Sentinel-1/2影像在兰州北山削山造地范围识别中的应用

城市空间发展易受地形所限,削山造地能克服土地资源稀缺,成为解决城市空间拓展最为直接的途径。该方法利用遥感技术快速准确获取削山造地范围信息,对区域生态环境科学评估和新城发展规划具有十分重要的意义。本文基于GEE遥感云计算平台,利用Sentinel-1合成孔径雷达(synthetic aperture Rader,SAR)数据,采用组合升、降轨影像,在噪声滤除和多时相影像合成的基础上,计算削山造地前后后向散射强度的差值,并采用百分位阈值法结合样本数据确定阈值,提取研究区2017—2022年削山造地开挖区时空分布;然后联合SAR和光学数据的光谱特征、纹理特征和地形特征,在特征优化的基础上结合随机森林算法获取了2017—2022年逐年削山造地范围时空分布。研究结果表明:①提取的开挖区范围总体分类精度和Kappa系数分别达85%和0.83。②研究期间,发现2019年前开挖区主要集中在九州开发区、碧桂园和保利领秀山,2020年以后新增加了刘家沟、水源站等开挖区,开挖范围和强度逐渐增大。③2018年前造地规模较小,面积为2.655 km 2;2019年以后造地规模逐年增大,特别是2021年,其造地面积达12.607 km 2,占监测期间总造地面积的34.56%,2022年在原造地基础上开挖,因坡度和开挖量逐渐增大,造地面积仅2.686 km 2。本文构建的削山造地开挖区监测和造地范围提取方法可有效获取削山和造地范围快速监测与提取。

基于Sentinel-2与时序Sentinel-1 SAR特征的赣南柑橘种植区识别方法

为准确获取柑橘果园空间分布信息,实现柑橘种植结构调整、产量估算和资源管理,以赣南3个柑橘种植主产区(信丰县、安远县及寻乌县)为研究区域,针对南方地区多云多雨导致传统光学影像较为缺乏的问题,使用Sentinel系列数据和PIE-Engine平台,构建和优选了光谱特征、植被水体指数特征、红边波段特征和纹理特征,并引入时间序列Sentinel-1合成孔径雷达(SAR)数据的后向散射系数,共同探讨不同特征组合对柑橘种植园的识别提取效果,基于随机森林算法并融合Sentinel-2与时序Sentinel-1 SAR特征识别提取了赣南柑橘种植区。结果表明:5、9、11月柑橘种植园与其他地物的平均后向散射系数分离性最佳,是识别提取柑橘的关键时期;指数特征及纹理特征参与分类改善了分类效果且提高了分类精度;相较于单一SAR特征及指数、纹理特征,加入时序SAR特征的分类结果中总体精度达90.084%,Kappa系数达0.863,错分、漏分误差较小,符合实际地物分布情况,说明了时序SAR特征的可用性和实用性。本研究可为多云多雨的南方柑橘果园的识别提取提供参考。

Axillary Sentinel Lymph Node Biopsy for Breast Cancer and Melanoma Patients after Previous Axillary Surgery: A Systematic Review

Objective: Sentinel lymph node biopsy (SLNB) is a validated staging technique for breast carcinoma. Some women are exposed to have a second SLNB due to breast cancer recurrence or a second neoplasia (breast or other). Due to modified anatomy, it has been claimed that previous axillary surgery represents a contra-indication to SLNB. Our objective was to analyse the literature to assess if a second SLNB is to be recommended or not. Methods: For the present study, we performed a review of all published data during the last 10 years on patients with previous axilla surgery and second SLNB. Results: Our analysis shows that second SLNB is feasible in 70%. Extra-axillary SNs rate (31%) was higher after radical lymph node dissection (ALND) (60% - 84%) than after SLNB alone (14% - 65%). Follow-up and complementary ALND following negative and positive second SLNB shows that it is a reliable procedure. Conclusion: The review of literature confirms that SLNB is feasible after previous axillary dissection. Triple technique for SN mapping is the best examination to highlight modified lymphatic anatomy and shows definitively where SLNB must be performed. Surgery may be more demanding as patients may have more frequently extra-axillary SN only, like internal mammary nodes. ALND can be avoided when second SLNB harvests negative SNs. These conclusions should however be taken with caution because of the heterogeneity of publications regarding SLNB and surgical technique.

