Research On Urban Road Network Generation Of L-System Based On Conditional Constraints

The urban road network is the basic skeleton that constitutes the layout of urban land and is responsible for various functions such as transportation,and has a long-term impact on the construction and development of cities.Combining computer technology and urban planning is one of the hot topics.Urban environment modeling is the result of the combination of computer technology and urban planning.One of the important contents is the automatic generation of urban road network.The research on the automatic generation of urban road network has been favored by many scholars because of its high efficiency and low cost.At present,the research is broadly divided into two categories:using spatial information technology to extract the information of urban road network and reproduce it on the computer,and generating a virtual urban road network through the knowledge of computer graphics.In this paper,the main study content is generating a virtual plane urban road network through the combination of computer graphics knowledge and planning rules.In most of the previous studies,more considerations about the external environment are given to the constraints on the generation of the urban road.The evaluation of the result is mainly from the geometrical morphology of road,and lack of the considerations about the land use planning and indexes of road planning.This study combines road network planning and land use planning to generate an urban tertiary road network using the L-system.In the study,starting from the urban functional zones of land use,such as the residential areas,commercial areas and industrial areas,combining L-system,road forms and planning indexes,controlling the generation of urban road according to the characteristics of road network in functional zones,the index of distance between roads and external environmental constraints such as the borders,green land,rivers.In addition,optimizing the result.Finally,the index of road network density was used to evaluate the result.According to the tertiary road network density in functional zones of result,compared with recommended values,the tertiary road network density in residential areas are within the range,the tertiary road network density in parts of commercial areas are slightly higher than the recommended value,the tertiary road network density in industrial area is within the range.Overall,the result basically meets the requirements in urban planning in general.The generation of urban tertiary road network in this study,not to reproduce the road network in real cities,but to use it as a preliminary discussion of related interdisciplinary subjects,providing a reference for traditional road planning and design from a new perspective.