reinforce or widen the spaces for seating, but the number of people sitting on each slab usually does not exceed 3. The latter serve as spatial breakpoints of the continuous interface, and some have been used by villagers to dry the grains or sit around and chat, becoming spatial nodes for group communication.With the development of tourism, the government and developers have also renovated some of the spacious step nodes to provide villagers and tourists with a more comfortable place to rest and communicate.
(2) Top-enclosed terrace spaces Top-enclosed terrace spaces result from villagers' active selection and construction of lingering spaces during flânerie, and most occur when Tulou buildings on opposite sides of the street belong to the same household.These villagers set up roofs and pergolas over the streets to connect the Tulou buildings, forming spaces that include both streets and outdoor courtyards.The widened flatland on the street sides is used to accommodate dining tables or to store items.These spaces originated from the basic demands of the villagers for daily family gatherings or social interactions, and their spatial scale is relatively large.To a certain extent, the spaces are equivalent to traditional Huizhou-style inner courtyards but outside, to meet local conditions, making the spaces unique "courtyards" in the limited mountain settlement space.These "courtyards" form important social gathering nodes for settlements composed of enclosed Tulou buildings.After the tourism development, the local government and developers also assisted villagers and hotel owners to build some spaces for tourists to rest while walking and climbing the steep mountain roads of Yangchan, which were later converted into outdoor tea or coffee pavilions near these hotels (such as Yunqishi B&B, Figure 15).

Spiritual imprint of flânerie: becoming a spatial node of "place"
The construction and creation of spaces by villagers through flânerie includes both exploration based on  individual consciousness and collective experiences through traditional settlement-style production and life.Therefore, there are two types of places that demonstrate the spiritual imprint.They reflect the influence of traditional customs and historical and cultural rules on the spatial structure to some extent.In recent times, the promotion and protection of it by governments and developers has promoted its value in both the built environment and the virtual space.
(1) Places that touch individual consciousness The momentary sense of place that an individual experience in flânerie is mostly derived from immediate experiences when an individual is physically present at a place.Therefore, these types of spaces often reflect the typical spatial characteristics of the mountain settlement in Yangchan derived from the aforementioned individual scale, at the same time, they have also been protected and publicized by subsequent governments and developers, represented by hundred-step ladders.A hundredstep ladder is a stair-like structure obliquely crossing contour lines (Figure 16).Due to the relatively spacious size, unobstructed boundaries and relatively core position, hundred-step ladders have become clearly identifiable spatial nodes of the spatial mechanism of Yangchan.Hundred-step ladders connect gently sloping stairways, gaps for lingering and watching, and enclosed streets.In the material dimension, these ladders connect the typical spatial structures in Yangchan constructed based on flânerie and allow the connection of streets in this mountain environment.In the consciousness dimension, these ladders provide a variety of embodied behaviors, such as exploratory walking and static observation through flânerie.Hundred-step ladders provide a panoramic view of Yangchan.Flânerie allows a clear view of the village and of people blending in with the land, emotionally touching and resonating with people who see such views.This "charm", revealed through individual consciousness and behavior, mobilize the spirit of the place.Due to its unique spatial experience, local government and developers have also promoted it as a mustexperience attraction when visiting Yangchan, and with the rise of social media in the digital age, it has become one of the important business cards of Yangchan's tourism.Almost all travel photos posted on social media include this space.This also helps preserve these unique architect-free settlements.
(2) Places formed over time based on collective experience When flânerie develops from instantaneous individual consciousness to a delayed collective experience, people often endow a site with unique meaning through unconscious repetitive behaviors or conscious social activities, making the space a "place".The places formed through instantaneous individual consciousness are derived from the use of a site on an individual scale and speed, and the places formed through delayed collective experiences are more related to the traditional social and cultural behaviors of the settlement.The stairway shaded by ancient trees at the entrance of Yangchan is a perfect example of the places formed through instantaneous individual consciousness.These ancient trees with large crowns and shade provide a comfortable green space and a natural sense of enclosure.People tend to choose such spaces to gather.Over time, the bluestone slab road has been gradually widened for temporary sitting, and the stairs have been cleverly modified into seats and backrests.Originally, the space was for villagers who returned from work to stay briefly and greet each other.Later, it became a space for traders to rest and wait for the arrival of tourists.The accumulation of countless events and the anchoring of emotions and memories gave birth to the spirit of place at this ancient tree space.The places formed through delayed collective experiences are distributed in large and small spaces for "sun-drying produce in autumn"."sun-drying produce in autumn" is an activity of the villagers in Yangchan during which they dry produce (Figure 17), which is a basic living need.The topography of Yangchan determines that a space with a large area and flat surface cannot be used for this activity; therefore, the villagers perform this activity in every corner of the living space: a site as small as a winnowing fan overhanging a window sill, an intermediate-size site such as a terrace transformed from a roof or the flattened floor of a collapsed Tulou building, or a site as large as the plaza in front of the elementary school, temporarily used as a collective place for this activity.Traditional production activities endow these sites with seasonally changing colors and characteristics and give them a unique sense of "life", making these sites "places"."sun-drying produce in autumn" has become an important intangible heritage in the protection and development of Yangchan.As a result, the associated sites have also received attention from the government and developers in recent years, some public platforms that can accommodate more tourists have been repaired and maintained, and villagers have begun to build new window sills to dry food to attract tourists.

