In flight MTF monitoring and compensation for CCD camera on CBERS-02

All image systems cause a blurring of the scene radiance field during image acquisi- tion. Accurate characterization of this blurring is referred to as the modulation transfer function (MTF)[1]. The MTF is a fundamental imaging system design specification and system quality metric often used in remote sensing. It results from the cumulative effects of the instrumental optics (diffraction, aberrations, focusing error), integration on a pho- tosensitive surface, charge diffusion along the arra…     

Comparison of the influence factors onNDVI for CCD camera and WFI imager on CBERS-02

CCD and WFI are payloads in the visible light and near infrared bands on CBERS satellites and they have not been applied widely, especially WFI. This article mainly probes into the potential of these two sensors’ application in the vegetation monitoring and analyses the influences of radiometric calibration, atmosphere conditions and sun-observing geometry, etc. onNDVI obtained from these two sensors respectively. In addition it analyses the effect of the spectral response difference of red and near infrared spectral bands in CCD and WFI sensors onNDVI. Results indicate that radiometric calibration is the most important factor onNDVI, which cannot be applied to vegetation monitoring without radiometric calibration. Results also demonstrate that near surfaceNDVI is different greatly from that of TOA which change with atmosphere conditions. The study shows thatNDVI is also affected by the non-lambertian character of surface and the change of the atmospheric path with the observing geometry. AndNDVI of WFI is higher than that of CCD. They are very different because of their spectral diffirence, but they have a good linear relevant relationship.

     

Comparison of the influence factors on NDVI for CCD camera and WFI imager on CBERS-02

China Brazil Earth Resources Satellites (CBERS) have many payloads, among them there are a high resolution Charge Coupled Device (CCD) Camera and the Wide Field Image (WFI). CCD’s spatial resolution in nadir is 19.5 meters and its swath width is 113 kilometers. It has 4 wave bands and a panchromatic wave band in visible and near infra- red spectral band. Side looking is one of the main functions of CCD and the side looking range is ±32°. WFI has one visible band and one near inf…     

Radiometric cross-calibration of the CBERS-02 CCD camera with the TERRA MODIS

With the requirement of quantitative application of remote sensing, it is more pressing to improve the accuracy of remote sensing. Slater proposed a calibration method using a large homogeneous surface target [1], which has been proved promising and has been applied to many sensors[2―10], such as TM, ETM+, HRVIR. However, this method re-quired so much labor and fund that it could not produce enough calibration coefficients. In addition, it could not be applied to history data. Later, many…     

Water target based cross-calibration of CBERS-02 CCD camera with MODIS data

In order to make quantitative watercolor sensing with China-Brazil Earth Resources Satellite (CBERS-02) CCD camera, the MODIS data with higher accuracy is used to cross-calibrate the CCD camera over water targets. In homogeneous clear water area, two pairs of images obtained over the same area on the same day by the two sensors are selected. The top-of-atmosphere (TOA) radiances of the multispectral bands of CCD are calculated with the water and aerosol parameters from MODIS based on a water-atmosphere radiative transfer algorithm. The stripes in CCD image that caused by unequal response of the CCD array detectors are firstly removed before making the cross-calibration. The same part of CCD detectors is selected for the calibrations in the two images to eliminate the residual error of destriping and uniformity correction for the focus plane irradiance. It is shown that the calibration results from two different images are consistent. The error of this method is about 5%.     

Water target based cross-calibration of CBERS-02 CCD camera with MODIS data

The CBERS-02, the second satellite of China Brazil Earth Resources Satellite series, was launched on Oct. 21, 2002. Onboard the satellite, there are three major sensors, a CCD camera, a wide field imager and an infrared multispectral scanner (http://www. cresda.com). The purpose of this paper is to calibrate the CCD camera with a methodol- ogy of cross-calibration. The spatial resolution of the multispectal bands of CCD camera is 19.5 m, the swath is about 115 km. It is capable of side…     

Radiometric cross-calibration of the CBERS-02 CCD camera with the TERRA MODIS

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.     