融合Sentinel-1特征参数的海冰类型监测研究

本文以Sentinel-1A为实验数据,提取加拿大西北航道部分区域的纹理特征和极化特征,采用相关分析和ReliefF法筛选出对分类具有促进作用的特征参数,将参数进行组合后输入随机森林分类器进行海冰类型的识别。通过对比不同组合特征的分类精度,得到以下结论:融合纹理特征和极化特征的分类精度高达92.01%,分类结果相较其他融合特征组合也更加平滑,加入纹理特征或极化特征使分类精度提高了2.59%——18.75,Kappa系数也相应的得到了提高。实验表明,特征融合对识别不同海冰类型有促进作用,可以弥补单一特征之间的不足,提高海冰分类的精度。

基于Sentinel数据的沅陵县针叶林可燃物载量估测研究

森林可燃物是引发森林火灾的重要因素之一,准确估测森林可燃物载量对于制定火灾防控策略、提高火灾预警能力以及保护生态环境具有重要意义。以湖南省沅陵县Senitnel-1A和Sentinel-2A影像为数据源,通过提取多源数据的不同类型遥感因子,结合地面调查获取的样地可燃物载量信息,采用前向特征筛选法和4种机器学习模型[多元线性回归(multiple linear regression,MLR)、k最近邻(k-nearest neighbor,kNN)、支持向量机回归(support vector regression,SVR)、随机森林(random forest,RF)]构建了针叶林可燃物载量反演模型,并对研究区内针叶林可燃物载量进行反演。结果表明:①基于Sentinel-1A数据提取的VH极化后向散射系数与针叶林可燃物载量有较高的相关性;②相比于单一数据源,联合Sentinel-1A和Sentinel-2A数据可显著提高针叶林可燃物载量估测精度,最优模型R^(2)分别提高了0.19、0.29,rRMSE分别降低4.66、6.94个百分点,RMSE分别降低了6.13、9.13 t/hm^(2),平均rRMSE分别降低了5.17、5.75个百分点,最优模型为SVR模型,其R^(2)=0.5,rRMSE=27.71,RMSE=36.47 t/hm^(2)。Sentinel-1A数据的加入有利于针叶林可燃物载量估测精度的提升。

基于Sentinel2A影像的干旱区土壤盐渍化监测研究

以渭干河-库车河三角洲绿洲为例,在5种盐分光谱指数(NDSI、SI、SI1、SI2、SAVI)基础上,选择Sentinel2A多光谱影像中的3个红边波段和近红外窄波段进行扩展,提出了新的基于红边和近红外窄波段的光谱指数,用偏最小二乘回归(PLSR)方法构建土壤电导率遥感反演模型。结果表明:相对传统光谱指数,引入红边1波段(B_(5))和近红外窄波段(B_(8a))的光谱指数与土壤电导率相关性显著提高;基于Sentinel2A影像的PLSR的土壤电导率信息建模效果较好(R^(2)=0.77),模型准确、可靠。盐分反演结果表明研究区土壤盐分含量整体较高,盐渍化影响范围广泛。自绿洲内部向外围由非盐渍化向轻度-中度-重度盐渍化过渡,绿洲西部、南部轻度盐渍土分布较多,绿洲东部、东南及西南方向有重度盐渍土及极重度盐渍土分布,盐渍化程度较高。

Application value of indocyanine green fluorescence imaging in guiding sentinel lymph node biopsy diagnosis of gastric cancer: Meta-analysis

