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Forest canopy height mapping over China using GLAS and MODIS data

Science China Earth Sciences 2015年第1期58卷 96-105页

作者： YANG Ting WANG Cheng LI GuiCai LUO SheZhou XI XiaoHuan GAO Shuai ZENG HongCheng Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of Sciences University of Chinese Academy of Sciences national Satellite Meteorological Center China Meteorological Administration national Key Laboratory of remote sensing Institute of Remote Sensing and Digital EarthChinese Academy of Sciences Faculty of Forestry University of Toronto

The Geoscience Laser Altimeter System(GLAS)accurately detects the vertical structural information of a target within its laser spot and is a promising system for the inversion of structural features and other biophysical parameters of forest *** the GLAS footprints are discontinuously distributed with a relativity low density,continuous vegetation height distributions cannot be mapped with a high accuracy using GLAS data *** MODIS BRDF product provides more forest structural information than other optical remote sensing *** study aimed to map forest canopy heights over China from the GLAS and MODIS BRDF ***,the waveform characteristic parameters were extracted from the GLAS data by the method of wavelet analysis,and the terrain index was calculated using the ASTER GDEM ***,the model reducing the topographic influence was constructed from the waveform characteristic parameters and terrain ***,the final canopy height estimation model was constructed from the neural network combining the canopy height estimated with the GLAS point and the MODIS BRDF data,and applied to get the continuous canopy height map over ***,the map was validated by the measured data and the airborne Li DAR data,and the validation results indicated that forest canopy heights can be estimated with high accuracy from combined GLAS and MODIS data.

关键词： GLAS waveform decomposition terrain index canopy height model

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Using eye tracking to evaluate the usability of animated maps

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Science China Earth Sciences 2014年第3期57卷 512-522页

作者： DONG WeiHua LIAO Hua XU Fang LIU Zhao ZHANG ShaoBo State Key Laboratory of remote sensing Science Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities & School of Geography and Remote Sensing Science Beijing Normal University

Cartographic animation has been developed and widely used in geo-visualisation and many other areas in recent *** usability of animated maps is a key characteristic affecting map users’effectiveness and efficiency in accomplishing *** this paper,an eye tracking approach was proposed as a visual analytics method to evaluate the usability of animated maps by capturing participants’eye movement data and quantitatively analysing the accuracy(effectiveness)and response time(efficiency)of users’task *** the study,a set of animated traffic maps represented by three important visual variables(colour hue,size and frequency)was used for the usability *** experimental results showed that the usability of these three visual variables for cartographic animation affects the usability of animated ***,yellow,and aqua were found to convey map information more effectively than other colour *** was found to be more usable than colour hues for both animated maps and static *** was not found to be proportional to the playback rate of animated ***,the usability of the frequency,colour hue,and size was found to be related to the display’s *** hope that the analysis approach presented in this paper and the results of this study will be of help in the design of cartographic animation displays with better usability.

关键词： usability eye tracking approach animated maps visual variables

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An improved constraint method in optimal estimation of CO2 from GOSAT SWIR observations

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Science China Earth Sciences 2017年第2期60卷 286-296页

作者： ZOU MingMin CHEN LiangFu LI ShenShen FAN Meng TAO JinHua ZHANG Ying State Key Laboratory of remote sensing Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing 100101 China

We propose an algorithm that combines a pre-processing step applied to the a priori state vector prior to retrievals, with the modified damped Newton method （MDNM）, to improve convergence. The initial constraint vector pre-processing step updates the initial state vector prior to the retrievals if the algorithm detects that the initial state vector is far from the true state vector in extreme cases where there are CO2 emissions. The MDNM uses the Levenberg-Marquardt parameter ~,, which ensures a positive Hessian matrix, and a scale factor a, which adjusts the step size to optimize the stability of the convergence. While the algorithm iteratively searches for an optimized solution using observed spectral radiances, MDNM adjusts parameters ）, and a to achieve stable convergence. We present simulated retrieval samples to evaluate the performance of our algorithm and comparing it to existing methods. The standard deviation of our retrievals adding random noise was less than 3.8 ppmv. After pre-processing the initial estimate when it was far from the true value, the CO2 retrieval errors in the boundary layers were within 1.2 ppmv. We tested the MDNM algorithm＇s performance using GOSAT Llb data with cloud screening. Our preliminary validations comparing the results to TCCON FTS measurements showed that the average bias was less than 1.8 ppm and the correlation coefficient was approximately 0.88, which was larger than for the GOSAT L2 product.

