关键词: 游程编码, 栅格数据, 叠置分析

Abstract: Aiming at the low computation efficiency and storage insufficiency of direct-encoded raster data，a new data structure on the basis of run-length encoding has been proposed to optimize the algebraic operations.The realization of “intersection” is introduced；moreover，all kinds of algebraic operations on the run-length’s attribute are performed during the realization process.Adopting this“intersection” operation to implement polygon overlay，the steps are as follows：firstly，convert the polygons on two different layers into run-length sets，and then intersect the run-length set of the base layer with the run-lengths of the adding layer；afterwards，extract the required run-length units according to different overlay modes；finally，vectiorize the run-lengths into polygons.

Key words: run-length encoding, raster data, overlay analysis