BACKGROUND Gastric cancer is a common malignant tumor of the digestive system worldwide,and its early diagnosis is crucial to improve the survival rate of patients.Indocyanine green fluorescence imaging(ICG-FI),as a new imaging technology,has shown potential application prospects in oncology surgery.The meta-analysis to study the application value of ICG-FI in the diagnosis of gastric cancer sentinel lymph node biopsy is helpful to comprehensively evaluate the clinical effect of this technology and provide more reliable guidance for clinical practice.AIM To assess the diagnostic efficacy of optical imaging in conjunction with indocya-nine green(ICG)-guided sentinel lymph node(SLN)biopsy for gastric cancer.METHODS Electronic databases such as PubMed,Embase,Medline,Web of Science,and the Cochrane Library were searched for prospective diagnostic tests of optical imaging combined with ICG-guided SLN biopsy.Stata 12.0 software was used for analysis by combining the"bivariable mixed effect model"with the"midas"command.The true positive value,false positive value,false negative value,true negative value,and other information from the included literature were extracted.A literature quality assessment map was drawn to describe the overall quality of the included literature.A forest plot was used for heterogeneity analysis,and P<0.01 was considered to indicate statistical significance.A funnel plot was used to assess publication bias,and P<0.1 was considered to indicate statistical significance.The summary receiver operating characteristic(SROC)curve was used to calculate the area under the curve(AUC)to determine the diagnostic accuracy.If there was interstudy heterogeneity(I2>50%),meta-regression analysis and subgroup analysis were performed.analysis were performed.RESULTS Optical imaging involves two methods:Near-infrared(NIR)imaging and fluorescence imaging.A combination of optical imaging and ICG-guided SLN biopsy was useful for diagnosis.The positive likelihood ratio was 30.39(95%CI:0.92-1.00),the sensitivity was 0.95(95%CI:0.82-0.99),and the specificity was 1.00(95%CI:0.92-1.00).The negative likelihood ratio was 0.05(95%CI:0.01-0.20),the diagnostic odds ratio was 225.54(95%CI:88.81-572.77),and the SROC AUC was 1.00(95%CI:The crucial values were sensitivity=0.95(95%CI:0.82-0.99)and specificity=1.00(95%CI:0.92-1.00).The Deeks method revealed that the"diagnostic odds ratio"funnel plot of SLN biopsy for gastric cancer was significantly asymmetrical(P=0.01),suggesting significant publication bias.Further meta-subgroup analysis revealed that,compared with fluorescence imaging,NIR imaging had greater sensitivity(0.98 vs 0.73).Compared with optical imaging immediately after ICG injection,optical imaging after 20 minutes obtained greater sensitivity(0.98 vs 0.70).Compared with that of patients with an average SLN detection number<4,the sensitivity of patients with a SLN detection number≥4 was greater(0.96 vs 0.68).Compared with hematoxylin-eosin(HE)staining,immunohistochemical(+HE)staining showed greater sensitivity(0.99 vs 0.84).Compared with subserous injection of ICG,submucosal injection achieved greater sensitivity(0.98 vs 0.40).Compared with 5 g/L ICG,0.5 and 0.05 g/L ICG had greater sensitivity(0.98 vs 0.83),and cT1 stage had greater sensitivity(0.96 vs 0.72)than cT2 to cT3 clinical stage.Compared with that of patients≤26,the sensitivity of patients>26 was greater(0.96 vs 0.65).Compared with the literature published before 2010,the sensitivity of the literature published after 2010 was greater(0.97 vs 0.81),and the differences were statistically significant(all P<0.05).CONCLUSION For the diagnosis of stomach cancer,optical imaging in conjunction with ICG-guided SLN biopsy is a therapeut-ically viable approach,especially for early gastric cancer.The concentration of ICG used in the SLN biopsy of gastric cancer may be too high.Moreover,NIR imaging is better than fluorescence imaging and may obtain higher sensitivity.

