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The correlation of multi-angle thermal infrared data and the choice of optimal view angles

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Science china Earth Sciences 2004年第6期47卷 570-576页

作者： fan wenjie1 & xu xiru1,2.1.institute of remote sensing and gis of peking university,Beijing 100871,{2. 2.Center of remote sensing and gis of Beijing Normal university,Beijing 100875,{2. 1. institute of remote {2. and gis of peking university 100871 Beijing China 2. Center of remote sensing and {2. of Beijing Normal university 100875 Beijing China

Based on the matrix formula of thermal infrared radiant system, the components temperature can be retrieved by the inversive matrix. Around the stability problem of retrieved result, the research work we did was focused on (i) the correlation of (wk,j) which is the key to affect the retrieval accuracy, (ii) a general method which can help us find the number of retrievable parameters and evaluate the retrieval error before its performance, (iii) the choice of “optimal viewing angle group” based on the formula of absolute error propagation. The row winter wheat field was chosen as an example. The results can provide a theoretical basis for multi-angle thermal infrared remote sensing and components temperature retrieval.

关键词： components temperature retrieval, correlation, number of retrievable parameters, optimal viewing angle group.

A method for blind separation of components information from mixed pixel

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Progress in Natural Science:Materials International 2006年第07期16卷 760-765页

作者： fan wenjie and {2. xiru ( institute of remote sensing and Geographical Information System, peking university, Beijing 100871, china Center of remote sensing and {12. of Beijing Normal university, Beijing 100875, china) [a]institute of remote {2. and Geographical Information System Peking University Beijing China [b]Center of remote sensing and {2. of Beijing Nornal university Beijing China

In the field of remote sensing, it is important to separate the component information from mixed pixel. If the physical process of remote sensing can be expressed by a set of linear equations, the remote sensing information matrix is equal to the weight matrix multiplied by the component information matrix. Generally speaking, the precondition of retrieval of component information matrix is that the weight matrix is known. However, the blind signal separation (BSS) method can separate the matrix unconditionally, whose basic principle is that the additive information needing separation can be achieved from the statistical characteristics contained in a mass of samples in the remotely sensed information matrix. Therefore, the values of the component information matrix and the weight matrix can be estimated. The wave shape of components can be retrieved by BSS, but the amplitude cannot. In this paper, the plant-soil mixed pixels were chosen as the studying targets in this paper to quantitatively separate the component information and solve the uncertainty of BSS. Simulation and field test verify the reliability of the method. Results show that the BSS can be one of the effective methods of mixed pixel separation, and the foreground of application is very promising.

关键词： mixed pixel component information blind signal separation.

The spatial scaling effect of continuous canopy Leaves Area Index retrieved by remote sensing

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Science china Earth Sciences 2009年第3期52卷 393-401页

作者： xu xiru {2. wenjie TAO Xin institute of remote {2. and gis Peking UniversityBeijing 100871China

Leave Area Index (LAI) is one of the most basic parameters to describe the geometric structure of plant canopies. It is also important input data for climatic model and interaction model between Earth surface and atmosphere, and some other things. The spatial scaling of retrieved LAI has been widely studied in recent years. Based on the new canopy reflectance model, the mechanism of the scaling effect of con- tinuous canopy Leaf Area Index is studied, and the scaling transform formula among different scales is found. Both the numerical simulation and the field validation show that the scale transform formula is reliable.

关键词： spatial scaling effect remotely sensed LAI the true LAI the reflectance model of continuous canopy

A unified canopy bidirectional reflectance (BRDF) model for row ceops

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Science china Earth Sciences 2012年第5期55卷 824-836页

作者： YAN BinYan xu xiru {2. wenjie institute of RS and gis Peking UniversityBeijing 100871China

