共查询到20条相似文献，搜索用时 46 毫秒
1.
2.
Parametric least squares collocation was used in order to study the detection of systematic errors of satellite gradiometer
data. For this purpose, simulated data sets with a priori known systematic errors were produced using ground gravity data
in the very smooth gravity field of the Canadian plains. Experiments carried out at different satellite altitudes showed that
the recovery of bias parameters from the gradiometer “measurements” is possible with high accuracy, especially in the case
of crossing tracks. The mean value of the differences (original minus estimated bias parameters) was relatively large compared
to the standard deviation of the corresponding second-order derivative component at the corresponding height. This mean value
almost vanished when gravity data at ground level were combined with the second-order derivative data set at satellite altitude.
In the case of simultaneous estimation of bias and tilt parameters from ∂2
T/∂z
2“measurements”, the recovery of both parameters agreed very well with the collocation error estimation.
Received: 10 October 1996 / Accepted 25 May 1998 相似文献
3.
This paper reports acreage, yield and production forecasting of wheat crop using remote sensing and agrometeorological data for the 1998–99 rabi season. Wheat crop identification and discrimination using Indian Remote Sensing (IRS) ID LISS III satellite data was carried out by supervised maximum likelihood classification. Three types of wheat crop viz. wheat-1 (high vigour-normal sown), wheat-2 (moderate vigour-late sown) and wheat-3 (low vigour-very late sown) have been identified and discriminated from each other. Before final classification of satellite data spectral separability between classes were evaluated. For yield prediction of wheat crop spectral vegetation indices (RVI and NDVI), agrometeorological parameters (ETmax and TD) and historical crop yield (actual yield) trend analysis based linear and multiple linear regression models were developed. The estimated wheat crop area was 75928.0 ha. for the year 1998–99, which sowed ?2.59% underestimation with land record commissioners estimates. The yield prediction through vegetation index based and vegetation index with agrometeorological indices based models were 1753 kg/ha and 1754 kg/ha, respectively and have shown relative deviation of 0.17% and 0.22%, the production estimates from above models when compared with observed production show relative deviation of ?2.4% and ?2.3% underestimations, respectively. 相似文献
4.
《ISPRS Journal of Photogrammetry and Remote Sensing》2000,55(1):13-33
Relative or absolute elevation extraction from satellite radar data has been an active research topic for more than 20 years. Various investigations have been made on different methods depending on the predominant “fashion” and data availability, leading each time to new developments to improve the capability and the applicability of each method. The paper presents an update of the state-of-the-art of elevation extraction from satellite SAR data. The performance and limitations of four different methods (clinometry, stereoscopy, interferometry and polarimetry) are reviewed, as well as their applicability to different satellite SAR sensors. Their advantages and disadvantages and how they are addressed during the data processing are also analysed. Finally, concluding remarks look at the complementarity aspects of each method to make the best use of the existing and future radar data for elevation extraction. 相似文献
5.
6.
Peter Reinartz Rupert MüllerPeter Schwind Sahil SuriRichard Bamler 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(1):124-132
Orthorectification of satellite data is one of the most important pre-processing steps for application oriented evaluations and for image data input into Geographic Information Systems. Although high- and very high-resolution optical data can be rectified without ground control points (GCPs) using an underlying digital elevation model (DEM) to positional root mean square errors (RMSEs) between 3 m and several hundred meters (depending on the satellite), there is still need for ground control with higher precision to reach lower RMSE values for the orthoimages. The very high geometric accuracy of geocoded data of the TerraSAR-X satellite has been shown in several investigations. This is due to the fact that the SAR antenna measures distances which are mainly dependent on the terrain height and the position of the satellite. The latter can be measured with high precision, whereas the satellite attitude need not be known exactly. If the used DEM is of high accuracy, the resulting geocoded SAR data are very precise in their geolocation. This precision can be exploited to improve the orientation knowledge and thereby the geometric accuracy of the rectified optical satellite data. The challenge is to match two kinds of image data, which exhibit very different geometric and radiometric properties. Simple correlation techniques do not work and the goal is to develop a robust method which works even for urban areas, including radar shadows, layover and foreshortening effects. First the optical data have to be rectified with the available interior and exterior orientation data or using rational polynomial coefficients (RPCs). From this approximation, the technique used is the measurement of small identical areas in the optical and radar images by automatic image matching, using a newly developed adapted mutual information procedure followed by an estimation of correction terms for the exterior orientation or the RPC coefficients. The matching areas are selected randomly from a regular grid covering the whole imagery. By adjustment calculations, parameters from falsely matched areas can be eliminated and optimal improvement parameters are found. The original optical data are orthorectified again using the delivered metadata together with these corrections and the available DEM. As proof of method the orthorectified data from IKONOS and ALOS-PRISM sensors are compared with conventional ground control information from high-precision orthoimage maps of the German Cartographic Survey. The results show that this method is robust, even for urban areas. Although the resulting RMSE values are in the order of 2-6 m, the advantage is that this result can be reached even for optical sensors which do not exhibit low RMSE values without using manual GCP measurements. 相似文献
8.
