After forest fire or grass fire,the burned vegetation usually has a lower reflectance in the NIR-channel than they are healthy.The strong TOA (Top of Atmosphere) reflectance change can be detected in the NIR-channel and Red-channel of Optics Remote Sensing data over a vegetation layer.Extracting burned scar region is one key technique for calculating burned area of forest fire or grass fire by using satellite data.In this study,According to the records of many large forest fires or grass fires which have taken place in the experiment region in recent years,based on the spectral character analysis of typical objects in ENVISAT-MERIS (Medium Resolution maging Spectrometer Instrument) images,methodology of burned scar mapping has been studied.The extracting results have been compared by using image processing method,vegetation index method and object image analysis method.It shows that the results can be used directly to evaluate the burned scar area.It's an effective quantificational method by using object image analysis to extract burned scar region.
This study aimed to search for the estimation model for suspended sediment concentration (SSC) using Moderate\|resolution Imaging Spectroradiometer (MODIS) of medium-resolution data and using hyperspectal reflectance data to identify the most sensitive hyperspectral band. In this study, the utility of MOIDS data and hyperspectral data for analyzing turbid water was examined in Poyang Lake. The spectral characteristics of water surface with high SSC were determined by hyperspectral measurements during the field survey in seven sample points. The regression analysis using hyperspectral data was the basis of the approach using remote sensing data. A strong linear relationship (R2 = 0.91; n = 25) was established between band 1 MODIS Terra 250 m reflectance and in situ measurements of SSC acquired from different environments in Poyang Lake Basin. The moderate resolution of MODIS 250 m data and the operating characteristics of the instrument provide data well suited for assessing temporal and spatial patterns of SSC in Poyang Lake. Finally, the istorical images were analysed using the calibrated model to map the suspended sediments concentrations. Based on monitoring the sequence of suspended sediment concentration during the flood season, the configuration of the back flows of water from Yangtze River can be observed.
Remote sensing was used as a powerful approach to estimate and supervise net primary productivity of terrestrial vegetation, for it is free from hard field works and realizes the estimation of NPP in a large region. A new vegetation index was developed based on pattern decomposition method and light-use efficiency model was taken to estimate NPP of Wuhan (mostly subtropical evergreen -deciduous forests) using Landsat\|ETM data. The result was compared with the ones obtained by LUE model and other field investigation.
With complicated natural conditions, multiplicity of crop structure, small and dispersive distribution of parcel, the accuracy of images with moderate and lower resolution can't meet the acquisition of crop yield forecasting. With improvement of new sensors of high resolution, remote sensing imagery of high resolution can provide more abundant information such as texture, hue and so on. However, the current object-oriented classification approaches are not mature, which have too much thresholds to be set and more complicated and difficult to be used commonly. Therefore, combining QuickBird high spatial resolution satellite imagery with the field investigation data as mainly auxiliary information as well as using the pixel-oriented maximum likelihood method, crop planting area was obtained step by step, applying the principle of multi-scale information extraction,a test was set in Mianyang, Sichuan province.The result shows that the accuracy of crop classification is fairly exciting.
Based on the Shuangliu County TM images and CBERS remotely sensed images, the image correcting, enhancing and fusion was studied, using RS and GIS technology. Combining auto-classification with visual interpreting, the database of land use/cover change in the year of 1996-2006 was established and analyzed. And the past and present situation of land use was discussed.
Object-oriented information extraction technology compared with the pixel-based classification method is suitable for classification of high resolution remotely sensed images. Object-oriented image analysis has two key technologies, multi-scale image segmentation and classification technologies based segmentation. Urban area of Huairou was selected as study area, and the purpose is to extract information from QuickBird image using above approach. The conclusions are:①“pepper and salt”noises are discarded;②84.82% overall accuracy is achieved while only 73.87% is achieved with traditional pixel-based method. Furthermore, precision of each kind of object information was also improved, particularly for grass, roads and building shadows.