关键词： Retrieve Optimal estimation CO2 GOSAT

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Scale effect of Planck's law over nonisothermal blackbody surface

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Science China(Technological Sciences) 1999年第6期42卷 652-656页

作者：李小文王锦地 A. H. Strahler Research Center for remote sensing and GIS Beijing Normal University Department of Geography and Center for remote sensing

Many physical laws, principles, models, measurement methods, etc., are applicable only to either a point on surface or a homogeneous surface. However, remote sensing deals with pixels which may range from meters to kilometers. Therefore scale effects of these laws and measurements are inevitable problems which must be faced. As an example, the spatial scale effect of Planck Law over nonisothermal blackbody surface is considered.

关键词： scale effect Planck’s law reciprocity.

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MFVNet: a deep adaptive fusion network with multiple field-of-views for remote sensing image semantic segmentation

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Science China(Information Sciences) 2023年第4期66卷 93-106页

作者： Yansheng LI Wei CHEN Xin HUANG Zhi GAO Siwei LI Tao HE Yongjun ZHANG School of remote sensing and Information Engineering Wuhan University

In recent years, the remote sensing image(RSI) semantic segmentation attracts increasing research interest due to its wide application. RSIs are difficult to be processed holistically on current GPU cards on account of their large field-of-views(FOVs). However, the prevailing practices such as downsampling and cropping will inevitably decrease the quality of semantic segmentation. To address this conflict,this paper proposes a new deep adaptive fusion network with multiple FOVs(MFVNet), which is specially designed for RSI semantic segmentation. Different from existing methods, MFVNet takes into consideration the differences among multiple FOVs. By pyramid sampling the RSI, we first obtain images on different scales with multiple FOVs. Images on the high scale with a large FOV can capture larger spatial contexts and complete object contours, while images on the low scale with a small FOV can keep the higher spatial resolution and more detailed information. Then scale-specific models are chosen to make the best predictions for all scales. Next, the output feature maps and score maps are aligned through the scale alignment module to overcome spatial misregistration among scales. Finally, the aligned score maps are fused with the help of adaptive weight maps generated by the adaptive fusion module, producing the fused prediction. The performance of MFVNet surpasses the previous state-of-the-art semantic segmentation models on three typical RSI datasets, demonstrating the effectiveness of the proposed MFVNet.

关键词： semantic segmentation remote sensing image (RSI) field-of-view (FOV) adaptive fusion convolutional neural network

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The atmospheric wet pool:definition and comparison with the oceanic warm pool

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Chinese Journal of Oceanology and Limnology 2008年第4期26卷 440-449页

作者：张彩云陈戈 program of Geospatial Information Sciences University of Texas at Dallas Ocean remote sensing Institute Ocean University of China

The oceanic warm pool （OWP） defined by sea surface temperature （SST） is known as the ＂heat reservoir＂ in the ocean. The warmest portion in the ocean mirrors the fact that the wettest region with the largest accumulation of water vapor （WV） in the atmosphere, termed atmospheric wet pool （AWP）, should be identified because of the well-known Clausius-Clapeyron relationship between SST and WV. In this study, we used 14-year simultaneous observations of WV and SST from January 1988 to December 2001 to define the AWP and investigate its coupling and co-variations with the OWE The joint examination of the area variations, centroid locations, and zonal migrations of the AWP and OWP lead to a number of interesting findings. The results hopefully can contribute to our understanding of the air-sea interaction in general and characterization of E1 Nifio/La Nifia events in particular.

关键词： OWP (The oceanic warm pool) AWP (atmospheric wet pool) air-sea interaction

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Boolean Operations on Conic Polygons

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Journal of Computer Science & Technology 2009年第3期24卷 568-577页

作者：龚咏喜刘瑜邬伦谢玉波 Institute of remote sensing and Geographic Information Systems Peking University State Key Laboratory of Information Engineer in Surveying Mapping and Remote SensingWuhan University

An algorithm for Boolean operations on conic polygons is proposed. Conic polygons are polygons consisting of conic segments or bounded conics with directions. Preliminaries of Boolean operations on general polygons are presented. In our algorithm, the intersection points and the topological relationships between two conic polygons are computed. Boundaries are obtained by tracking path and selecting uncrossed boundaries following rule tables to build resulting conic polygons. We define a set of rules for the intersection, union, and subtraction operations on conic polygons. The algorithm considers degeneration cases such as homology, complement, interior, and exterior. The algorithm is also evaluated and implemented.

