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Improved Cubemap model for 3D navigation in geo-virtual reality

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International Journal of Digital Earth 2015年第11期8卷 877-900页

作者： Qishen Duan Jianhua Gong Wenhang Li Shen Shen Rong Li state Key Laboratory of remote sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina Zhejiang&CAS application centre for Geoinformatics ZhejiangChina

Due to advances in rendering techniques and hardware capability,stereoscopic 3D(s3D)visualization is becoming increasingly common in daily ***,this does not change the fact that stereo effects and visual comfort depend greatly on how the related parameters are controlled during the production of the s3D *** geovirtual reality systems,which are important browsers for Digital Earth,the maintenance of these parameters is deeply related to the navigation ***,the navigation method in such systems requires special *** paper presents a new flying method based on a Cubemap *** method defines a Vehicle model and modifies the original Cubemap structure by adding a front view camera during the navigation;it allows the users to fly through a virtual geographic environment with automatic speed control,smooth collision resolution,and dynamic adjustment of the s3D-related parameters.A user test was conducted to compare this new method with the original method based on the Cubemap *** results show that the new method performs better than the former one for it provides a convenient interaction experience with improved stereoscopic effect,and diminishes visual discomfort.

关键词： virtual reality navigation Digital Earth virtual geographic environment

A routine operational backscattering coefficient regrouping algorithm for a HY-2A scatterometer

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Acta Oceanologica Sinica 2018年第3期37卷 111-116页

作者： ZOU Juhong LIN Mingsen ZOU Bin GUO Maohua ZHANG Yi Key Laboratory of Space Ocean remote sensing and application State Oceanic Administration National Satellite Ocean application Sevice State Oceanic Administration

The routine operational sigma0 regrouping method is proposed for a HY-2 A scatterometer（HSCAT） that maps time-ordered sigma0 s and related parameters into a subtrack aligned grid of wind vector cells（WVCs）. The regrouping method consists of two critical steps： ground grid generation and sigma0 resampling. The HSCAT uses subtrack swath coordinates, in which the nadir track of the satellite represents the center and the designated positions are specified in terms of a pair of along-track and cross-track coordinates. To calculate the subtrack coordinates for each sigma0, a ＂triangle marking＂ resampling method is developed. Three points, including the point of intersection, the center of a pulse footprint, and the origin of the subtrack coordinate system, form a right triangle; the length of the two right-angled sides is used to represent the cross-track and the along-track coordinates in the subtrack coordinate system. In addition, a nadir point interpolation correction is used to ensure the operation of the regrouping algorithm when the nadir point positional information is missing. To illustrate the ability of the proposed regrouping algorithm, the distribution of the WVC positions and wind vector retrieval results are analyzed, which show that the proposed regrouping algorithm meets the requirements for high-quality sea surface wind field retrieval.

关键词： regrouping HY-2A scatterometer backscattering coefficient

Assessing Reclamation Levels of Coastal Saline Lands with Integrated Stepwise Discriminant Analysis and Laboratory Hyperspectral Data

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Pedosphere 2006年第2期16卷 154-160页

作者： SHI Zhou CHENG Jie-Liang HUANG Ming-Xiang ZHOU Lian-Qing Institute of Agricultural remote sensing and Information System Zhejiang University Hangzhou 310029 （China）. state Key Laboratory of remote sensing Science Institute of Remote Sensing Application Chinese Academy of Sciences Beijing 100101 （China）

At different times over the past 30 years in Zhejiang Province, China, the coastal tidelands have been successively enclosed and reclaimed for agricultural land use. The purpose of this work was to evaluate whether laboratory hyperspectral data might be used to estimate the physicochemical characteristics of these reclaimed saline soils. A coastal region of Shangyu City (Zhejiang Province), which was grouped into four subzones according to reclamation history, was used as the study area, and soil samples were collected in each subzone. Physicochemical analyses showed that the soils were characterized by high electrical conductivity and sand content with low organic matter; the longer the saline lands had been reclaimed, the lower were the electrical conductivity and sand content and the higher the organic matter content. These changing trends of soil chemical and physical properties were found in laboratory reflectance spectra of soil samples and their first-order derivative curves. Stepwise discriminant analysis (SDA) identified six salient spectral bands at 488, 530, 670, 880, 1400, and 1900 nm. Using derived discriminant functions for saline lands with different historical years of reclamation, classification revealed an overall accuracy from a self-test of 86.6% and from cross-validation of 89.3%. Therefore, as opposed to time-consuming field investigations, this study suggested that remotely sensed hyperspectral data could serve as a promising measure to assess the reclamation levels of coastal saline lands.