Forecasting vegetation greenness with satellite and climate data 总被引：1，自引：0，他引：1
A new and unique vegetation greenness forecast (VGF) model was designed to predict future vegetation conditions to three months through the use of current and historical climate data and satellite imagery. The VGF model is implemented through a seasonality-adjusted autoregressive distributed-lag function, based on our finding that the normalized difference vegetation index is highly correlated with lagged precipitation and temperature. Accurate forecasts were obtained from the VGF model in Nebraska grassland and cropland. The regression R/sup 2/ values range from 0.97-0.80 for 2-12 week forecasts, with higher R/sup 2/ associated with a shorter prediction. An important application would be to produce real-time forecasts of greenness images. 相似文献
9.
N Ravi N K Patel R R Navalgund S Panigrahy R N Dash 《Journal of the Indian Society of Remote Sensing》1992,20(1):43-49
Remotely-sensed data transformed into a vegetation index (radiance ratio of near infrared to red) has been related to district rice yields for Orissa using IRS-1A LISS-I data of kharif seasons 1988–89 and 1989–90. Using the empirical relation of the first year, estimation of rice yield has been done for the 1989–90 kharif season. Deviations in the districts of coastal tract and central tableland ranged from 1.9 to 11.1 percent whereas deviations were larger in Eastern Ghat and Northern plateau of Orissa. 相似文献
10.
R. D. Ray 《Journal of Geodesy》2007,81(4):247-257
The ERS-1, ERS-2 and Envisat series of satellite altimeters provide the only extensive datasets that could conceivably be
usedto constrain ocean tide models in high latitudes. Their sun-synchronous sampling, however, severely limits theobservations
of solar tides, especially the principal semidiurnal S2 constituent. The Munk–Cartwright response method is anatural choice when attempting to analyze sun-synchronous data. The
present study examines various ways a response analysis might be implemented to extract tides from ERS data. Admittances expressed
as simple linear or constant functions of frequency cansometimes improve estimates over standard parameterizations, especially
if done in conjunction with a reasonably accurate priorsolution. Some form of regularization, such as ridge regression, is
also shown to improve the estimates. The approach provesbeneficial in a test for the southern Indian Ocean tides. It offers
some promise for regions otherwise void of usefulobservations. 相似文献
11.
12.
13.
14.
本文针对测高卫星轨道及地面轨迹的独有特点,较系统地研究了卫星测高数据处理的理论与方法,内容包括测高卫星径向轨道误差的时域特征分析与空域特征分析、共线轨迹与交叉点分布等的谱特征、整体求解法的研究以及ＴＯＰＥＸ测高数据的初步计算与分析。（１）系统论述了卫... 相似文献
15.
Landsat8卫星遥感数据预处理方法 总被引：1，自引：0，他引：1
《国土资源遥感》2016,(2)
Landsat系列卫星是由美国航空航天局和美国地质调查局共同管理的资源遥感系列卫星,40多a来为地球遥感探测活动提供了大量清晰而稳定的图像数据。卫星遥感数据预处理是获取优质遥感基础图像的第一步,对后续各级卫星遥感产品的质量有着很重要的影响。针对Landsat8卫星原始数据,对卫星下传所采用的空间数据传输协议和数据传输格式进行了详细的解析,分析了原始数据从解同步、数据帧解析、任务数据包解析、图像数据获取直到生成0级图像产品的步骤;特别针对存在无损数据压缩的陆地成像仪(operational land imager,OLI)数据,讨论了基于空间数据系统咨询委员会(consultative committee for space data systems,CCSDS)相关标准进行无损数据解压缩处理的方法和过程。经数据预处理得到的Landsat8卫星0级图像产品,可为Landsat8卫星数据应用提供优质的基础图像。 相似文献
16.