Biomass estimation and uncertainty analysis based on CBERS-02 CCD camera data and field measurement

The study site is located in Qianyanzhou experimental station and the surrounding area. Based on CBERS-02 satellite data and field measurement, we not only discussed the relationship between NDVI and biomass of two species of coniferous plantations, namely,Pinus massoniana Lamb andPinus elliottii Engelm, but also introduced the biomass models based on NDVI. The comparison between measured biomass in Qianyanzhou and biomass derived from CBERS-02 CCD data showed that it is feasible to estimate biomass based on NDVI. But its limitations cannot be ignored. This kind of model depends on the dominant vegetation species. There are some effect factors in estimating biomass based on NDVI. This paper analyzes these factors based on fine-resolution CBERS-02 CCD data and some conclusions are drawn: In Qianyanzhou, the area with good vegetation coverage, the nonlinearity of NDVI has little influence on scaling-up of NDVI. As a result of surface heterogeneity, scaling-up can cause NDVI within each pixel to change. Because scaling-up can cause pixel attribute to change, the applicability of biomass model is one of the sources of error in estimating biomass.     

Biomass estimation and uncertainty analysis based on CBERS-02 CCD camera data and field measurement

The study on terrestrial ecosystem carbon cycle has been the focus of global change research and regional sustainable development research. It is well known that terrestrial ecosystem is the largest unknown area[1] in seeking the missing carbon sink[2]. Because it is allowed in the Kyoto Protocol that adding CO2 absorption by foresting and reforesting can offset greenhouse gases emission, the mechanism of carbon sequestration and thedistribution and mapping of carbon pool have been the focus …     

Cotton pixel identification with CBERS-02 CCD data based on spectral knowledge

CBERS-02 has three sensors, Charged Coupled Device (CCD), Infrared Multispectral Scanner (IRMSS) and Wide Field Imager (WFI). Similar to Landsat TM, CCD has 4 visible and near-infrared bands and one panchromatic band. The wavelength ranges are respectively 0.45-0.52 μm, 0.52-0.59 μm, 0.63-0.69 μm, 0.77-0.89 μm and 0.51 -0.73 μm. The spatial resolution is 19.5 m. CBERS-02 has three ground stations in Beijing, Guangzhou and Urumchi, which makes it cover the whole territory. …     

Cotton pixel identification with CBERS-02 CCD data based on spectral knowledge

In this paper thein-situ experiment data are collected from the Spectral Library to estimate the possible values of the primary structural parameters in each cotton growing season by statistics. Based on these values the spectra of the cotton major growing seasons were simulated and analyzed using the canopy reflectance model, SAILH. In this way we also simulated the cotton pixel spectra corresponding to CBERS-02 CCD and took them as the reference spectra for spectra fitting. Then No. 143 Regiment of No. 8 Agricultural Division of Xinjiang Production and Construction Corps (XPCC) was chosen as the study area, and two spectra fitting methods, Mahalanobis distance and spectra angle, were used to identify cotton pixel from CBERS-02 CCD image of the study area. At last we analyzed the effect of the calibration coefficients error on cotton identifying. The results showed that within 4% error the spectral angle classifier can still have a good performance.     

Comparison of the influence factors on<Emphasis Type="Italic">NDVI</Emphasis> for CCD camera and WFI imager on CBERS-02

CCD and WFI are payloads in the visible light and near infrared bands on CBERS satellites and they have not been applied widely, especially WFI. This article mainly probes into the potential of these two sensors’ application in the vegetation monitoring and analyses the influences of radiometric calibration, atmosphere conditions and sun-observing geometry, etc. onNDVI obtained from these two sensors respectively. In addition it analyses the effect of the spectral response difference of red and near infrared spectral bands in CCD and WFI sensors onNDVI. Results indicate that radiometric calibration is the most important factor onNDVI, which cannot be applied to vegetation monitoring without radiometric calibration. Results also demonstrate that near surfaceNDVI is different greatly from that of TOA which change with atmosphere conditions. The study shows thatNDVI is also affected by the non-lambertian character of surface and the change of the atmospheric path with the observing geometry. AndNDVI of WFI is higher than that of CCD. They are very different because of their spectral diffirence, but they have a good linear relevant relationship.     