关键词： hyperspectra reclamation remote sensing saline soil SDA

A stream-based Parasitic Model for implementing Mobile Digital Earth

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International Journal of Digital Earth 2014年第1期7卷 38-52页

作者： Wenhang Li Jianhua Gong Ping Yu Qishen Duan Yuling Zou state Key Laboratory of remote sensing Science Institute of Remote Sensing ApplicationsChinese Academy of SciencesBeijingChina Zhejiang&CAS application centre for Geoinformatics ZhejiangChina School of Management Xinxiang UniversityHenanChina

A Parasitic Model is proposed in this study for Digital Earth running on mobile phones through a mobile *** of mobile phones’limited capabilities in high-performance computing,rendering,storing,and networking(CRSN),these functions are accomplished by a superior host computer in this *** virtual scenes are compressed in a time-series as a data stream and are sent to the mobile phone through a mobile network,thus allowing Digital Earth to be operated on a mobile *** study examines a prototype and shows that a Mobile Digital Earth based on a Parasitic Model can achieve functionality beyond the mobile phone’s actual hardware capabilities and can reduce network *** results demonstrate quasi-real-time interactions,but with bandwidth increases in next-generation mobile networks such as 4G and 5G,there is potential for real-time interactions in the near future.

关键词： Parasitic Model Mobile Digital Earth adaptive transfer strategy mobile phone mobile network

The primary results of quantitative ocean color retrieval in China coastal area with CBERS CCD data

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Science China(Technological Sciences) 2005年第S2期48卷 161-176页

作者： TANG Junwu1,2, MA Chaofei1, NIU Shengli1, WANG Xiaomei1, SONG Qingjun1 & DING Jing1 1. National Satellite Ocean application Service, Beijing 100081, China 2. state Key Laboratory of remote sensing Science, Beijing 100010, China National statellite Ocean application Service Beijing China state Key Laboratory of remote sensing Science Beijing China

Using the techniques of quantitative ocean color sensing, the in-water ocean color algorithms for sediment and chlorophyll-a retrieval are established for CBERS-02 CCD broad spectral bands based on in situ data. The remote sensing reflectance of water is derived from CCD radiance data by a clear water atmospheric correction algorithm. Then, the sediment and chlorophyll-a concentrations are retrieved from CCD image. The sediment retrieval is quite satisfactory, but the chlorophyll-a retrieval is not so good because of the broadband width and low signal-to-noise ratio of the CCD camera.

关键词： CBERS-02 CCD ocean color sensing atmospheric correction retrieval of water constituents.

Coastal wind field retrieval from polarimetric synthetic aperture radar

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Acta Oceanologica Sinica 2014年第5期33卷 54-61页

作者： ZHANG Yi JIANG Xingwei SONG Qingtao LIN Mingsen XIE Xuetong National Satellite Ocean application Service State Oceanic Administration Key Laboratory of Space Ocean remote sensing and applications State Oceanic Administration

Coastal winds are strongly influenced by topology and discontinuity between land and sea surfaces. Wind assessment from remote sensing in such a complex area remains a challenge. Space-borne scatterometer does not provide any information about the coastal wind field, as the coarse spatial resolution hampers the radar backscattering. Synthetic aperture radar （SAR） with a high spatial resolution and all-weather observation abilities has become one of the most important tools for ocean wind retrieval, especially in the coastal area. Conventional methods of wind field retrieval from SAR, however, require wind direction as initial information, such as the wind direction from numerical weather prediction models （NWP）, which may not match the time of SAR image acquiring. Fortunately, the polarimetric observations of SAR enable independent wind retrieval from SAR images alone. In order to accurately measure coastal wind fields, this paper proposes a new method of using co-polarization backscattering coefficients from polarimetric SAR observations up to polarimetric correlation backscattering coefficients, which are acquired from the conjugate product of co-polarization backscatter and cross-polarization backscatter. Co-polarization backscattering coefficients and polarimetric correlation backscattering coefficients are obtained form Radarsat-2 single-look complex （SLC） *** maximum likelihood estimation is used to gain the initial results followed by the coarse spatial filtering and fine spatial filtering. Wind direction accuracy of the final inversion results is 10.67 with a wind speed accuracy of 0.32 m/s. Unlike previous methods, the methods described in this article utilize the SAR data itself to obtain the wind vectors and do not need external wind directional information. High spatial resolution and high accuracy are the most important features of the method described herein since the use of full polarimetric observations contains more information about the space

关键词： polarimetric synthetic aperture radar coastalwind field polarimetric correlation backscattering coefficients

An improved wind retrieval algorithm for the HY-2A scatterometer

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Chinese Journal of Oceanology and Limnology 2015年第5期33卷 1201-1209页