Spatial experiences that trigger flânerie: data-supported evaluation of spatial features
The aboriginals have built and created settlement spaces in Yangchan through hundreds of years of flânerie.These spaces derived from walking or lingering at the individual scale trigger a flânerie-style spatial experience for tourists visiting Yangchan.In the digital age, flânerie methods and experiences are intentionally or unintentionally recorded on various data platforms through texts, pictures, or videos, providing a research opportunity for flânerie methods to expand from phenomena to empirical evidence and for the subject of flânerie to extend from individuals or small collectives to groups.To this end, through the mining of flânerie experiences associated with Yangchan on open data platforms and sentiment and semantic analyses, the triggering effects of the spatial characteristics of Yangchan on embodied behaviors, such as walking, lingering, observing, and exploring, are clarified from a more objective and scientific perspective, thus proving that the spaces created by flânerie promotes flânerie exploration and thus deepens people's emotional experience of spaces.

Emotional attention to space characteristics reflected by the frequency of text
Using a top-down analysis of the spatial characteristics and organization of settlements in Yangchan, the relevant reviews were located and extracted through words associated with five types of spaces: "streets", "stairways", "gaps", "terraces" and "places".Then, the text of the reviews was subjected to word segmentation, integration, screening, and assignment calculations to obtain the tourists' emotional attention to and emotional experience intensity in different spaces.
The frequency of text was used to describe tourists' emotional attention to different spaces during flânerie (Table 1).In general, the high frequency of text associated with linear walking spaces indicates that linear walking spaces have received much attention.The low frequency of the text associated with point-shaped lingering spaces indicates that the point-shaped lingering spaces have received little attention.Among the specific space types, stairways with height differences received the most attention, followed by streets and "places"; gaps and terraces received the least attention.The emotional attention reflected by the frequency results is in good agreement with the characteristics of the spatial forms in Yangchan, indicating that the spaces constructed based on flânerie trigger the flânerie experience of tourists to a certain extent.The sentiment and semantic scores can be used to further analyze the tendency and intensity of the emotional experiences of tourists in different spaces during flânerie.

Emotional intensity to space characteristics revealed by semantic analysis results
The sentiment and semantic calculation results for the reviews reflect the positive and negative directions of emotional experiences by the positive and negative numerical values, respectively, and reflect the intensity of emotional experiences by the magnitude of the numerical values (Figures 18-19).In general, the emotional intensity values for the semantic evaluations of the studied spaces were all positive, indicating that the overall emotional experience of tourists during flânerie in the various spaces of Yangchan was positive and pleasant.The tourists intentionally or unintentionally experienced emotional changes in the process of interactions between individuals and sites and were derived from the spatial forms in Yangchan."Places" had the highest score, indicating that places embodying the life wisdom and spiritual imprint of Yangchan villagers triggered a strong emotional experience during tourists' flânerie (Figure 18).For example, sun-drying produce in autumn was associated with high attention frequency; this type of seasonal production activity in Yangchan adds a diachronic sense of life to sites, often attracting tourists to participate, expanding flânerie from walking and observation to thinking and creation.Hence, this activity has become the "keyframe" in people's descriptions and memories of the settlement spaces in Yangchan.Although the gap and terrace spaces did not receive high emotional attention, tourists had a strong positive emotional experience with them, and the scores for these two types of spaces were second only to places.The spatial distribution of gaps and terraces in Yangchan may be a reason for the low attention to these two types of spaces; they are interspersed in along linear walking spaces; therefore, they are difficult to find.However, this did not affect the strong emotional experience of tourists with these two types of spaces, indicating that as nodes representing rhythm and experience change in linear walking spaces, gaps and terraces become those "unexpected surprise experiences" during flânerie.As the main place where flânerie behavior occurs, streets received much attention, but the intensity of emotional experiences associated with streets were slightly lower than those for gaps and terraces (Figure 18,19).This result indicates to a certain extent that spaces that prompt long-term kinesthetic senses during flânerie likely create persistent but mild emotional experiences and that spaces that prompt momentary observation and thinking often generate a momentary but more intense emotional experience.The last space, i.e., stairways, received the highest emotional attention but the lowest positive emotional experience intensity.The highest emotional attention might be attributed to the three-dimensional spatial form of stairways, representing the typical mountain features of Yangchan, which are often the visual focus of tourists, arousing their physical, visual and other senses.The lowest positive emotional experience intensity mostly stemmed from the terrifying feeling brought by the cliff-like walking experience, with words such as "steep", "tortuous", and "rugged" occurring at high frequencies in reviews.The digital footprints of tourists' flânerie demonstrates that the characteristics of the settlement in Yangchan promote walking, observing, thinking and creating during flânerie, thus triggering emotions, from a bottom-up review manner.These evaluation and appeal of the public have also become a new rule for indigenous flânuers to choose the way of protecting and developing Yangchan settlements nowadays.

