Probe Into The Theory And Practice Of Four-Dimensional City

The four-dimensional urban space in this article refers to present temporal and spatial relations caused by the history accumulation. As the metaphor of "container" in <The City in History:Its Origins, Its Transformations, and Its prospects>, which is written by Lewis Mumford says:"City was a special structure since the historical origins, it is designed to store and spread the fruits of human civilization." Saving is spatial attribute and the extensive existence of history accumulation in three-dimensional concept. Circulation is temporal attribute and the durative existence of history accumulation in four-dimensional concept.First of all, based on the social essential characteristics of urban space, this article proposes the conception of four-dimensional cities-cities that can show their past or history in visible urban space. The study starts from the relationship of new elements and old ones in urban space, sums up the external morphology of four-dimensional city, and then transforms it into historical context of the time attribute.Secondly, the study of four-dimensional cities includes "spatial time" and "chronological space" two reverse processes:When studying space on the time axis, according to the tags and projection of time units on space, the evolution of four-dimensional cities takes place in three time periods:Short-term evolution based on historical "events", finds a special time milestone in urban space; Mid-term evolution based on historical "elements", looks for the common features of urban space in a certain period; Long-term evolution based on historical "environment", reveals the ultimate factors that affect the rise and fall or overall landscape of a city.When studying time on the space axis, according to the attenuation and alternation of spatial elements in time dimension, the recognition of four-dimensional cities develops in two levels:the historical pattern is directed against the integrity of "historical urban area", with which we learn conversion rules and the mode of existence, and recognizes those historical pattern prototypes that evolves through time; historical texture is directed against the authenticity of "historical district", with which we study laws of internal attenuation and ways of external intervention, and distinguish those historical texture prototypes that blurs through time.Thirdly, the theoretical knowledge is put into urban planning practices:The first case is an application of historical pattern integration planning, by identifying and reconstructing historic centers, historical axes and historical edges, to unify meaningful historical elements that loses its vitality because of spatial fracture, thus to provide an overall plan for historical urban area conservation; The second case is an application of historical district restoration planning. In accordance with the prototype analysis---type identification idea and from the perspective of historic evolution progress, it provides an "authentic" design method for the historic district. The third case is an application of historic area renewal design. In accordance with historic scale---modern function idea and from the perspective of historic elements innovation, it provides an "adaptable" design method for the historic area.Based on a large number of cases, this study establishes a systematic theoretical framework using urban space as a carrier. By adopting interdisciplinary research methods, environmental landscape design studies in traditional design arts are extended globally from micro to macro, from space to time, from built-up environment to cultural environment, which broadens the research vision and enriches the content of the subject.