The great goal of Chinese National Rejuvenation was officially put forward at the 19th National Congress of the Communist Party of China in 2017 . Since then, China has paid more attention than ever before to the traditional settlements like “Famous Historic-Cultural Villages/Towns” and “China Traditional Villages” (designated and issued by China government) because they are rich in excellent traditional cultural heritage, such as ancient architectural technologies, ancient arts , planning concepts, and man-land relationship philosophy. At present, in the past decades, many research findings on key issues have been published, such as preservation [3, 4], eco-environment , architecture  and tourism value , etc. To a certain extent, these studies have helped to support the social strategies of China government, such as “Rural Revitalization”  and “New Urbanization” [9, 10].
However, through the current literature, there is a lack of results on the use of semiotic principles and methods to understand the geographic characteristics of cultural landscapes of traditional settlements. This directly makes it difficult to capture the holistic features of traditional settlements and establish a corresponding research framework from a scientific perspective.
As we all know, symbols play an important role in understanding the socio-cultural factors and as basic media for exchanging and transmitting information. Semiology provides the theoretical foundation to explore social cultures . For example, we can use graphic variables  to establish a semiotic mechanism to improve the wisdom manufacturing systems , or semiotic methods for human-computer interaction , or icon design for engineering [15, 16]. This strongly hints that people can understand the socio-cultural meanings carried by cultural factors of traditional settlements from a perspective of semiotics.
Carl O. Sauer proposed the concept of cultural landscape in 1925. People have been attempting to address the evolution characteristics of regional cultures from different perspectives since then, such as “sequential occupation”  and “Morphogenesis” . And now, some scholars elucidate the core cultural features of different settlements through a combination of quantitative methods and image . For example, Wang Di  established a polar function to determine the relationships among dwelling areas, directions, and distances. However, current research can’t still address the geographical features of cultural landscapes in depth. It therefore is of paramount significance to establish a new method to analyze the cultural features of traditional settlements from a semiotic perspective.
The evolution of history and culture shows that spatial information has strategic value for human society . In fact, this promotes the development of maps, which are considered as the third language of humans since it can help people describe, exchange, and transmit spatial information. People have made meaningful progress in many areas, such as development and evolution of the map symbols , map symbol standardizing , characteristics of information transmission , and representation models . For example, He HW  put forward a new design method for map symbols through a combination of QR-code. In addition, people also made fruitful findings on the linguistic features, structures and constraint conversion into map symbols. This effectively promotes the implementation of automatic generation  and dynamic designs of map symbols.
Map symbols represent the semantic properties and features of geographical objects. They are also treated as media for communicating, transmitting, exchanging, and expressing spatial information . Map symbols are the visual symbolic system and are akin to human natural language. From the perspective of semiotics, map symbols are an effective communication tool for expressing spatial information and geographical phenomena or expressing the development and evolutionary features of geographical systems. Map symbols can support the interpretation of cultural landscape features of traditional settlements.
It should be noted that traditional settlements are the civilization results of human activities and behaviors attached to natural landscapes. In part, traditional settlements have the attributes of natural landscapes. For example, the rural landscape including traditional rural settlements provides an important platform for integrating biological and cultural diversity for human well-being . At the same time, traditional settlements are rich in historic and social information. Traditional settlements therefore are very special geographical entities. This challenges people to examine the socio-cultural properties and historic cultural value of traditional settlements through the perspective of spatial information. So, with the support of principles of map symbols and visual symbol language, people can fully understand the geographic features of traditional settlements. This is also in line with the way of human thinking and understanding.
Liu PL first proposed the concept of cultural landscape genes of traditional settlements (CLGTS) in 2003 . CLGTS is founded on cultural gene theory and biological analysis methods to understand the core characteristics of the cultural landscape of Chinese traditional settlements from a geographic perspective. To fully understand the geographic features of traditional settlements, with the support of bio-informatics and geo-information Tupu , CLGTS is mainly committed to determining the most outstanding cultural factors of traditional settlements in China and establishing a scientific framework of cultural landscape genome maps . CLGTS is widely used to solve the issues of traditional settlement landscapes in China, mainly covering the identification and regionalization of cultural genes [32–34], understanding of architectural features, and supports the tourism development .
However, at present, some scientific issues of CLGTS, such as physical shape, appearance, spatial structure, and expression method, have not been thoroughly explored. The root of the former issues lies in the lack of using relevant principles and methods of semiotics to explore the natural characteristics of cultural landscape genes. This work attempts to explore the symbolization method of CLGTS from the perspective of semiotics. According to the core characteristics of CLGTS, this work is devoted to exploring the key issues of CLGTS symbols, such as symbol features, classification methods, and corresponding symbolization methods. One aim is to provide theoretical support for establishing the symbol application of CLGTS. We hope that this work can help to further frame the theoretical system of CLGTS and promote the use of CLGTS in a wide range of application domains.