For the application of the CCD camera, the most important payload on CBERS-02, the key is to provide long-term stable radiometric calibration coefficients. Although the vicarious calibration had been proved successful...For the application of the CCD camera, the most important payload on CBERS-02, the key is to provide long-term stable radiometric calibration coefficients. Although the vicarious calibration had been proved successful, it had its limitations such as test site requirement and unsuitable for historical data. Cross-calibration is one of the alternative methods, but it needs synchro surface spectrum to achieve spectral band matching factors. Our effort is to probe the influences on these factors. Simulations with a lot of surface spectrum showed that the factors changed with the viewing geometry, atmospheric condition and surface targets. However, simulating with the same viewing geometry and atmospheric condition, the spectral band matching factors of the same or similar surface targets’ spectrum acquired from different dates and different places would like to be consistent to each other within 1%―5%. Thus, the synchro measurement data can be substituted by the same or similar target from other source. Based on this method, using the MODIS as the reference, the cross-calibration was performed for CCD camera. The research demonstrated that the traditional method with single calibration site was inappropriate for CCD camera, since the offsets for its four spectral bands were not zeros. With four calibration sites, these offsets were obtained. And the camera was detected to degrade with dates based on four times of cross-calibrations.展开更多
基于液晶调谐滤光片(LCTF)的光谱相机由于体积小、功耗低、集成方便,适合多种搭载平台,同时通过光谱反射率来识别目标物,可以有效解决同色异谱的问题,在伪装识别、精细农产品产值估计等方面有很好的应用前景。比较测量法因其能有效排除...基于液晶调谐滤光片(LCTF)的光谱相机由于体积小、功耗低、集成方便,适合多种搭载平台,同时通过光谱反射率来识别目标物,可以有效解决同色异谱的问题,在伪装识别、精细农产品产值估计等方面有很好的应用前景。比较测量法因其能有效排除光照条件和场景背景条件的影响,重建效率较高,在光谱相机的光谱反射率重建中被普遍采用。比较测量法通常采用标准白板作为参考物,但实际应用中,经常会遇到目标场景空间位置不便放置标准白板的情况。针对这种情况,研究采用LCTF光谱相机采集的目标场景中亮度高的颜色作为参考的比较测量法进行目标物的光谱反射率重建来解决上述问题。实验以美国X-Rite的Gretg Macbeth Color Checker(MCC)色卡作为目标物,分别参考亮度高的五个不同色块,运用比较测量法完成红、绿、蓝三个色块的光谱反射率重建。将重建后三个色块的光谱反射率与采用台式分光光度计(X-Rite Color Eye7000A)测量的标准光谱反射比进行比较。结果显示,重建后的红、绿、蓝三个色块的光谱反射率曲线与用分光光度计测量的标准光谱反射率曲线的形状基本相似,每组曲线的均方根误差均小于0.05;重建的蓝色色块的光谱反射率以参考与其光谱反射比接近的蓝绿色重建的效果最好;重建的红色和绿色色块的光谱反射率以除白色外亮度最高的黄色为参考重建的效果最好;二者均比参考标准白板的反射率重建效果好。实验结果说明采用目标场景中亮度高目视效果明显的色块作为参考对象可被用来进行LCTF光谱相机的光谱反射率重建。该方法有效扩大了比较测量法以及液晶调谐光谱成像系统的应用效率。展开更多
The acquisition of digital regional-scale information and ecological environmental data has high requirements for structural texture,spatial res-olution,and multiple parameter categories,which is challenging to achiev...The acquisition of digital regional-scale information and ecological environmental data has high requirements for structural texture,spatial res-olution,and multiple parameter categories,which is challenging to achieve using satellite remote sensing.Considering the convenient,facilitative,and flexible characteristics of UAV(unmanned air vehicle)remote sensing tech-nology,this study selects a campus as a typical research area and uses the Pegasus D2000 equipped with a D-MSPC2000 multi-spectral camera and a CAM3000 aerial camera to acquire oblique images and multi-spectral data.Using professional software,including Context Capture,ENVI,and ArcGIS,a 3D(three-dimensional)campus model,a digital orthophoto map,and multi-spectral remote sensing map drawing are realized,and the geometric accuracy of typical feature selection is evaluated.Based on a quantitative remote sensing model,the campus ecological environment assessment is performed from the perspectives of vegetation and water body.The results presented in this study could be of great significance to the scientific management and sustainable development of regional natural resources.展开更多
The fluorescence spectra of three different dyes adsorbed on the tabular and cubic AgBr microcrystals are obtained by the picosecond time-resolved streak camera technique. The dependence of the ultrafast electron tran...The fluorescence spectra of three different dyes adsorbed on the tabular and cubic AgBr microcrystals are obtained by the picosecond time-resolved streak camera technique. The dependence of the ultrafast electron transferring from dye-aggre-gates to the conduction band of AgBr and the efficiency of spectral sensitization on different kinds of dyes with different concentrations is analyzed. Further more,the microcosmic mechanism of the sensitization process is discussed. It is found that the fluorescence decay curves are fitted very well by the double exponential func-tion,consisting of a slow component and a fast one with large amplitude. We con-sider this fast one mainly attributable to the electron transfer from dye J-aggre-gates to the conduction band of AgBr.展开更多
A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pres- sure. The experimental results showed ...A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pres- sure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be (2). Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure.展开更多
文摘For the application of the CCD camera, the most important payload on CBERS-02, the key is to provide long-term stable radiometric calibration coefficients. Although the vicarious calibration had been proved successful, it had its limitations such as test site requirement and unsuitable for historical data. Cross-calibration is one of the alternative methods, but it needs synchro surface spectrum to achieve spectral band matching factors. Our effort is to probe the influences on these factors. Simulations with a lot of surface spectrum showed that the factors changed with the viewing geometry, atmospheric condition and surface targets. However, simulating with the same viewing geometry and atmospheric condition, the spectral band matching factors of the same or similar surface targets’ spectrum acquired from different dates and different places would like to be consistent to each other within 1%―5%. Thus, the synchro measurement data can be substituted by the same or similar target from other source. Based on this method, using the MODIS as the reference, the cross-calibration was performed for CCD camera. The research demonstrated that the traditional method with single calibration site was inappropriate for CCD camera, since the offsets for its four spectral bands were not zeros. With four calibration sites, these offsets were obtained. And the camera was detected to degrade with dates based on four times of cross-calibrations.
