Researches on the Multi-Grids Land Resources Data Structure
摘要
The traditional land-use statistics based on districts can not represent the spatial differences of land use structure entirely.At first,the paper extends the algorithm of Statistical Information Grid-Based(STING) and then puts forward a kind of multi-grids land resources data structure according to the spatial difference of the regional land use structure.It's theory and method can be generalized as follows:Because different land use researches and applications have different data requests,the land spatial data and other natural environment/socioeconomic data should be mutually matched conveniently.So according to a certain method the land resources data space needs to be divided non-uniformly into more layers which can be called multi-grids land data structure to satisfy the distribution of data items.Namely the region with crowded data(land use structure is fine) should contain the massive small grids,but the region with sparse data(land use structure is extensive) only includes a few big grids.Through analysis the landscape multiplicity is selected as a quantitative index for building such a multi-grids land data structure and the expression of landscape multiple index is:H=-∑(S_i/∑S_i) ×log_2(S_i/∑S_i)(i=1,2,…,m)where H is landscape multiple;m is the number of the type of landscape in the region;and S_i is the area of one land use/cover type.RS images contain rich land use/cover information,so the land classification results using RS images can be applied to figure out the value of 'H' index.In the paper the experiment data are TM images of Wuhan district(1998-10),with an overall precision of land use/cover classification result being 89% and KP value 0.87.Taking the entire experimental land data space as the root point the quad tree division is done.In advance a threshold named N of 'H' should be decided(for example taking one half of the H_max as a threshold) to judge whether a grid point continues to be divided or not.If the 'H' value of a grid point is smal