Clinical Study of Double Contrast-Enhanced Ultrasound Combined with Dye Method and Marker Placement to Identify and Locate Sentinel Lymph Nodes in Patients with Breast Cancer

Objective: To explore the value of percutaneous ultrasonography combined with transvenous ultrasonography for accurate localization of sentinel lymph nodes and diagnosis of metastatic lymph nodes in patients with breast cancer. Methods: 18 cases of patients with breast cancer attending the Hainan General Hospital from May 2022 to June 2024 who were proposed to undergo axillary lymph node dissection were selected, and the ultrasonographic agent was injected subcutaneously through the areola on the 1st day before the operation, and the marker localization of the manifestation of the Sentinel lymph nodes and draw the lymphatic vessel alignment for drainage on the body surface, and record the manifestation of SLN by conventional ultrasound and dual ultrasonography. At the time of surgery, intraoperative melphalan localization was used to identify the SLN, the difference between the number of ultrasound and melphalan localization was observed, and resection was performed for pathological examination to determine whether they were metastatic or not. Results: There were 8 metastatic lymph nodes and 18 non-metastatic lymph nodes among 31 SLN. A total of 62 SLN were localized by intraoperative melphalan, of which 31 were consistent with ultrasound localization and 31 were not identified by ultrasound. The diagnostic sensitivity of SLN metastasis diagnosed by transcutaneous ultrasonography was 62.50%, specificity was 91.30%, positive predictive value was 71.43%, negative predictive value 87.50%, accuracy was 83.87%, and the AUC was 0.769;the diagnostic sensitivityof transvenous ultrasonography diagnosed was 75.00%, specificity was 75.00%, and the accuracy was 83.87%, 75.00%, specificity 91.30%, positive predictive value 75.00%, negative predictive value 91.30%, accuracy 87.10%, AUC 0.832;dual ultrasonography diagnostic sensitivity 87.50%, specificity 91.30%, positive predictive value 77.78%, negative predictive value 95.45%, accuracy 90.32%. The AUC was 0.894. Conclusion: Transcutaneous ultrasonography combined with transvenous ultrasonography can accurately localize sentinel lymph nodes and improve the sensitivity and accuracy of the diagnosis of metastatic SLN.

基于Sentinel多源数据的农田地表土壤水分反演模型构建与验证

土壤水分是影响水文、生态和气候等环境过程的重要参数,而微波遥感是农田地表土壤水分测量的重要手段之一。针对微波遥感反演农田地表土壤水分受植被覆盖影响较大的问题,该文基于Sentinel-1和Sentinel-2多源遥感数据,利用Oh模型、支持向量回归(support vector regression,SVR)和广义神经网络(generalized regression neural Network,GRNN)模型对土壤水分进行定量反演,以减小植被影响,提高反演精度。结果表明:通过水云模型去除植被影响后的Oh模型反演精度有所提高。加入不同植被指数的SVR和GRNN模型的反演效果总体优于Oh模型,基于SVR模型的多特征参数组合(双极化雷达后向散射系数、海拔高度、局部入射角、修改型土壤调整植被指数)反演效果最优,其测试集相关系数和均方根误差分别达到了0.903和0.015cm^3/cm^3,为利用多源遥感数据反演农田地表土壤水分提供了参考。

基于多源Sentinel数据的县域冬小麦种植面积提取

冬小麦是我国主要的粮食作物之一,及时准确地获取冬小麦种植面积对农业政策的制定具有重要意义。以河南省扶沟县为研究区域,以多生育期Sentinel-1A和Sentinel-2A/B遥感影像为数据源,构建光谱特征、植被特征和极化特征的多生育期数据集,分析各类地物的特征曲线,采用随机森林算法对单生育期单传感器、单生育期多传感器、多生育期单传感器和多生育期多传感器的遥感影像进行精细分类,实现县域冬小麦制图。结果显示:单生育期的雷达影像无法满足制图要求,拔节期的总体精度最高,仅为62.9%,多生育期雷达影像分类精度达到81.9%,基本满足制图要求;单生育期的光学影像和融合影像在成熟期的精度最高,总体精度分别为93.4%和95.1%,Kappa系数分别为92.4%和94.8%,可以绘制较为精准的冬小麦分布图;多生育期融合影像绘制的扶沟县2019年冬小麦空间分布图,总体精度为96.8%,结果最优。研究结果表明融合的多生育期遥感影像可以为县域冬小麦种植面积的提取提供技术依据。