文摘基于液晶调谐滤光片(LCTF)的光谱相机由于体积小、功耗低、集成方便,适合多种搭载平台,同时通过光谱反射率来识别目标物,可以有效解决同色异谱的问题,在伪装识别、精细农产品产值估计等方面有很好的应用前景。比较测量法因其能有效排除光照条件和场景背景条件的影响,重建效率较高,在光谱相机的光谱反射率重建中被普遍采用。比较测量法通常采用标准白板作为参考物,但实际应用中,经常会遇到目标场景空间位置不便放置标准白板的情况。针对这种情况,研究采用LCTF光谱相机采集的目标场景中亮度高的颜色作为参考的比较测量法进行目标物的光谱反射率重建来解决上述问题。实验以美国X-Rite的Gretg Macbeth Color Checker(MCC)色卡作为目标物,分别参考亮度高的五个不同色块,运用比较测量法完成红、绿、蓝三个色块的光谱反射率重建。将重建后三个色块的光谱反射率与采用台式分光光度计(X-Rite Color Eye7000A)测量的标准光谱反射比进行比较。结果显示,重建后的红、绿、蓝三个色块的光谱反射率曲线与用分光光度计测量的标准光谱反射率曲线的形状基本相似,每组曲线的均方根误差均小于0.05;重建的蓝色色块的光谱反射率以参考与其光谱反射比接近的蓝绿色重建的效果最好;重建的红色和绿色色块的光谱反射率以除白色外亮度最高的黄色为参考重建的效果最好;二者均比参考标准白板的反射率重建效果好。实验结果说明采用目标场景中亮度高目视效果明显的色块作为参考对象可被用来进行LCTF光谱相机的光谱反射率重建。该方法有效扩大了比较测量法以及液晶调谐光谱成像系统的应用效率。
基金supported by the National Natural Science Foundation of China (Grant No.42171311)the Open Fund of State Key Laboratory of Remote Sensing Science (Grant No.OFSLRSS202218)+1 种基金the Key Research and Development Program of the Hainan Province,China (Grant No.ZDYF2021SHFZ105)the Training Program of Excellent Master Thesis of Zhejiang Ocean University.
文摘The acquisition of digital regional-scale information and ecological environmental data has high requirements for structural texture,spatial res-olution,and multiple parameter categories,which is challenging to achieve using satellite remote sensing.Considering the convenient,facilitative,and flexible characteristics of UAV(unmanned air vehicle)remote sensing tech-nology,this study selects a campus as a typical research area and uses the Pegasus D2000 equipped with a D-MSPC2000 multi-spectral camera and a CAM3000 aerial camera to acquire oblique images and multi-spectral data.Using professional software,including Context Capture,ENVI,and ArcGIS,a 3D(three-dimensional)campus model,a digital orthophoto map,and multi-spectral remote sensing map drawing are realized,and the geometric accuracy of typical feature selection is evaluated.Based on a quantitative remote sensing model,the campus ecological environment assessment is performed from the perspectives of vegetation and water body.The results presented in this study could be of great significance to the scientific management and sustainable development of regional natural resources.
基金the National Natural Science Foundation of China (Grant No. 60478033)the Doctoral Foundation of Hebei Province of China (Grant No. B2003119)the Science and Technology Project of Hebei Province of China (Grant No. 05215102)
文摘The fluorescence spectra of three different dyes adsorbed on the tabular and cubic AgBr microcrystals are obtained by the picosecond time-resolved streak camera technique. The dependence of the ultrafast electron transferring from dye-aggre-gates to the conduction band of AgBr and the efficiency of spectral sensitization on different kinds of dyes with different concentrations is analyzed. Further more,the microcosmic mechanism of the sensitization process is discussed. It is found that the fluorescence decay curves are fitted very well by the double exponential func-tion,consisting of a slow component and a fast one with large amplitude. We con-sider this fast one mainly attributable to the electron transfer from dye J-aggre-gates to the conduction band of AgBr.
基金This work was supported by National Natural Science Foundation of China No.19775010.
文摘A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pres- sure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be (2). Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure.
