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101.
为了鉴定陆地卫星5号系统纠正TM图像产品的精度,我们以1:5万地形图为基准,对四景TM图像作了精度分析。结果表明,系统纠正后的TM图像产品,内部几何精度相当好,有较小的旋转、比例误差。采用一阶多项式即可建立TM图像和地形图之间的几何关系,其误差为1个像元左右。TM图像的大地绝对误差,可通过将整个TM图像沿x,y方向平移的方法来加以校正。 相似文献
102.
周忠谟 《武汉大学学报(信息科学版)》1986,(3)
本文从地面三角网和卫星同联合平差的原理出发,讨论了对卫星网的最低精度要求。指出,为改善地面三角网而布设卫星网时,卫星观测站的最低精度主要决定于以下因素: ——地面三角网的精度; ——对地面三角网精度改善程度的要求; 一卫星观测站之间的距离。这里通过模拟计算对卫星网的最低精度要求与上列因素之间的关系作了数字分析,并建立了估算卫星网最低精度的数学模型。预期,在一般情况下,该模型的估算误差将不会超过10%。 相似文献
103.
104.
105.
The second vertical derivatives of gravity and magnetic potential are widely used in geophysical prospecting because of their
better resolution. On the same basis an attempt has been made to obtain the expressions for the second vertical derivative
of the electrical potential and to compute its nature for comparison. Derivative responses over a two-layered earth and also
over an anticlinal structure have been computed and it is shown that the second vertical derivative sounding could be employed
for greater accuracy in finding out the thickness of such beds or the inclination of the sides of the anticline and its depth
when compared with normal resistivity sounding 相似文献
106.
DIAGNOSTIC ANALYSIS AND VERIFICATION OF PREDICTION OF THE TROPICAL PACIFIC SEA SURFACE TEMPERATURE ANOMALIES
DURING 1997 ~ 1998 总被引:1,自引:1,他引:0
By comparing with ENSO events that ever happened in the history, the basic features and probable
causes of the anomalous sea surface temperature of the tropical Pacific Ocean during 1997 and 1998 have been
analyzed diagnostically. It is found that the 1997/1998 El Nino had significant abnormalities and peculiarities. It
differs from the previous El Ni?o events falling into the simple “eastern pattern” or “western pattern”. The
predictions of 1997/1998 El Ni?o event have also been tested with an intermediate ocean-atmosphere coupled
dynamic model. The results show that the skills of the 0~24 lead month forecasts for the warm event are all
above 0.5. The predictions of the mature phase and the later stages of the warm event are better than those of the
beginning phase. 相似文献
107.
108.
Lauren Patterson Marie Urban Aaron Myers Budhendra Bhaduri Eddie Bright Phillip Coleman 《GeoJournal》2007,69(1-2):93-102
Geospatial technologies and digital data have developed and disseminated rapidly in conjunction with increasing computing
efficiency and Internet availability. The ability to store and transmit large datasets has encouraged the development of national
infrastructure datasets in geospatial formats. National datasets are used by numerous agencies for analysis and modeling purposes
because these datasets are standardized and considered to be of acceptable accuracy for national scale applications. At Oak
Ridge National Laboratory a population model has been developed that incorporates national schools data as one of the model
inputs. This paper evaluates spatial and attribute inaccuracies present within two national school datasets, Tele Atlas North
America and National Center of Education Statistics (NCES).
Schools are an important component of the population model, because they are spatially dense clusters of vulnerable populations.
It is therefore essential to validate the quality of school input data. Schools were also chosen since a validated schools
dataset was produced in geospatial format for Philadelphia County; thereby enabling a comparison between a local dataset and
the national datasets.
Analyses found the national datasets are not standardized and incomplete, containing 76 to 90 percent of existing schools.
The temporal accuracy of updating annual enrollment values resulted in 89 percent inaccuracy for 2003. Spatial rectification
was required for 87 percent of NCES points, of which 58 percent of the errors were attributed to the geocoding process. Lastly,
it was found that by combining the two national datasets, the resultant dataset provided a more useful and accurate solution. 相似文献
109.
A probabilistic fog forecast system was designed based on two high resolution numerical 1-D models called COBEL and PAFOG.
The 1-D models are coupled to several 3-D numerical weather prediction models and thus are able to consider the effects of
advection. To deal with the large uncertainty inherent to fog forecasts, a whole ensemble of 1-D runs is computed using the
two different numerical models and a set of different initial conditions in combination with distinct boundary conditions.
Initial conditions are obtained from variational data assimilation, which optimally combines observations with a first guess
taken from operational 3-D models. The design of the ensemble scheme computes members that should fairly well represent the
uncertainty of the current meteorological regime. Verification for an entire fog season reveals the importance of advection
in complex terrain. The skill of 1-D fog forecasts is significantly improved if advection is considered. Thus the probabilistic
forecast system has the potential to support the forecaster and therefore to provide more accurate fog forecasts. 相似文献
110.
矢量GIS数据位置精度评价 总被引:5,自引:0,他引:5
论述了采用野外测量法评价矢量GIS数据位置精度的过程,为精确评价位置精度提出了相应的质量控制措施,讨论了必要的检测点数目、检测点选择等,并对该方法的适用范围作了说明。 相似文献