利用天宫一号和Landsat7对地观测数据的森林变化检测

由于自然演替和一些干扰因素的影响,森林覆盖处在不断的变化中.结合云南省西双版纳地区的天宫一号高光谱数据以及Landsat影像,研究了热带森林覆盖制图与变化检测的自动化识别方法.首先分析了每景影像中红光波段的光谱属性,依据直方图提取出纯净森林像元,然后计算影像中各像元与纯净森林像元之间的光谱相似性,从而得到森林指数并以此为依据提取出每景影像对应的森林覆盖图,将多期的森林覆盖专题图进行叠加分析即可得到森林变化专题图.结果表明:(1)使用天宫一号高光谱影像可以进行森林覆盖自动化提取,生成的森林覆盖图合理地反映了森林分布状况;(2)与多期遥感影像结合进行森林变化信息提取,提取结果很好地体现了森林减少和森林恢复情况,对新恢复的未郁闭森林也可以进行有效检测.

Forest change detection using Tiangong-1 and Landsat 7 earth observation data

Tropical forest plays an important role in sustainable development, biodiversity conservation, and offers many environmental benefits, including essential ecosystem services such as climate change mitigation and adaptation. Deforestation is one of the main problems in tropical area. In this paper, we used hyperspectral data from Tiangong-1 space station platform and historical Landsat 7 ETM+ data to map forest coverage and detect forest changes in the tropical forests of Xishuangbanna, Yunnan province, China. First, pure forest pixels were extracted according to the characteristic in the histogram of red band. Then spectral similarity was calculated for each pixel with these pure forest pixels. This similarity index was used to generate forest coverage map. Then a forest change map was generated using these multi-temporal coverage maps. After evaluated with field survey data, the results showed that:(1) The hyperspectral data from Tiangong-1 can be used to map forest coverage effectively. The forest distribution pattern agreed well with ground survey data.(2) With the aid of historical forest coverage map, the forest changes can be detected. The deforestation and reforestation patches were characterized well. The recent reforestation stands in low canopy density level can also be detected.