基于多时相Sentinel-2A的县域农作物分类

利用遥感技术精准地获取区域农作物种植结构数据,对指导农业生产、制定农业政策具有重要意义。以景泰县为研究区,以多时相Sentinel2A遥感影像为数据源,计算时序归一化植被指数(Normalized difference vegetation index,NDVI)和红边归一化植被指数(Red edge normalized vegetation index,RENDVI)及其组合特征(NDVI+RENDVI、NDVI RENDVI和NDVI&RENDVI),分析作物特征曲线,并采用随机森林法分别以5种特征参数作为分类特征对研究区农作物进行精细分类。结果表明:根据形态特征,研究区农作物特征值曲线可划分为3种类型:高值型(玉米、水稻、胡麻和马铃薯)、低值型(洋葱、大棚作物和砂田瓜果)和开口型(春小麦、春小麦秋油葵)。高值型和低值型可在7、8月影像中区分,开口型和前两种类型在5月和9月影像上的特征值有明显差异。3种类型内的作物可以通过不同时相影像区分,高值型的4种作物在9月影像上通过成熟期差异可以区分;低值型的3种作物的特征值差异在全年影像上都可以明显体现;开口型的两种作物利用9月影像可以明显区分。利用NDVI、RENDVI、NDVI+RENDVI、NDVI RENDVI和NDVI&RENDVI 5种特征分类的总体精度分别为82.14%、78.16%、81.17%、75.64%和86.20%,Kappa系数分别为0.78、0.74、0.77、0.71和0.83,总体精度和Kappa系数由大到小依次为NDVI&RENDVI、NDVI、NDVI+RENDVI、RENDVI、NDVI RENDVI,说明RENDVI辅助NDVI可以有效提高分类精度(精度较仅用NDVI提高4.06个百分点)。选择合适的时期和分类特征,利用Sentinel2A特有的红边波段数据及其较高的空间分辨率在县域农作物精细分类上具有较好的精度。

Experimental Study of Chinese Ink as a New Type of Dye Tracer in Sentinel Lymph Node Biopsy~*

Objective： To investigate the potential clinical value of Chinese ink as a tracer in dye-directed sentinel lymph node biopsy. Methods： Forty-two female rabbits were randomly divided into 7 groups. The breast drainage lymphatic vessels and nodes in axilla were exposed by surgery. Under the papillae of the second pair of breast, 0.1 mL Chinese ink dilution at concentrations of 0.1%, 1%, 10%, 50% and 100% and isosulfan blue （IB, 1.0%） were injected. The movement of ink in lymphatic chain was investigated, and the number of stained nodes and their staining and washout time ware recorded. The first stained lymph node that was followed through lymphatic drainage was identified as the sentinel lymph node （SLN）. The SLNs were dissected and prepared for histological observation 5 rain, 1 h and 2 weeks after stained. Blood samples were harvested and tested before and 2 weeks after injection. The hearts, lungs, livers and kidneys were dissected after a period of post-operation observation and sent for pathologic examination. Results： No obvious differences were observed among the staining time of SLNs and the second lymph node using ink at different concentrations （P〉0.05）. But they were obviously longer than that of IB （P〈0.05）. The mean number of nodes obtained was nearly the same （P〉0.05）. It was too light for gross visual inspection when nodes were stained by ink at the concentration of 0.1%. Nodes stained by IB faded 33.9 rain after stained. And carbon staining seemed permanent without any visible decline after 2 weeks. Carbon particles were found to be in the sinus of lymph nodes that were obtained 5 rain after stained, and then was phagocytosed by macrophages （MФ） 1 h later. The density of carbon obscured the microscopic observation of lymph nodes when they were stained using Chinese ink at concentration of higher than 20.0%. No obvious changes were investigated in blood test and vital organ pathologic examination. Conclusion： Chinese ink is potentially a novel type of dye tracer in SLN biopsy.