Study of thin cloud removal method for CBERS-02 image

For several years, China Brazil Earth Resources Satellie (CBERS) data have been ap- plied to agriculture, irrigation works, zoology construction, environment protection, sustainable development, resource survey, etc. The applications have played important roles in country economic construction, and they have brought favorable social and economic benefits. They provide references for government decision-making and effi- cient information for the development of correlative industries. Furthe…     

三线阵CCD立体测绘卫星像移姿态跟踪补偿研究

介绍了三线阵CCD传感器的成像原理,分析了由于地球自转角速度的存在而产生三线阵CCD传感器像移的机理.在规划姿态跟踪策略的基础上,建立了有效成像面积和姿态机动方式的数学关系,求解关系式最大值以得到像移补偿的姿态跟踪机动策略.最后给出了姿态跟踪过程中的目标姿态和目标姿态角速度变化规律.     

Study of thin cloud removal method for CBERS-02 image

The China Brazil Earth Resources Satellite (CBERS) ended the dependence on foreign satellites. Along with the series of CBERS and the enhancement of satellite applications, it is necessary to search correlative data processing methods. Because cloud appears in the atmosphere, an image with clear sky conditions is often hard to obtain. How to remove cloud is an important sector of increasing image quality. An improved homomorphism filtering method is adopted to remove thin cloud qualitatively at first, and all bands are selected to classify pixels. Based on the fact that visible band images contain more aerosol effects than infrared bands, visible bands are used to determine clear or hazy regions and the reflectances of different surface classes in clear regions are calculated. At last the mean reflectance of the same classes in clear and hazy regions is matched to remove cloud. The image visual effect is improved; meanwhile, the ground reflectance is retrieved to meet the needs of remote sensing quantification.     

A fast atmospheric correction method based on CBERS-02 data

为实现高分2号图像(GF2)业务化大气校正,利用矢量6S模型(6SV)将辐射传输散射与吸收进行分离计算,其中散射部分采用涵盖各种大气模式、气溶胶类型、成像几何等条件下的大气校正查找表(look-up tables,LUTs)表示,大气吸收部分采用6SV拟合计算的6种大气模式下大气透过率的经验公式表示,这种处理有效简化了查找表大小. 在内存4GB、主频3.10GHz条件下,通过比较基于本查找表方法和基于FLAASH大气校正软件对北京地区一景GF2数据处理. 结果表明:以6SV模型直接大气校正法结果作为真值,两者的绝对误差分别为0.8%和2.6%,处理时间分别为77s和240s,该大气校正查找表在处理精度和效率更加适合业务化大气校正.

     

数字CCD摄像机抗纵向晕光驱动时序研究

分析了CCD摄像机纵向晕光的产生原因,提出了一种消除数字CCD摄像机高照度像素上半部分纵向晕光的垂直移位驱动时序设计方法。根据CCD电荷转移时序控制原理,在两帧间插入垂直移位驱动时序,可以清除前一帧产生的饱和电荷,由此可以消除高照度像素上半部分纵向光晕。在ICX205电路板上,测试了本文提出的抗光晕驱动时序,结果表明,所提出的方法可以成功清除高照度像素上半部分纵向光晕。研究结果已应用于智能交通监测。     

Estimating surface evapotranspiration using combined MODIS and CBERS-02 data

Spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIS 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIS data. CBERS-02 data were used to produce land use class of Baiyangdian area, Hebei Province, China in the autumn of 2004. The area ratio of each class in MODIS pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

     

Estimating surface evapotranspiration using combined MODIS and CBERS-02 data

Land surface evapotranspiration is one of the most important components in water cycle between earth and atmosphere, and plays a very important role in the atmosphere, hydrosphere, and biosphere of the planet. It is an urgent task to understand the evapotranspiration process over different surface types and conditions in agriculture, hydrogeology, forest, and ecology for the purpose of using water resources properly. Additionally, land surface evapotranspiration is a key parameter in the synop…     

基于CBERS-02B高分辨率遥感影像分割的最优尺度选取

高分辨遥感影像的信息提取对矿山的监测有着重要意义,影像分割是高分辨率遥感影像信息提取关键的一步．文中以赣州稀土矿山的高分辨率遥感影像为源数据,采用分形网络演化多尺度分割算法对高分辨率遥感影像进行分割,通过Robert算子的边缘提取结果计算分割参数获取分割尺度,并在此基础上设置不同分割尺度对影像进行分割,对比分析分割结果表明,沉淀池的最优分割尺度为35．最后利用分割质量值对分割结果进行评价分析,验证了试验结果的正确性．