利用景观格局指数的空间分辨率对水域面积提取影响的分析

Influence of Landscape Pattern Index on the Area Extracted from ETM^+ and MODIS

对8个不同地区对应的同一时间的ETM+数据和MODIS数据,利用谱间关系法得到30 m和250 m分辨率具有不同景观格局分布的水体专题图,研究分辨率对不同景观格局分布的水体提取的影响。通过比较发现,区域内水体边缘密度很小时,ETM+和MODIS提取结果的误差很小;当区域内水体边缘密度很大时,ETM+和MODIS提取结果的误差相应就变大。通过引入景观格局指数与两种分辨率的提取结果进行回归分析发现,对于不破碎区域的水体,MODIS和ETM+可以得到相近的精度;而对于中度破碎的水体,引入景观格局指数信息能显著地提高中度破碎水体的精度;但对于高度破碎的水体,通过引入景观格局指数信息的多元回归几乎不能提高精度。

The water body maps of different landscape pattern with 30m and 250m spatial resolution were derived from 8 MODIS scenes and Landsat ETM＋ scenes at the same time in order to study the impact of resolution on the water body extraction with different spatial patterns.It is found that the error is small as edge density of the region is low while the error is large as edge density of the region is high.The study area was divided into three regions with different fragmental level according to edge density of the water body.Considering ETM＋ water maps as reference,the MODIS water maps overestimate the areas of less fragmental and more fragmental,and underestimate the areas of the most fragmental.As for less fragmental water body,MODIS data can get nearly the same accuracy comparing with the ETM＋ data.Landscape metrics can improve MODIS area estimates only for more fragmental water,as showed by higher values of the coefficient of determination for multiple than for simple regression.But for the most fragmental water body,the accuracy can hardly be improved by introducing landscape pattern indices.