基于多时相高分四号影像的雪盖范围提取

积雪覆盖监测是地球科学研究的基础，对于研究全球气候变化，开展防灾减灾救灾等工作都有重要的意义.高分四号卫星是我国高分辨率对地观测系统重大专项中唯一一颗民用高轨卫星，也是世界上首颗静止轨道高分辨率光学成像卫星，其机动灵活、高频次观测能力在积雪遥感业务化监测中具有广阔的应用前景.该文利用高分四号卫星多谱段、高时效、大幅宽和中分辨率等成像优势，紧密结合积雪和移动云层在多时相图像上的反射特点，提出了基于多时相高分四号卫星数据的积雪覆盖范围提取方法.首先对高分四号卫星全色图像进行二值化分割以消除低反射目标的影响；然后对多时相云雪覆盖区域进行合成来剔除移动云层的干扰；在此基础上，利用云、雪在多时相近红外图像上反射值变化的差异性，通过对多时相高分四号卫星近红外图像的最小值合成和阈值分割精细化地提取积雪覆盖范围，进一步去除变化云层的影响.以新疆中西部为试验区，通过与基于HJ-1B卫星的积雪覆盖结果比较，实验表明：两类数据提取的积雪空间分布具有较好的趋势一致性，高分四号卫星影像监测积雪范围更广，总体精度达92.19%，高于HJ-1B卫星图像的89.84%；但受空间分辨率和“不变云层”的影响，基于高分四号卫星影像的积雪识别精度为85.16%，低于基于HJ-1B卫星图像的识别精度94.53%.

A snow cover range extraction algorithm based on multi-temporal GF-4 satellite data

Snow cover monitoring is the foundation of earth science research， which has important significance for studies， such as global climate change， disaster prevention and disaster relief work. Gf-4 satellite is the only civil high orbit satellite in national high resolution earth observation system major project， and it is also the world's first geostationary orbit high resolution optical imaging satellite， which has broad application prospects in the snow remote sensing monitoring with its flexible and high frequency observation ability. In this paper， a method of snow cover range extraction is proposed based on multi temporal GF-4 satellite images. Using the advantage of GF-4 satellite such as multi spectrum， high efficiency， large swath and mid-resolution imaging， and combining reflection characteristics of snow and moving clouds in multi-temporal images， this method uses three main steps to extract the snow cover range. First， panchromatic images are processed by binarization segmentation to eliminate influence of low reflection targets. Then， the multi-temporal cloud and snow coverage information are synthesized to remove influence of moving clouds. On the basis of the above， by using the difference of the reflection value change of the cloud and snow in multi-temporal near infrared images， the multi-temporal minimum value synthesis and threshold segmentation of GF-4 satellite infrared images are carried out to refine snow cover range， which can further remove the influence of changing cloud. Taking the central and western regions of Xinjiang as experimental regions， the conclusion are drawn as follows through comparing the results of snow cover based on HJ-1B satellite. The spatial distribution trend of snow cover using multi-temporal GF-4 satellite data is consistent with that using HJ-1B satellite data. The snow cover monitoring region using GF-4 satellite is more extensive， and the overall accuracy of information extraction using GF-4 satellite images is 92.19%， which is higher than that of 89.84% using HJ-1B satellite images. However， due to the impact of the spatial resolution and the "constant cloud"， the snow recognition accuracy using GF-4 satellite images is 85.16%， which is lower than that of 94.53% using HJ-1B satellite images.