基于Sentinel多源数据的晋南农田地表土壤水分反演

通过遥感数据反演农田地表土壤水分,对农作物干旱、长势监测及估产有重要指导作用。以山西省闻喜县冬小麦种植区为研究区,利用水云模型去除植被影响,建立土壤直接后向散射系数与土壤含水量的关系,反演闻喜县2018年3月19日冬小麦种植区土壤水分。结果表明:协同Sentinel-1微波和Sentinel-2光学影像数据能够去除植被影响提高土壤水分反演精度,VV极化决定系数R2提高0.0914,均方根误差RMSE减少0.0895%。闻喜县中部河谷平原以及东南和西北部的台地土壤处于轻度干旱状态,西南部丘陵和东部山地土壤处于中度干旱状态。反演的土壤水分空间分布结果与地形起伏、灌溉条件和地力等级有较好的空间一致性,地形起伏低、灌溉条件良好的农田土壤水分含量高。

基于Sentinel1A双极化时序数据的甘蔗株高反演方法

甘蔗株高为甘蔗品种与土壤、气象、水文等因素的综合反映,是甘蔗长势监测与估产的重要指标。研究以华南地区气候与天气条件为基础,通过对覆盖甘蔗全生长期的23景时间序列Sentinel1A数据进行预处理、矩阵转换与CloudePottier分解,求得双极化雷达植被指数(Dual-pol radar vegetation index,DPRVI)。分析了该指数与甘蔗长势参数(株高)随甘蔗不同生长期的动态变化规律。采用4种经典的经验回归模型(线性、二次多项式、指数、对数),以分段函数形式对不同生长期的甘蔗株高进行反演,建立最佳反演模型。实验结果表明,拟合模型在分蘖期前相关性最高,二次多项式模型拟合效果最优,决定系数R^(2)与均方根误差分别达到了0.882与0.118 cm,对反演效果最好的分蘖期之前的二次函数模型进行验证,结果表明决定系数R^(2)达0.839,平均绝对偏差为7.4%,说明DPRVI反演甘蔗株高是有效的。将DPRVI与其他3种经典的反演参数进行对比,结果表明,DPRVI的性能优于其他3种参数。通过分析可得,DPRVI可以较好地反演甘蔗生长前期的株高变化,反演的株高参数可供农业管理部门参考。

基于GEE云平台的滇池湿地分类

湿地是维护滇池湖泊水质的重要屏障。快速、准确地获取滇池湿地类型分布对于其水质保护具有重要意义,然而目前关于滇池不同湿地类型的研究存在明显不足。为此,基于GEE平台的Sentinel-1和Sentinel-2影像数据对滇池湿地进行分类,分析比较不同分类特征组合应用3种机器学习方法(SVM、CART和RF)分类的性能。结果表明,RF的分类性能优于CART和SVM;其使用光谱波段、光谱指数、雷达特征、地形特征、纹理特征作为分类依据时的总体分类精度和沼泽湿地分类精度最高,总体精度为86.81%,Kappa系数为0.84%,F得分为85.83%,对木本沼泽和草本沼泽分类的F得分分别为85.71%、78.69%。

贝克休斯地层测试器RCX Sentinel在流体取样中的应用

地层原生流体可提供准确可靠的井下数据,但利用传统取样方法获取的流体含污率较高,取样量和作业耗时也不够理想,既无法满足后续分析及评价需求,还严重影响施工进度和成本.为了充分利用流体样品进行科学研究,贝克休斯公司推出了一款可在低耗时、低成本、低风险条件下获取适量高纯度样品的新型技术——RCX Sentinel.文章通过介绍RCX Sentinel仪器的组成和工作原理,并结合北海、墨西哥湾及北美等地区的应用实例,对其整体效果进行分析评价.结果表明,利用RCX Sentinel仪器进行流体取样可节约70％～80％耗时,含污率控制在1％～2％左右,总体取样质量较高,为实现储层评价与分析、生产监测及完井决策等工作提供了有力支持.

