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31.
Yong Ge Sanping Li V. Chris Lakhan Arko Lucieer 《International Journal of Applied Earth Observation and Geoinformation》2009
The existence of uncertainty in classified remotely sensed data necessitates the application of enhanced techniques for identifying and visualizing the various degrees of uncertainty. This paper, therefore, applies the multidimensional graphical data analysis technique of parallel coordinate plots (PCP) to visualize the uncertainty in Landsat Thematic Mapper (TM) data classified by the Maximum Likelihood Classifier (MLC) and Fuzzy C-Means (FCM). The Landsat TM data are from the Yellow River Delta, Shandong Province, China. Image classification with MLC and FCM provides the probability vector and fuzzy membership vector of each pixel. Based on these vectors, the Shannon's entropy (S.E.) of each pixel is calculated. PCPs are then produced for each classification output. The PCP axes denote the posterior probability vector and fuzzy membership vector and two additional axes represent S.E. and the associated degree of uncertainty. The PCPs highlight the distribution of probability values of different land cover types for each pixel, and also reflect the status of pixels with different degrees of uncertainty. Brushing functionality is then added to PCP visualization in order to highlight selected pixels of interest. This not only reduces the visualization uncertainty, but also provides invaluable information on the positional and spectral characteristics of targeted pixels. 相似文献
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By using observed CHAMP orbit ephemeredes and MSISE-90 dry air model and regarding the earth as a sphere and an ellipsoid respectively, phase delays are simulated and the simulated data are retrieved under different schemes. The comparison between the inverted temperature profiles and the model temperature profiles shows that by inverting observed data, we will get temperature results with large errors if the effect of Earth’s oblateness is omitted. The correction method is proved to be effective because the temperature errors decreased obviously with this method. 相似文献
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Pedestrian navigation has become an important theoretical and practical research topic in many disciplines such as cartography, geographical information science, global and indoor positioning, spatial behavior, psychology, sociology, and neuroscience. Many research studies view pedestrian navigation using process-oriented and goal-directed approaches. However, this paper revisits people’s needs in pedestrian navigation and classifies their needs as three layers: physical sense layer, physiological safety layer, and mental satisfaction layer according to Maslow’s theory. This paper introduces a people-centric framework for pedestrian navigation theory based on these three layers and discusses theoretical challenges for meeting each layer of people’s needs. These challenging theories may represent promising and valuable research and promote usage of pedestrian navigation systems or devices in the future. 相似文献
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球谐函数变换快速计算扰动引力 总被引:1,自引:0,他引:1
在球谐函数变换基础上,利用新极下轨道的特殊性,在新坐标下引入Clenshaw求和计算轨道扰动引力。从理论上对比分析了传统方法、球谐函数变换方法和改进方法的计算速度和存储模型需要的物理空间。模拟试验分别采用3种方法计算了一段轨道的扰动引力,试验结果表明,改进的球谐函数变换方法比传统球谐函数变换方法计算速度可提高100倍,数据存储量仅占传统方法的3%。 相似文献
36.
在2003年10月27日和28日观测的太湖水质光谱试验数据的支持下,利用数值模拟方法研究了试验数据误差与水质浓度反演模型经验常数之间的关系。研究结果表明,当试验数据误差分别服从正态分布与均匀分布时,反演模型的经验常数随着试验数据误差的增加而呈发散状态。根据试验数据误差与反演精度的关系可知,26.58%的试验误差对应着30%的反演精度,这就意味着在不考虑遥感影像处理所产生误差的前提下,严格控制试验数据误差在26.58%以内,是反演精度打破±30%的技术瓶颈的关键要素之一。 相似文献
37.
Maarit Middleton Paavo Nrhi Raimo Sutinen 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(3):287-297
In a humid northern boreal climate, the success rate of artificial regeneration to Scots pine (Pinus sylvestris L.) can be improved by including a soil water content (SWC) based assessment of site suitability in the reforestation planning process. This paper introduces an application of airborne visible-near-infrared imaging spectroscopic data to identify suitable subregions of forest compartments for the low SWC-tolerant Scots pine. The spatial patterns of understorey plant species communities, recorded by the AISA (Airborne Imaging Spectrometer for Applications) sensor, were demonstrated to be dependant on the underlying SWC. According to the nonmetric multidimensional scaling and correlation results twelve understorey species were found to be most abundant on sites with high soil SWCs. The abundance of bare soil, rocks and abundance of more than ten species indicated low soil SWCs. The spatial patterns of understorey are attributed to time-stability of the underlying SWC patterns. A supervised artificial neural network (radial basis functional link network, probabilistic neural network) approach was taken to classify AISA imaging spectrometer data with dielectric (as a measure volumetric SWC) ground referencing into regimes suitable and unsuitable for Scots pine. The accuracy assessment with receiver operating characteristics curves demonstrated a maximum of 74.1% area under the curve values which indicated moderate success of the NN modelling. The results signified the importance of the training set’s quality, adequate quantity (>2.43 points/ha) and NN algorithm selection over the NN algorithm training parameter optimization to perfection. This methodology for the analysis of site suitability of Scots pine can be recommended, especially when artificial regeneration of former mixed wood Norway spruce (Picea abies L. Karst) - downy birch (Betula pubenscens Ehrh.) stands is being considered, so that artificially regenerated areas to Scots pine can be optimized for forestry purposes. 相似文献
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大型沉水植物狐尾藻不同盖度的光谱特征 总被引:3,自引:0,他引:3
地物特征与其光谱特征的关系是解译遥感影像的关键。本研究利用ASD便携式地物光谱仪对上海崇明国际湿地公园人工湖中的沉水植物狐尾藻的反射光谱进行了初步研究。结果表明,随狐尾藻盖度的增加,其光谱反射率、一阶和二阶导数红边斜率的峰值也相应增加,不同盖度狐尾藻的光谱反射率的差异主要表现在500—650nm和700—900nm波段范围。分别对狐尾藻盖度与这些波段的光谱反射率及根据一阶和二阶导数获得的光谱指数进行回归分析,得到了较好的线性关系。应用回归分析得到的线性方程,可以根据测定的光谱反射率定量反演水体中的狐尾藻盖度。研究结果可为监测大型沉水植物的高光谱遥感影像解译和分类提供技术支撑,为大尺度遥感监测沉水植物的分布和动态变化提供科学依据。 相似文献