Row sowing is a basic crop sowing method in china,and thus an accurate Bidirectional Reflectance Distribution Function (BRDF) model of row crops is the foundation for describing the canopy bidirectional reflectance characteristics and estimating crop ecological *** of the macroscopically geometric difference,the row crop is usually regarded as a transition between continuous and discrete vegetation in previous *** row treated as the unit for calculating the four components in the Geometric Optical model (GO model),the formula would be too complex and difficult to *** study focuses on the microscopic structure of row *** the row crop as a result of leaves clumped at canopy scale,we apply clumping index to link continuous vegetation and row ***,the formula of clumping index is deduced *** taking leaf as the basic unit,we calculate the four components of the GO model and develop a BRDF model for continuous vegetation,which is gradually extended to the unified BRDF model for row *** is of great importance to introduce clumping index into BRDF *** order to evaluate the performance of the unified BRDF model,the canopy BRDF data collected in field experiment,"Watershed Allied Telemetry Experiment Research (WATER)",from May 30th to July 1st,2.08 are used as the validation dataset for the simulated *** results show that the unified model proposed in this paper is able to accurately describe the non-isotropic characteristics of canopy reflectance for row *** addition,the model is simple and easy to *** general,there is no irreconcilable conflict between continuous and discrete vegetation,so understanding their common and individual characteristics is advantageous for simulating canopy *** is proven that the four components of the GO model is the basic motivational factor for bidirectional reflectance of all vegetation types.

关键词： row crop BRDF clumping clumping index

A unified model of bidirectional reflectance distribution function for the vegetation canopy

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Science china Earth Sciences 2017年第3期60卷 463-477页

作者： xu xiru {2. wenjie LI JuCai ZHAO Peng CHEN GaoXing institute of remote {2. and Geographic Information System Peking UniversityBeijing 100871China Beijing Key Laboratory of Spatial Information Integration&Its Applications Beijing 100871China

An accurate and operational bidirectional reflectance distribution function （BDRF） canopy model is the basis of quantitative vegetation remote sensing. The canopy reflectance should be approximated as the sum of the single scattering reflectance arising from the sun, pl, and the multiple scattering reflectance arising from the canopy, fin, as their directional characteristics are dramatically different. Based on the existing BRDF model, we obtain a new analytical expression of ρ1 and ρm in this paper, which is suitable for different illumination conditions and different vegetation canopies. According to the geometrical optic model at the leaf scale, the anisotropy of ρ1 can be ascribed to the geometry of the object, sun and the sensor, multiple scale clumping, and the fraction of direct solar radiation and diffuse sky radiation. Then, we parameterize the area ratios of four components： the sunlit foliage, sunlit ground, shadow foliage and shadow ground based on a Poisson distribution, and develop a new approximate analytical single scattering reflectance model. Assuming G=0.5, a recollision probability theory based scattering model is developed which considers the effects of diffuse sky radiation, scattering inside the canopy and rebounds between the canopy and soil. Validation using ground measurements of maize and black spruce forest proves the reliability of the model.

关键词： Vegetation BRDF Unified model Clumping Index Proportion of direct solar radiation and diffuse sky radiation Recollision probability

Study of evolution forecast of the area of the Huanghe River mouth

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Acta Oceanologica Sinica 1993年第2期12卷 249-259页

作者： Guo Yongsheng, xu xuegong, {2. Zhaomu, Wu Peihong and Zhu Xiaoge Department of Geography, Shandong Normal university, Jinan 2.0014, china Department of Geography, peking university, Beijing 100871, china remote sensing Geology Department, Oil Exploration and Exploitation Scientific Research institute, Beijing 100083, china Department of Geography Shangdong Normal University Linan 250014 China China

From 1979 to 1989, the current Qingshuigou course of the Huanghe River formed a sub - delta which resembles a beak extending into the Laizhou Bay. It covers 618 km2.in area. To meet the needs of developing and constructing the Huanghe River Delta and under the presupposition of keeping the current course for 15-2. a, we forecast mainly by using the OM (1, 1) model that the front border of the sub-delta will be close to 119°30'E and its area will become 92. km2.y the end of the year 2.00. The Huanghe River will make land 760 km2.in area.