关键词： Boolean operation conic polygon topological relationship

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High precision landing site mapping and rover localization for Chang'e-3 mission

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Science China(Physics,Mechanics & Astronomy) 2015年第1期58卷 139-149页

作者： LIU ZhaoQin DI KaiChang PENG Man WAN WenHui LIU Bin LI LiChun YU TianYi WANG BaoFeng ZHOU JianLiang CHEN HongMin State Key Laboratory of remote sensing Science Institute of Remote Sensing and Digital Earth (RADI) Chinese Academy of Sciences Beijing Aerospace Control Center (BACC)

This paper presents the comprehensive results of landing site topographic mapping and rover localization in Chang’e-3 ***-precision topographic products of the landing site with extremely high resolutions(up to 0.05 m)were generated from descent images and registered to CE-2 *** DEM and DOM with 0.02 m resolution were produced routinely at each waypoint along the rover *** lander location was determined to be(19.51256°W,44.11884°N,-2615.451 m)using a method of DOM *** order to reduce error accumulation caused by wheel slippage and IMU drift in dead reckoning,cross-site visual localization and DOM matching localization methods were developed to localize the rover at waypoints;the overall traveled distance from the lander is 114.8 m from cross-site visual localization and 111.2 m from DOM matching *** latter is of highest accuracy and has been verified using a LRO NAC image where the rover trajeactory is directly *** CE-3 mission operations,landing site mapping and rover localization products including DEMs and DOMs,traverse maps,vertical traverse profiles were generated timely to support teleoperation tasks such as obstacle avoidance and rover path planning.

关键词： Chang'e-3 Yutu rover landing site mapping rover localization descent camera navigation camera

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Deep neural network for remote-sensing image interpretation: status and perspectives

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national Science Review 2019年第6期6卷 1082-1086页

作者： Jiayi Li Xin Huang Jianya Gong School of remote sensing and Information Engineering Wuhan University State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan University

Deep neural networks(DNNs) refer to end-to-end mappings(i.e. from data to information) by stacking a large number of filters learned from massive samples. By courtesy of the comprehensive Earth observation platforms and convenient data access, remote-sensing practitioners are dealing with very large and ever-growing data volumes, which call for fast and transferrable machine-learning

关键词： status and perspectives image Deep neural network for remote-sensing image interpretation

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NIR-red spectral space based new method for soil moisture monitoring

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Science China Earth Sciences 2007年第2期50卷 283-289页

作者： GHULAN Abduwasit Institute of remote sensing and GIS Peking University

Drought is a complex natural disaster that occurs frequently. Soil moisture has been the main issue in remote monitoring of drought events as the most direct and important variable describing the drought. Spatio-temporal distribution and variation of soil moisture evidently affect surface evapotranspiration, agricultural water demand, etc. In this paper, a new simple method for soil moisture monitoring is de- veloped using near-infrared versus red (NIR-red) spectral reflectance space. First, NIR-red spectral reflectance space is established using atmospheric and geometric corrected ETM+ data, which is manifested by a triangle shape, in which different surface covers have similar spatial distribution rules. Next, the model of soil moisture monitoring by remote sensing (SMMRS) is developed on the basis of the distribution characteristics of soil moisture in the NIR-red spectral reflectance space. Then, the SMMRS model is validated by comparison with field measured soil moisture data at different depths. The results showed that satellite estimated soil moisture by SMMRS is highly accordant with field measured data at 5 cm soil depth and average soil moisture at 0―20 cm soil depths, correlation coef- ficients are 0.80 and 0.87, respectively. This paper concludes that, being simple and effective, the SMMRS model has great potential to estimate surface moisture conditions.

关键词： NIR-red spectral space soil moisture quantitative remote sensing soil drought remote monitoring of soil moisture

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