作者：王志雄赵朝方邹巨洪解学通张毅林明森 Ocean remote sensing Institute Ocean University of China National Satellite Ocean application Service State Oceanic Administration Guangzhou University

Since January 2012,the National Satellite Ocean application Service has released operational wind products from the HY-2A scatterometer(HY2-SCAT),using the maximum-likelihood estimation(MLE) method with a median filter. However,the quality of the winds retrieved from HY2-SCAT depends on the sub-satellite cross-track location,and poor azimuth separation in the nadir region causes particularly low-quality wind products in this region. However,an improved scheme,i.e.,a multiple solution scheme(MSS) with a two-dimensional variational analysis method(2DVAR),has been proposed by the Royal Netherlands Meteorological Institute to overcome such problems. The present study used the MSS in combination with a 2DVAR technique to retrieve wind data from HY2-SCAT observations. The parameter of the empirical probability function,used to indicate the probability of each ambiguous solution being the "true" wind,was estimated based on HY2-SCAT data,and the 2DVAR method used to remove ambiguity in the wind direction. A comparison between MSS and ECMWF winds showed larger deviations at both low wind speeds(below 4 m/s) and high wind speeds(above 17 m/s),whereas the wind direction exhibited lower bias and good stability,even at high wind speeds greater than 24 m/s. The two HY2-SCAT wind data sets,retrieved by the standard MLE and the MSS procedures were compared with buoy observations. The RMS error of wind speed and direction were 1.3 m/s and 17.4°,and 1.3 m/s and 24.0° for the MSS and MLE wind data,respectively,indicating that MSS wind data had better agreement with the buoy data. Furthermore,the distributions of wind fields for a case study of typhoon Soulik were compared,which showed that MSS winds were spatially more consistent and meteorologically better balanced than MLE winds.

关键词： HY-2A scatterometer wind retrieval maximum-likelihood estimation (MLE) multiple solution scheme (MSS) two-dimensional variational analysis method (2DVAR) typhoon Soulik

Graphics processing unit-based dynamic volume rendering for typhoons on a virtual globe

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International Journal of Digital Earth 2015年第6期8卷 431-450页

作者： Po Liu Jianhua Gong Miao Yu state Key Laboratory of remote sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Zhejiang-CAS application Center for Geoinformatics ZhejiangChina

Typhoons are usually accompanied by strong winds,heavy rain,storm surges and other disastrous events,and they are the most severe weather phenomena in the western part of the North Pacific *** is a key technology for analysing and presenting climate simulations and observations together with related social and ecological *** globes are a logical platform for visualising such geospatial data via the *** implement interactive visualisation of typhoon data within virtual globes,this study provides a 3D texture-mapping algorithm to render volume textures on a *** addition,a systematic framework is proposed in which a hierarchical octree-based multiresolution data structure is implemented to organise the large volume dataset,and a graphics processing unit-based dynamic interpolation approach is proposed to obtain a smooth ***,the structure is combined with a level of detail strategy to enable the rendering of dynamic volumetric data at an acceptable interactive frame *** demonstrate the capabilities of this framework,data for a simulated typhoon event were rendered in World Wind,an open-source virtual *** experimental results demonstrate that the application of the proposed strategies can result in an interactive visualisation performance that renders typhoon data on virtual globes.

关键词： typhoon GPU volume animation octree LOD virtual globes

Calibration of HY-2A satellite significant wave heights with in situ observation

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Acta Oceanologica Sinica 2016年第3期35卷 79-83页

作者： PENG Hailong LIN Mingsen College of Information Science and Engineering Ocean University of China Nation Satellite Ocean application Service State Oceanic Administration Key Laboratory of Space Ocean remote sensing and application State Oceanic Administration

Significant wave height（SWH） can be computed from the returning waveform of radar altimeter, this parameter is only raw estimates if it does not calibrate. But accurate calibration is important for all applications, especially for climate studies. HY-2a altimeter has been operational since April 2012 and its products are available to the scientific community. In this work, SWH data from HY-2A altimeters are calibrated against in situ buoy data from the National Data Buoy Center（NDBC）, Distinguished from previous calibration studies which generally regarded buoy data as ＂truth＂, the work of calibration for HY-2A altimeter wave data against in situ buoys was applied a more sophisticated statistical technique-the total least squares（TLS） method which can take into account errors in both variables. We present calibration results for HY-2A radar altimeter measurement of wave height against NDBC buoys. In addition, cross-calibration for HY-2A and Jason-2 wave data are talked over and the result is given.

关键词： total least squares NDBC buoys HY-2A altimeter significant wave height