The crossover adjustment plays a central role in the processing of satellite altimeter measurements. The usual procedure
is to form sea surface height differences at crossover points, solve for the radial orbit error (with due attention to the
singular nature of the estimation problem) and then to construct altimetric sea-level maps using the mean sea surface heights
at the crossover points. Our approach is very different, to make direct use of measurements at crossover points without differencing
and to estimate simultaneously orbit parameters, mean sea surface height and sea surface height variability in a single, unified
adjustment. The technique is suited for repeat data over an area small enough that adjoining passes may be considered to be
parallel and to permit the solution of a set of linear equations of dimension equal to the number of crossover points. The
size of the numerical problem is almost independent of the number of repeat cycles of the altimeter mission. Explicit recognition
is given to the rank defect of the least-squares estimation problem; we show that, for an orbit model with r parameters, the rank defect of the local crossover problem is exactly r
2. The defect may be overcome by choosing an appropriate set of constraints – either giving a best fit of mean sea surface
heights to a reference surface, or minimising orbit parameters, or a minimum norm solution in which both mean sea surface
heights and orbit parameters are minimised. There is no need to choose a reference pass, all passes are treated equally and
data gaps are easily accommodated. Numerical results are presented for the south-western Indian Ocean, based on the first
2 years of altimeter data from the Geosat Exact Repeat Mission.
Received: 31 May 1996 / Accepted: 19 April 1997 相似文献
17.
针对如何在时间序列尺度上利用多源时空融合方法高精度地重构高分辨率遥感影像的问题,该文提出了一种基于增强字典学习样本空间的单数据对稀疏学习融合算法,并利用现有稀疏学习算法、STARFM算法以及半物理模型对Landsat与MODIS卫星数据进行双向融合实验。结果表明:随着样本尺寸及空间的拓展,改进后的稀疏学习算法能够获得比原始算法、STARFM、半物理模型等算法更优的融合结果,其中ERGAS可达15.0以内、SSIM可达84%以上,并且融合质量对高、低分辨率图像间的空间尺度差异性不敏感。通过采用更高效的在线字典学习算法,该融合方法的处理效率与应用价值有望得到极大提升。 相似文献
18.
19.
20.
机载WIDAS数据的Landsat卫星反照率初步验证 总被引：1，自引：1，他引：0
随着精细化监测的需求,中高空间分辨率的地表反照率产品逐渐成为气候模型的主要输入。目前,中高空间分辨率反照率产品的验证主要基于地表站点的通量塔观测数据,区域机载飞行数据的验证依然相对较少。因此,本文基于区域机载数据验证Landsat反照率产品。针对内蒙古自治区根河森林试验区所获取的机载红外广角双模式成像仪(WIDAS)多角度反射率数据,应用BRDF原型反演算法估算其反照率,分析了应用机载数据验证中高空间分辨率反照率产品的潜力。2016年内蒙古根河森林试验区机载WIDAS飞行多角度观测的可用多角度范围为25°,以前的研究表明BRDF原型反照率反演算法表现出对小观测角度的反照率反演结果的鲁棒性。因此,机载WIDAS反照率在一定程度可用于星载反照率的验证。首先,基于核驱动模型和各向异性平整指数(AFX)提取了试验区4种MODIS二向性反射分布函数(BRDF)原型;然后,将其作为先验知识应用到根河森林WIDAS机载数据的反照率反演中;最后,用WIDAS反照率和单个地面通量塔观测的反照率对Landsat卫星数据的反照率进行初步验证。验证结果表明Landsat反照率与WIDAS反照率结果较为一致,但略有低估,总体均方根误差(RMSE)约为0.02,偏差为0.0057。在多角度观测范围较小时,BRDF原型的反照率反演算法可为星载地表反照率的验证提供了一种有效的验证手段。 相似文献