8-day composite MODIS temperature product MOD11A2 and 16-day composite MODIS NDVI product MOD13A2 were combined to construct Ts/NDVI space and the TVDI(Temperature Vegetation Dryness Index) was obtained.Every 16-day soil moisture in 40cm depth in different seasons in Yizheng was retrieved by TVDI.When compared with the soil moisture in 40cm depth measured simultaneously with satellite in the field,the mean error was 11.83% and minimum error reached 4.30%.The soil moisture distribution map shows that there were two high-value soil moisture areas,located in the Yangtze River alluvial plains in the southern part of Yizheng and the corner plains in the northwest part of Yizheng.The greater of the mean soil moisture is,the smaller of the difference between its high value and low value in the region .
Method of Slope to extract water from background and Model of Double Absorption Depth to distinguish
sea water and land water were put forward, based on comparative analysis of the spectral characteristics of major
objects such as water bodies, soil and vegetation etc. and the comparative analysis of the spectral characteristics of sea water and land water. Using this method to extract water bodies from background will improve the accuracy
and can not be affected by shadow. Water bodies were extracted from background, at the same time, sea water and
land water were distinguished based on this method and model in Liaodong Bay, the result shows that it can well
accord with the fact. This paper provides a new method and technique for classification and extraction of water
bodies' information to take a better management of water resources, flood monitoring, seawater intrusion monito-
ring and the monitoring of the river's impact on seawater in estuaries.
The normalized difference vegetation index (NDVI) is one of key indicator of land vegetation cover feature. Taking the inversion NDVI serial images of MODIS data as an example, this paper analyzes the changes of vegetation growth trend and the change intensity of the NDVI from 2003 to 2006 in Shihezi municipality, Xinjiang province by the change vector analysis method. The distribution of vegetation cover changes intensity was obtained. The results show that there is no great change within past four years.
The temporal and spatial landscape changes of the wetland at Shuangtaihekou area were studied
using one Landsat ETM data in 2000 and one CBERS-02 CCD data in 2005,based on remote sensing and
Geographic Information System.The landscape types of the two data are extracted and the changes are ana-
lyzed by landscape type transformation matrix,at the same time,the transformation trend during these two
periods is also predicted by Markov model.The result shows that the transformation of the wetland from
natural wetland to artificial wetland is obvious,and the area of the wetland tends to shrink.
It is the basis for river management, development and remediation to extract and acquire accurate water
information using remote sensing and GIS techniques. A net river region of Foshan in the Pearl River Delta was se-
lected as study area. After analyzing the spectral characteristics of river water bodies and other objects in Landsat
TM images, several water indices models were established. Among these models, ratio water indices model(RWI)
proved to be the best one. Then, the results of RWI were taken to get water thematic images by using special clus-
tering analysis method, as a result, the main water information were extracted from other spectrums. In addition
to these, the missing small rivers were checked out by the shape index. Accurate assessment indicated that this
technique is feasible and effective, furthermore, accuracy can reach 93.7%. That is, the method has important ac-
ademic and practical significance,especial for the water information of net river region, where the river web is more
complicated and human interference is intense.
Two SPOT5 imageries of Nansihu Lake (middle of June,2006) were interpreted to classify the land cover,using ERDAS Imagine and ArcView.As the fishpond and the open water-body were difficult to be distinguished,unsupervised classification and manual interpreting were used .The accuracy of interpretation classification was 83.3% after checking.The land cover classification types were mapped and the area of each type was calculated.The overall area of Nansihu Lake is 1206.9 km2,only 45.54% belongs to open water.Other lands are covered with wetland vegetation,fishpond,farmland and forests,with proportions of 21.06%,15.60%,11.23% and 5.66%,respectively.The land cover characteristics were also analyzed based on the map.To protect the ecological system of the lake,making land by separating the lake should be prohibited and the aquatic agriculture should be regulated through government regulations.
Changes in vegetation distribution of Loess Plateau during 1998~2005 are discussed in this paper
based on SPOT4/VEGETATION data. The ratio of NDVI and the annual mean NDVI were used as the indices to show the dynamic changes. The conclusion is that those changes have been greatly enhanced during the past few years. The vegetation cover had decreased since 1998, however, after 2001 it has been increased significantly, for the Grain for Green Project, even though a little rebound in 2004. Both growth rate and growth period have a great impact on NDVI. Changes in vegetation distribution have taken place in so many different areas. This phenomenon is caused by a variety of factors such as farming, urban planning and weather changing.