Conclusion
To summarize, based on the concept of flânuer, this paper analyzes flânerie as a walking-based construction, research and evaluation method for the built environment in the Tulou settlement in Yangchan, a unique mountain settlement in southern Anhui that was spawned by hundreds of years of flânerie with responding to changing rules from necessity, society, culture, government, developer and time.The settlement then triggered later generations' flânerie experience, and improves the theoretical framework by integrating quality and quantity and expands the application scope of flânerie from physical spaces to virtual spaces using big data logic and technology in the digital age.The research results show that the spaces constructed based on flânerie trigger walking, observation, thinking and creation through a morphological structure that conforms to the scale and speed of the human body and provides people with a good emotional experience.In ancient times, the rules affecting the formation of Yangchan spatial structure are more derived from the appeal of the human scale in the process of flânerie, which is reflected in the transformation based on the basic needs of survival, production and life.While in recent times, the intervention of government protection and tourism development has further promoted the protection of the unique spatial form of Yangchan as well as the construction of spatial nodes affected by cultural customs, while the evaluation of tourists in the digital age has further influenced the spatial transformation decisions of groups and villagers.Specifically, a space that is a visual focus can easily arouse higher emotional attention during flânerie, the organic combination of point-shaped lingering spaces and linear walking spaces can create unexpected surprises during flânerie and enhance tourists' emotional experience intensity, and activity and events endow the space with a unique character, turning sites into places.
Overall, the value and significance of this study is manifested in the following three aspects.Firstly, the study provides a reference for the protection and development of traditional villages represented by Yangchan.Moreover, in terms of the methods of built environment design and research, the study constructs a method to more subjectively assess the value of research and design for mountain settlements based on data assessments.Last but not least, the study helps improve the multidimensional methodological framework of flânuer in the digital age.This study is a demonstration of Yangchan's construction experience and wisdom as a traditional Chinese village that has adapted to local conditions and integrates nature and humans.Mining and analysis of multisource reviews demonstrate the value of the built environment in triggering emotional experiences from a more objective and universal perspective and provide a more scientific reference for current humancentered spatial design and research.
At the same time, this study still has the following limitations, which can be further explored and improved in the future.In terms of data collection, the amount of the existing big data concerning Yangchan is still insufficient, and the existing analysis only uses the dimension of text evaluation, which may affect the comprehensiveness of the results.In the future, the types of big data mining platforms and the types of big data itself can be expanded, such as mining and analysis that add image and video dimensions.In terms of the methodological framework of flânuer, the breadth and depth of existing data in this study to a certain extent limit the degree of translation of flânuer from theory to spatial analysis methods, and in the digital age, the future study may combine emerging technologies to collect and analyze more diverse data, such as eye trackers, wearable portable physiological instruments, etc.

Figure 2 .
Figure 2. Surroundings and enlarged view of Yangchan village.

Figure 4 .
Figure 4.The process of sentiment semantic analysis.

Figure 5 .
Figure 5. Methodology framework of the study.

Figure 6 .
Figure 6.Distribution of different kinds of linear walking spaces in Yangchan village.

Figure 7 .
Figure 7. Diagram and example of non-enclosed connection spatial structures.

Figure 8 .
Figure 8. Diagram and examples of one-side enclosed spatial structures.

Figure 9 .
Figure 9. Diagram and examples of double-side enclosed spatial structure.

Figure 10 .
Figure 10.Diagram and example of three-side enclosed spatial structures.

Figure 11 .
Figure 11.Diagram and example of gently sloping structures obliquely crossing contour lines.

Figure 12 .
Figure 12.Diagram and examples of steeply sloping structures perpendicular to contour lines.

Figure 13 .
Figure 13.Distribution of different kinds of linear walking spaces in Yangchan village.

Figure 14 .
Figure 14.Diagram and examples of gap spaces with a continuous interface.

Figure 15 .
Figure 15.Diagram and example of top-enclosed terrace spaces.

Figure 17 .
Figure 17.Spaces promoted by local activities and communication.

Figure 18 .
Figure 18.Emotional semantic analysis results of specific spatial types in Yangchan Village.

Figure 19 .
Figure 19.Emotional semantic analysis results of characteristics of each spatial type in Yangchan Village.

Table 1 .
The frequency of text associated with different space characteristics of Yangchan.