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Wu B.,CAS Institute of Remote Sensing | Yang J.,CAS Institute of Remote Sensing | Zhao Z.,CAS Institute of Remote Sensing | Meng Y.,CAS Institute of Remote Sensing | And 5 more authors.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

Updating the existing land-use maps with remote sensing imagery has become a common method to produce the latest land-use database. An important step is to extract the changed information. In this paper, we propose a novel method to extract the changed parcels in land-use maps by using the holistic feature called 'Spatial Envelope,' which encodes each parcel without segmenting it into homogeneous objects or small regions. The holistic feature is based on the energy spectrum of the windowed Fourier transform (WFT) of each land-use parcel, which is ideal for scene categorization. Unlike the pixel-based change detection using the difference image (DI) leading to speckled results or object-based method which requires a complicated process to segment the land-use parcel into homogeneous land-cover objects, our parcel-based change detection treats each land-use parcel as an entirety by calculating the holistic feature for the former and latter parcels. Then, the distance between the corresponding former and latter parcels is compared against a threshold to select the changed parcels. Experiments have demonstrated that our procedure can extract the changed parcels with the overall accuracy of more than 92%. The performance of our procedure is reliable not only on the high-resolution (HR) images of the same sensor, but also on the images acquired by different sensors with the same or approximate spatial resolution. Comparative experiments have also proved that the holistic feature is better than conventional spectral and textural features in parcel-based change detection. © 2008-2012 IEEE. Source

Polpanich O.,Asian Institute of Technology | Davdai B.,National Remote Sensing Center | Hakari M.,Asian Institute of Technology | Samarakoon L.,Asian Institute of Technology
31st Asian Conference on Remote Sensing 2010, ACRS 2010

Climate change is causing persistent and prolonged drought in Mongolia, yet the impacts, especially damage to the nation's agricultural sector, remains poorly documented. As a negative result, agricultural production is vastly damaged. Soil moisture plays a crucial role in surface energy balances, runoff, potential drought and crop yield. It is important for the local government and people to take actions to agricultural production plan and protect their crop. This study aims to: 1) analyze the differences between global precipitation measurement (GPM) values and observing precipitation of Darkhan-Uul Aimag, 2) analyze the differences between soil moisture index (SMI) values retrieved from remotely sensed data and observing soil moisture data of the study area, and 3) delineate landuse/land cover map of the study area. An empirical method of detecting surface soil moisture condition using land surface temperature and vegetation index derived from MODIS data was used. About 50% of the SMI modeled by linear regression were well fitting in the observing soil moistures at 5 cm and 10 cm. Comparing 8-day SMI with observing rain rate data, it presented a good relationship, while LST responded a reversed pattern observing rain rate in 2007. The results facilitated the National Remote Sensing Center of Mongolia to correct SMI map of the country then transferred to country level for implementing the cultivation plan, while land use map was delivered to the local officials for daily-based management work. Source

Bo Z.,Beihang University | Jing Z.,National Remote Sensing Center | Wenwei D.,Beihang University | Longyang Y.,Beihang University
Advanced Materials Research

A novel method of analyzing the visibility of GNSS satellites in mountainous area is proposed by taking advantage of target area's digital elevation model (DEM) data and GNSS almanac. The key point is calculating the obstacle elevation on the basis of target points' visible range. Simulation results show that both different target points at the same time and same point at different time have different situation of visible satellites on the condition with or without obstacle. On the other hand, this method contributes lots to determine the distribution of pseudolites in mountainous area. © (2012) Trans Tech Publications, Switzerland. Source

Dung T.T.M.,National Remote Sensing Center | Tuan V.A.,Vietnam Academy of Science and Technology
31st Asian Conference on Remote Sensing 2010, ACRS 2010

Ha Noi has been expanded rapidly in the recent 30 years. During the time, the pattern of expansion is change time by time and it linked to the certain socio-economic situation of Viet Nam. However, using the remote sensing data which is available for Ha noi from 80 decades, the expansion pattern can be recognized. The most significant changes in land area, especially in sub-urban area which is the reduction of agricultural land besides the urban area of Ha Noi has also changed itself to the direction of increasing the building density. Estimation the change of Ha Noi in three categories: urban/resident; water; green-land from satellite images acquired from 1986 to 2007, we found the dynamic pattern of changes. The method used for change detection is visual interpretation based on the draft result of object-based classification. Source

Vu T.,National Remote Sensing Center | Nguyen D.,Hanoi University of Mining and Geology
33rd Asian Conference on Remote Sensing 2012, ACRS 2012

Application of remote sensing and GIS technologies in the field of natural hazard was developed in the last century and is continued until now. Remote sensing imagery supply information when natural hazard occurs (before, during and after) that will be valuable to monitor, manage, assess and estimate the economic losses. In the tropical region, during flooding time, cloud is covered almost so that the optical image would be not sharp. Radar imagery is selected to extract the water boundary and estimate the area flooded instead of optical image. The research on natural hazard is focused in different looking angles. Some research is concentrated in extracting the water boundary only; the other research is going further by applying the GIS analysis to estimate the economic losses due to that natural hazard. Some function in set of GIS tools was also used for computing area of land use types under water during flooding time. Those approaches are quickly and accurately. The United Nations Economic Commission for Latin America and the Caribbean (ECLAC) has extensive expertise in post-disaster impact assessment in 2004. Followed by ELAC methodology, evaluation of economic losses consists of three types as direct damage, indirect damage and secondary that information will help to consider where will be geographical regions or what will be social or economic sectors must be given priority in the rehabilitation and reconstruction process. Source

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