总磷(TP)、悬浮物浓度(SS)、浊度(TUB)3种水质参数可以直接通过遥感反演得到,常用于评价区域水环境的污染状况.以浙江农林大学东湖为研究对像,使用无人机携带多光谱传感器(Mica Sense Red Edge)获取多光谱影像,进而提取16个光谱参数,分...总磷(TP)、悬浮物浓度(SS)、浊度(TUB)3种水质参数可以直接通过遥感反演得到,常用于评价区域水环境的污染状况.以浙江农林大学东湖为研究对像,使用无人机携带多光谱传感器(Mica Sense Red Edge)获取多光谱影像,进而提取16个光谱参数,分别构建东湖水域TP、SS、TUB的反演模型.结果表明:光谱参数V5(NIR 0.770～0.890μm)与TP、SS相关性显著(r分别为0.470、-0.537,p<0.05),V4(0.670～0.760μm)与TUB相关性显著(r=0.486,p<0.05).在建立的TP反演模型中,指数函数模型精度最高,决定系数R^2为0.7829;在建立的SS、TUB反演模型中,多项式函数模型精度最高,决定系数R^2分别为0.7503、0.7334.经检验,TP、SS、TUB模型估测值与实测值线性拟合曲线的决定系数R^2分别为0.7374、0.8978、0.6726,满足水质要素反演的精度要求.最后利用建立的模型,结合多光谱影像数据,建立了东湖水域各参数的空间分布图,实现了水质参数的可视化,可为小微水域的污染防治提供技术支撑.展开更多
Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorith...Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorithm, e.g., simplex, GA can locate the global optimized solution instead of local ones. As an independent model algorithm, when combined with B-splines, GA gives consistent results with Chahine and Phillip-Twomey-NNLS algorithms. Numerical simulations also show that GA has high stability and good resistance to relatively higher error levels. For a population size of 50 in the present paper, the feasible ranges for genetic operators pc and pm are found to be [0.01, 0.5] and [0.01, 0.15], respectively, and the generation number Gen_Max should be larger than 250.展开更多
通过无人机多光谱影像反演农作物理化参数、动态监测作物长势是精准农业发展的重要方向。然而,由于无人机影像多具有较高的空间分辨率,地面采样点与影像上对应像素的空间范围往往不匹配,导致所构建的反演模型精度降低。为确定利用无人...通过无人机多光谱影像反演农作物理化参数、动态监测作物长势是精准农业发展的重要方向。然而,由于无人机影像多具有较高的空间分辨率,地面采样点与影像上对应像素的空间范围往往不匹配,导致所构建的反演模型精度降低。为确定利用无人机多光谱影像反演水稻叶绿素含量的最优空间窗口,该研究分别采集水稻孕穗期、抽穗期和成熟期多光谱影像,以不同大小和形状的空间窗口对影像进行处理并计算多种植被指数,将不同窗口处理的植被指数与地面实测SPAD(soil and plant analyzer development)值进行相关性分析,将相关性最高的一组植被指数所对应的空间窗口确定为最优空间窗口,并以该组植被指数与地面实测SPAD值为依据,分别构建支持向量机、随机森林、极限学习机、广义线性模型和多元逐步回归模型,分析各模型在水稻各生育期对SPAD值的反演精度。结果表明:经过空间窗口处理后各植被指数与SPAD值间的相关系数与处理前相比均有较大提升,圆形空间窗口下各生育期的最优窗口半径分别为35、25、25个像素,方形空间窗口下各生育期的最优窗口边长分别为71、41、61个像素,方形窗口处理效果与圆形窗口近似;利用支持向量机模型反演水稻SPAD值的效果最优,且在孕穗期反演精度最高,决定系数为0.718,均方根误差为1.849,平均绝对误差为1.465。研究结果可为其他作物理化参数反演的空间窗口选择提供参考,为无人机利用多光谱监测作物长势、发展精准农业提供技术支持。展开更多
In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond th...In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system.The method is demonstrated with optoacoustic measurement obtained from six-day-old mice,imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration.Wefind that estimates of the unknown point spread function,achieved by blind deconvolution,improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.展开更多
文摘总磷(TP)、悬浮物浓度(SS)、浊度(TUB)3种水质参数可以直接通过遥感反演得到,常用于评价区域水环境的污染状况.以浙江农林大学东湖为研究对像,使用无人机携带多光谱传感器(Mica Sense Red Edge)获取多光谱影像,进而提取16个光谱参数,分别构建东湖水域TP、SS、TUB的反演模型.结果表明:光谱参数V5(NIR 0.770～0.890μm)与TP、SS相关性显著(r分别为0.470、-0.537,p<0.05),V4(0.670～0.760μm)与TUB相关性显著(r=0.486,p<0.05).在建立的TP反演模型中,指数函数模型精度最高,决定系数R^2为0.7829;在建立的SS、TUB反演模型中,多项式函数模型精度最高,决定系数R^2分别为0.7503、0.7334.经检验,TP、SS、TUB模型估测值与实测值线性拟合曲线的决定系数R^2分别为0.7374、0.8978、0.6726,满足水质要素反演的精度要求.最后利用建立的模型,结合多光谱影像数据,建立了东湖水域各参数的空间分布图,实现了水质参数的可视化,可为小微水域的污染防治提供技术支撑.
文摘Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorithm, e.g., simplex, GA can locate the global optimized solution instead of local ones. As an independent model algorithm, when combined with B-splines, GA gives consistent results with Chahine and Phillip-Twomey-NNLS algorithms. Numerical simulations also show that GA has high stability and good resistance to relatively higher error levels. For a population size of 50 in the present paper, the feasible ranges for genetic operators pc and pm are found to be [0.01, 0.5] and [0.01, 0.15], respectively, and the generation number Gen_Max should be larger than 250.
文摘通过无人机多光谱影像反演农作物理化参数、动态监测作物长势是精准农业发展的重要方向。然而,由于无人机影像多具有较高的空间分辨率,地面采样点与影像上对应像素的空间范围往往不匹配,导致所构建的反演模型精度降低。为确定利用无人机多光谱影像反演水稻叶绿素含量的最优空间窗口,该研究分别采集水稻孕穗期、抽穗期和成熟期多光谱影像,以不同大小和形状的空间窗口对影像进行处理并计算多种植被指数,将不同窗口处理的植被指数与地面实测SPAD(soil and plant analyzer development)值进行相关性分析,将相关性最高的一组植被指数所对应的空间窗口确定为最优空间窗口,并以该组植被指数与地面实测SPAD值为依据,分别构建支持向量机、随机森林、极限学习机、广义线性模型和多元逐步回归模型,分析各模型在水稻各生育期对SPAD值的反演精度。结果表明:经过空间窗口处理后各植被指数与SPAD值间的相关系数与处理前相比均有较大提升,圆形空间窗口下各生育期的最优窗口半径分别为35、25、25个像素,方形空间窗口下各生育期的最优窗口边长分别为71、41、61个像素,方形窗口处理效果与圆形窗口近似;利用支持向量机模型反演水稻SPAD值的效果最优,且在孕穗期反演精度最高,决定系数为0.718,均方根误差为1.849,平均绝对误差为1.465。研究结果可为其他作物理化参数反演的空间窗口选择提供参考,为无人机利用多光谱监测作物长势、发展精准农业提供技术支持。
文摘In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system.The method is demonstrated with optoacoustic measurement obtained from six-day-old mice,imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration.Wefind that estimates of the unknown point spread function,achieved by blind deconvolution,improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.