SAR images registration is an important step in SAR interferometry technology, a sub-pixel accuracy of the registration step is necessary to obtain a phase interferogram that truly reflects the elevation or deformation of the target on the ground. This paper introduces the basic conception of external DEM based SAR image registration method and gives an analytical expression of sensitivity analysis in respect of DEM error effect. The paper realizes the processing flow of SAR registration method and implements the subpixel precision registration of SAR images. The ERS datum is used as validation, and the results show that 1% pixels registration accuracy can be archieved by using precise orbit and SRTM as external DEM, this image registration method is especially useful in the situation of big temporal baseline and large geometric baseline.
A calibration method of receiving in-phase error and amplitude error is brought out,which overlap
many 1?4noise distribution networks on a closed loop to achieve 1?10 noise distribution network.The
method's robust is also analyzed,the result shows in-phase remain error is less than 2.3 degree when the
unseparated in-phase error is 1 degree,quadrature error is 0.5 degree and random error is 2%, which indi-
cates the calibration overlapped on a closed loop is prior to the opened one.
The object spectral is seriously disturbed by the topographic effects in mountainous area, which
severely affected the object recognition and classification. Topographic correction not only improves the
classification accuracy but is a prerequisite in any quantitative remote sensing with high preciseness approach. CIVCO model is an experiential and applied model, based on the statistics. It is complex and arduous to select sunlit and shade, and the correct result is affected by slope. In this paper, we use sun azimuth and aspect to simplify the selection of sunlit and shade, grade the gradient and compute the correction coefficient. Based on the improved model, the experiment using a Landsat TM image of the Qilian Mountains in the upriver area of Heihe and the corresponding DEM data proved that the improved method get better results than the C and CIVCO model.
Look-up table method is applied to test the match between FY-3A VIRR(Visible and InfraRed
Radiometer)cloud mask and IRAS(Infrared Atmospheric Sounder).Therefore,the mapped cloud mask has
the same spatial resolution as IRAS which is helpful for the retrievement of atmospheric temperature and
humidity profiles from IRAS.The simulated VIRR cloud mask and IRAS data are used and the matched re-
sult is compared with original VIRR cloud mask.
Radar is the important means for land and polar glacier depth sounding. High-resolution imaging
glacier penetrating radar (HRI-GPR) works at VHF band. A dual-channel receiver is introduced for improving the performance of HRI-GPR system. In order to reduce the complexity of the receiver, an immediate I.F. sampling technology is adopted for signal acquisition and the pulse compression in digital domain is done in the receiver.The selection of sampling frequency and implementation method of pulse compression are presented in this paper.The designed receiver is successfully applied in our HRI-GPR system.
This paper systemically introduced the key technology and systematic structure of Integration of
Remote Sensing Image and Basic Thematic Maps on Web.The selected study objects are basic thematic
maps of Xilinguole and remote sensing images of Zhenglan banner. Modern information technology and the
principle of WebGIS are attempted to design the experimental software by applying the technology of JAVA applet,and realize the system of remote sensing image and several thematic maps translucent overlayed
on web.
The paper introduces the latest progress of the bidirectional reflectance semi-empirical model and physical model in theoretical research and analyses the advantages and disadvantages of each model. Meanwhile, summarized the current development of the model inversion strategy and method. Furthermore,discussed the existing problems and the solutions in laboratory, theory as well as in applications.
Drought occurs frequently in most regions of China and seriously impacts the agriculture. Remote
sensing is the efficient method which can dynamic monitor drought at a great range of scale. This paper reviewed the current remote sensing approaches in drought monitoring and describes several methods for effective drought monitoring of large land areas, including thermal inertia, evapotranspiration and the vegetation index; Furthermore,the vegetation index includes anomaly vegetation index, vegetation condition index, vegetation index difference, vegetation supplication water index and temperature vegetation dryness index and so on. Dominances and limitations of these methods are discussed. As the application of drought mechanism combining with MODIS data,drought will be monitored in a wider scale in the future.