CBCT影像扫描系统与Sentinel激光扫描系统对摆位误差测量结果的比较研究

目的比较CBCT影像系统和Sentinel激光扫描系统对胸腹部肿瘤患者摆位误差测量结果的优劣。方法选取19例胸腹部肿瘤IMRT患者,放疗前行CBCT扫描,扫描的同时进行Sentinel激光扫描系统扫描并成像,得出x、y、z三个线性方向和u,v,w(绕x轴、y轴和z轴)的三个旋转方向的摆位误差值,并对两种测量结果行配对t检验。结果用CBCT每例患者摆位验证需114 s,而Sentinel仅需5 s。测量结果显示,两组数据线性误差在z轴(上下方向)存在差异(t=-4.243,P<0.05),旋转误差在v方向(绕y轴方向)上存在差异(t=5.667,P<0.05),其它方向差异不大。结论 CBCT对胸腹部肿瘤患者摆位误差的测量结果大部分优于Sentinel激光扫描系统,CBCT能对患者治疗摆位进行较为准确测量及校正,可作为治疗前的摆位校正依据。Sentinel激光扫描系统应用直观、简便、耗时短、可实时追踪,适合在患者位置校正后进行辅助监测。

基于Sentinel卫星的浑浊水体叶绿素反演对比研究——以鄱阳湖为例

Sentinel-2A卫星、Sentinel-3A卫星分别于2015年6月和2016年2月成功发射,其上搭载的MSI、OLCI传感器的空间分辨率、时间分辨率、波段设置等在内陆水体水环境遥感研究中具有较大的应用潜力.针对浑浊水体叶绿素的反演难题,以鄱阳湖为例,基于光学分区理论并结合同步实测数据,探讨了Sentinel系列卫星数据在湖泊叶绿素a遥感反演的可行性.研究表明:1)对于Sentinel-2A MSI数据,鄱阳湖北湖区以[1/Rrs(665)-1/Rrs(705)]*Rrs(740)作为反演因子构建的三波段模型拟合效果最好,决定系数R2是0.65,平均相对误差是38.53%;鄱阳湖南湖区差值模型Rrs(705)-Rrs(665)反演结果最好,R2是0.63,相对误差是39.87%.2)对于Sentinel-3A OLCI数据,鄱阳湖北湖区以[1/Rrs(665)-1/Rrs(673.75)]*Rrs(753.75)作为反演因子构建的三波段模型拟合效果最好,R2为0.65,平均相对误差为37.6%;鄱阳湖南湖区差值模型Rrs(708.75)-Rrs(665)反演结果最好,R2是0.62,平均相对误差为39.6%.3)Sentinel系列卫星的分区模型能在一定程度上解决鄱阳湖部分浑浊水体区域叶绿素反演不成功的问题,后续将研究更高精度的反演模型方法.

Sentinel双机容错系统实现方法及在铁路客票系统中的应用

Sentinel纯软件双机热备容错系统是继共享磁盘阵列双机系统后的又一重要容错系统 ,该容错系统在铁路应用日渐扩大 ,本文着重介绍该容错系统的实现方法、在铁路客票系统中的应用及常见故障检查与处理方法。

Sentinel 2A影像去云下的丘陵地区植被覆盖度反演

光学遥感影像作为一种重要的数据源,被广泛应用于植被覆盖度反演,但南方丘陵地区常年多云雾,受云雾污染,像元质量下降。受丘陵地形的限制,地块破碎化严重,加之南方丘陵植被类型多,植被光谱变化较大,这些因素造成了植被覆盖度提取的准确度降低。为了提高丘陵地区植被覆盖度反演的精度,提出一种整合光学与SAR影像的反演框架。以Sentinel1A和Sentinel 2A影像作为遥感数据源,首先利用Sentinel 1A的光谱特征去除Sentinel 2A影像上的云像元,再使用光谱归一化减弱植被的光谱变化,在此基础上将扩展线性光谱混合模型用于反演植被覆盖度。结果表明:该框架能有效恢复云污染的像元,端元和影像归一化后,降低光谱异质性,反演丘陵地区植被覆盖度的精度较高,均方根误差为0.14,相关系数为0.95,接近地表植被覆盖的真实情况。