关键词： Huanghe River mouth Markov chain forecasting method of grey number series

Validation methods of LAI products on the basis of scaling effect

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遥感学报 2015年第1期19卷 134-142页

作者： LIAO Yanran GAI Yingying YAO Yanjuan fan wenjie {2. xiru YAN Binyan institute of remote {2. and gis Peking University Beijing 100871 China Beijing Key Laboratory of Spatial Information Integration & Its Applications Beijing 100871 China institute of Oceanographic Instrumentation Shandong Academy of Sciences Qingdao 266001 China Satellite Environment Center Ministry of Environmental Protection Beijing 100094 China Jackson School of Geosciences the University of Texas at Austin Austin 78712 USA

Validation is one of the most important processes used to evaluate whether remotely sensed products can accurately reflect land surface configuration. Leaf Area Index( LAI) is a key parameter that represents vegetation canopy structures and growth conditions. Accurate evaluation of LAI products is the basis for applying them to land surface models. In this study,validation methods of coarse resolution MODIS and GLASS LAI products for heterogeneous pixels are established on the basis of the scaling effect and the scaling transformation. Considering spatial heterogeneity and growth difference,we transformed LAI from field measurements into a 1 km resolution scale with the aid of middle resolution images. We used average LAI and apparent LAI separately to validate the algorithms and products of MODIS and GLASS LAI. Two study areas,Hebi City and the Yingke Oasis,were selected for validation. Both MODIS and GLASS LAI products underestimate the true LAI in crop area. However,this result cannot be completely attributed to their algorithms. Instead,the primary reason is the heterogeneity and nonuniformity of the coarse *** is evident in the Yingke Oasis,where heterogeneity is significant. Given that GLASS LAI product is the fusion of multiple LAI products,the mean value of this product is closer to the real situation,but the dynamic range is narrower than that of MODIS LAI product.

关键词： validation leaf area index scaling effect scaling transformation

2.00—2.14年呼伦贝尔草原植被覆盖度时空变化分析

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北京大学学报（自然科学版） 2017年第3期53卷 563-572页

作者：彭飞范闻捷徐希孺刘星北京大学遥感与地理信息系统研究所北京100871 安徽理工大学测绘学院淮南232001

以呼伦贝尔草原核心区的新巴尔虎右旗、新巴尔虎左旗、陈巴尔虎旗和鄂温克族自治旗为主要研究区,基于MODIS NDVI数据,利用像元二分模型反演得到植被覆盖度,并结合土地覆盖分类产品,构建2.00—2.14年研究区植被覆盖度时间序列。通过时间... 详细信息

以呼伦贝尔草原核心区的新巴尔虎右旗、新巴尔虎左旗、陈巴尔虎旗和鄂温克族自治旗为主要研究区,基于MODIS NDVI数据,利用像元二分模型反演得到植被覆盖度,并结合土地覆盖分类产品,构建2.00—2.14年研究区植被覆盖度时间序列。通过时间序列分析,从不同的时间和空间尺度分析草原植被覆盖度的变化规律;同时引入覆盖度异常变化点检测算法,并结合该地区同期气象数据,进一步探讨研究区植被覆盖度变化与气象因子之间的内在驱动力关系。结果表明,植被覆盖度在空间分布上主要表现为:从东往西依次递减,特别是研究区西南部,覆盖度最低;15年来研究区植被年际变化总体上呈现前10年下降、后5年缓慢上升的趋势。对植被覆盖度的异常变化进行分析,结果显示:返青期和枯萎期覆盖度的剧烈变化与温度的相关性较大,生长旺季内(7—8)月覆盖度的剧烈变化主要与降水量有关。

关键词：呼伦贝尔草原像元二分模型植被覆盖度(FVC) 时间序列气象因子植被时序变化点检测算法相关性

南方典型山区土地利用变化GPS野外测量方法——以攀枝花仁和区为例

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山地学报 2000年第4期18卷 353-359页

作者：范海生陈秀万李京马蔼乃北京大学遥感与地理信息系统研究所!北京100871

在GPS空间信息技术综合应用于山区土地资源动态监测示范研究背景下 ,总结山地GPS野外测量方法和经验。山地GPS测量作业的主要问题是如何在保证测量数据质量的前提下提高工作效率、减少工作强度。GPS测量数据已成为国土资源动态监测和管... 详细信息

在GPS空间信息技术综合应用于山区土地资源动态监测示范研究背景下 ,总结山地GPS野外测量方法和经验。山地GPS测量作业的主要问题是如何在保证测量数据质量的前提下提高工作效率、减少工作强度。GPS测量数据已成为国土资源动态监测和管理领域的新型数据源

关键词：全球定位系统地理信息系统遥感土地利用变化