亚像元制图适应性分析与评价——以天津市津南区和北京市海淀区土地覆被制图为例

亚像元制图作为一种降尺度分类方法,可利用低分辨率影像获取高分辨率分类图。本文旨在探讨亚像元制图的降尺度分类结果与高分辨率影像分类精度和分类特征上的一致性。实验以天津市津南区和北京市海淀区为研究区,分别对中空间分辨率影像（TM或HJ）进行亚像元制图和对高空间分辨率影像（ALOS或ZY）进行硬分类得到相同空间分辨率的分类结果,从绝对精度、相对精度、空间结构和空间格局上,对2幅分类结果进行分析和评价。实验结果显示：（1）分类精度上,TM和HJ影像的亚像元制图结果,以地面验证样本为参考的绝对总体精度分别为84%和82%,以高分辨率影像（ALOS和ZY影像）硬分类结果,为参考的相对总体精度分别为82%和77%;（2）分类特征上,中空间分辨率影像亚像元制图结果的空间相关性较强、斑块数量较少、聚集度较高,但与高分辨率影像分类结果的总体结构相似,各类别的面积比例基本一致。因此,亚像元制图结果在分类精度和分类特征上与高空间分辨率影像分类结果具有较强的一致性,在缺少高分辨率土地覆被制图时,可将亚像元制图获取的降尺度分类图作为替代数据。

Reliability Analysis and Assessment of Sub-Pixel Mapping: A Case Study with Landsat-5Image and HJ-1A Image Based on VBSPM

Some high-resolution land cover maps are not free or available for direct use due to its economic value, the impact of weather or its confidentiality. As a downscaling classification method, sub-pixel mapping (SPM) can produce classification data with spatial resolutions finer than the original input data. We aim to explore the consistency between SPM results and classification data extracted from high-resolution remote sensing images on their accuracy and spatial characteristics. Two experiments were performed: one is in Jinnan District, Tianjin City with Landsat-5 TM image, and the other is in Haidian District, Beijing City with HJ image. Results show that the overall absolute accuracies of SPM results produced by TM and HJ images are 84% and 82% respectively. The overall relative accuracies of Landsat-5 and HJ SPM results were 82% and 77% by taking high-resolution classifications as reference. Furthermore, the overall structures and proportions based on the results using the proposed method are similar with high-resolution classifications. Therefore, with the absence of high-resolution land cover map, results generated by SPM could provide an alternative for land cover data source.