顾及时点特征的水体提取成果空间修正方法

Research on the geospatial correction method of water extracting products considering the characteristics of time points

水体提取具有时点效应的特点,针对陆地水体季节性变化明显的客观现状,提出一种水体成果地理空间修正方法。利用高时间分辨率遥感影像开展水体信息提取,保证水体现势性满足标准时点要求;然后,将此结果作为先验知识,基于精细格网数字高程模型(digital elevation model,DEM)数据,利用水体种子点区域生长,提取精细化的水体结果,即将成果优化至高空间分辨率水平,保证水体成果满足精度要求,从而实现水体成果的地理空间修正。以第一次全国地理国情普查地表覆盖水体成果为研究实例,获取了研究区满足标准时点要求的15 m空间分辨率的Landsat8影像,基于归一化差异水体指数(normalized difference water index,NDWI)提取水体分布状况,采用2m格网DEM数据实现了精度优化。结果显示,研究区水体成果地理空间范围相对于影像源时相修正了17.97%,空间分辨率转换带来的水体成果地理空间范围优化率为1.51%。研究表明该方法能够在影像接边各方时相不满足标准时点要求的情况下,为基于遥感技术的水体信息提取提供一种顾及时点特征的成果地理空间修正方法,具有一定的实际应用价值。

The water extracting has the characteristics of time point effects.In view of the objective status of seasonal variation of land water,a method of geospatial correction for water extracting products is proposed.Firstly,the water land cover information is extracted based on high time resolution remote sensing image to ensure that the timeliness meets the standard time point.Then the result is used as a prior knowledge,and the refined water land cover information is extracted based on fine grid DEM data by using region growing algorithm of water seeds,whose accuracy is optimized to the high spatial resolution level and can meet the requirement.On such a basis,it achieves geospatial correction of water extracting products.With the first national geographic conditions census as an example,the Landsat 8 images of 15 m spatial resolution were obtained to meet the standard time point of the study area.The water land cover distribution was extracted based on the NDWI index,and the 2 m grid DEM data were used to optimize the precision.The results show that the geographical spatial range of the study area was corrected by 17.97% compared with the image source's scanning time,and geographical spatial range was optimized by 1.56% caused by the spatial resolution conversion.The research shows that this method can provide a reference for the geospatial correction in the water extraction based on remote sensing technology,and has certain practical application value in the case that the images do not meet the requirements of the standard time point.