Research on Urban Expansion Methods Based on Lacunarity Index

The problem of urban expansion is an important part of urban development, the domestic research methods were summarized and analyzed. The study found that existing methods can be divided into exponential changes, land use changes and monitoring simulations. However, the research results of existing methods are homogenized. In this study, the gap index model was established and Kunming and Yuxi were taken as examples to systematically introduce the gap index to calculate urban expansion. The study found that the global gap index can better describe the urban expansion characteristics and can explain the heterogeneity between urban land use by scale shifting; The local clearance index can not only describe the urban expansion characteristics, but also analyze the urban expansion direction and expansion trend in detail to describe the spatial pattern change of urban expansion. The application of the gap index in urban expansion has a very good reference for future urban expansion research.