The Research And Implementation On The Improved Multi-layer Grid Spatial Index

In recent years, the Geographic Information System (GIS) has made greatprogress and has been widely used in public administration, scientific research andbusiness. It plays a more important role to store, access, express and evaluate massivespatial data in information system. Relational database can store the data of geo-object,but it does not operate efficiently to obtain geo-object, due to the incompatiblenessbetween the multi-dimensional property of geo-data and the normal index, whichleads to the introduction of spatial index. With the development of GIS, spatial index technology becomes a focus field. Itis also one of the most difficult problems that always puzzle GIS researchers. How todesign proper spatial index structure is the most realistic, pressing and leading scopein GIS field. This paper tries to give some solutions on the problem. Spatial index is a key issue in massive spatial data processing. After reviewingthe development of spatial index technologies, this paper analyses the typical andefficient spatial index technologies such as grid files, quad-tree and R-tree in detailaccording to their regions whether relate to the character of geo-object's distributingor not,. This paper investigates the simple, high-efficient grid files and multi-layers gridby analyzing and comparing various kinds of spatial index technologies. Somecreative theories and relevant algorithms will be put forward such as first layer gridauto-selection algorithm based on normal distribute, multi-layers rotate coding,single-layer grid files, in-out-block algorithm to improve the performance of query. Under the instruction of these methods, this paper has designed and implementedthe improved multi-layer grid spatial index and their prototype system, which basedon the system of SircGIS.NET. We discuss and analyze the performance of the improved multi-layer grid spatialindex by real data test. This paper makes sure that the spatial index technology isfeasible and its performance is certifiable by the way of theoretic analysis and runningtest.,so the conclusion of this paper has a far-reaching academic and practical value,and can be use to guide the research and development on spatial index technology. The ending of this paper is the summary of our research results and prospect ofworking further.