Research on GSQL Extension Supporting Raster Data
LIU Yu, LIN Xing, QIN Shi, ZHANG Yi, WU Lun (Institute of Remote Sensing and Geographic Information Systems, Peking University, Beijng 100871)
Spatial database has become one of the dominating techniques to manage spatial data in geographical information systems, and geographic structured query language (GSQL) is the key issue of spatial database design and implementation. At present, GSQL for vector data has been widely studied. However, when considering the raster data, little research was made for their specifications on visiting and operational. Based on OpenGIS ○R , a GSQL extension named GSQL R supporting raster data is discussed in this paper. At first, some abstract data types (ADTs), including Pixel, RasterRegion and RasterCoverage, are defined. The relationships between Pixel/RasterRegion and RasterRegion/RasterCoverage are part/whole. In these definitions, data objects and operations for each ADT are described in a formalized way. Then, GSQL R syntax and some instances are presented. The GSQL R description includes three parts, i.e. data definition language (DDL), data table schema and data manipulation language (DML). The example indicates that GSQL R provides an efficient and integrated way for raster data access and operation.