Through two years, rice farm experiment under the different nitrogenous level, by using ASD- FieldSpec spectral data of late rice in whole developing time have been collected. According to satellite sensors, spectral channels and spectral regions that have physical content, variable groups of multiple spectra can be constructed. Using linear and non-linear regression methods, the estimated models about LAI of rice have been built on the basis of the experiment data in 1999 acted as train sample and their precision has been evaluated and tested on the basis of the experiment data in 2000. In the multiple spectra variables,the vegetation indices are better than wide wave band variables and RVI is better than NDVI and the precision of non-linear regression methods is higher than one of linear regression methods in estimated LAI models. In all models of estimating LAI, the logarithm model of SPOT3/SPOT2 that is independent is the best one, because its root mean square error and relative error were least.
Taking Bohai Sea as a demonstration area, this paper studies the applications of CBERS-1 imagery in the monitoring of pollutant diffusion, oil development, and coastal environment etc. According to the application demands and the imagery quality, the authors study the image processing methods to enhance the useful information and apply them in the analysis. In the processed image of Laizhou Bay, the river output pollution may be seen clearly. In the Liaohe river mouth, we analyzed the diffusion of into-sea pollutant combining with the field inorganic N data and CCD image. The oil pipes can be seen distinctly in the image, so the CBERS-1 CCD can be used in the oil development and monitoring. The resolution of the CCD image can meet the demand of the aquiculture pollution monitoring. The aquiculture area can be measured from the image, and the COD quantity may be also calculated accordingly. This research shows that the CBERS-1 data has good application prospective in the aspects mentioned above. The monitoring period will be shortened and the cost also be reduced by combining CBERS-1 data with other remotely sensed and in situ data.
Gudong oil field provides a basis for the economic development of local government, and pollutes the environment at the same time. Comparison with 235.56×10-6in 1986, oil content in soil (236.40× 10-6) increases lightly at Gudong oil field now. At the same time environmental effects associated with oil field development are studied with multi-temporal Landsat TM data at Gudong oil field during the latest twenty years. It shows that environment was destroyed quickly during the beginning time. Then these effects worked up to the dynamic balance after about ten years, development.
This paper presents a statistical analysis on the feasibility of estimating leaf C/N ratio with hyperspectral remote sensing data. Correlation analysis on the samples of NASA ACCP data set shows that the changes of correlation coefficients with wavelengths in 3 different forest sites are similar. Correlation coefficients of C/N ratio and reciprocal of nitrogen concentration with spectra from 400nm to 2500nm are compared respectively. Their correlation curves fit each other so well, which reveals a shortcut in C/N ratio researches by using the methods and validated results in previous nitrogen researches. Stepwise multiple linear regressions are employed on the 3 sites respectively. C/N ratio, nitrogen concentration and reciprocal of nitrogen concentration are calculated as dependent variables respectively, and the apparent absorption spectra at different wavelengths are calculated as independent variables. Almost all adjusted R2of the3 sites are more than 0.8 with not more than 4 wavelengths being selected. The satisfactory statistical results prove that estimating leaf C/N ratio with hyperspectral remote sensing data is feasible.
Based on remote sensing and GIS technology, a mathematical method to verify the precision of remote sensing land use classification was introduced. It was used to check the first grade classification result of land use of Dingxi County in 2000. The precision is relatively high. The variance for correctly classifying the areas of man-use-land is 0.000000027, of agricultural land is 0.000021871, of natural and seminatural vegetation is 0.000005427, of water body is 0, and of unused land is 0.000009201. The total classification precision is 0.9791. The verification result reflects the reliability of using TM image as a main resource for land use investigation in complicated region.
Quantitative morphologic analysis has been the new stage of morphology development since 1950' s. Quantitative morphologic analysis may be used to study three-dimensional surface form in the round, and may distill all kind of morphological character parameters and basic topography elements. Data distilled by the method are not only the most basic physical geographic elements, but also the most influential physical elements to the human' s everyday activity. Quantitative morphologic analysis provides data support for ecological study, agricultural plan, soil and water erosion and building etc. The paper takes the Yongwen River basin as study area and creates special maps of Yongwen River basin in slope, aspect,
elevation, rolling tolerance and virtual topography based on Geographic Information System and gets precise morphologic factors data. Then the morphological factors data and surface substance are analyzed. Finally the advantages and disadvantages of the method are evaluated.
This paper discussed mainly the rockslide of Wanzhou which is a upland city in the reservoir of Three Gorges. By analyzing TM remote sensing image with the method of principal component analysis and combining GIS technology, we found that the place where rockslide was taken place all focus on the strata nearby the borderline between J2s and J3s. Obviously, this hazard must be highly related to the strata. So the regulation of distribute for rockslide hazard is clear.
A new method for extracting clay-alteration information from ETM images was applied in three main steps. First, based on the linear unmixing model of MSA, this paper managed to get the vegetation abundance of the study area; second, making some supplements to the basic linear model of MSA, a new multi-band data set was reconstructed containing no vegetation information; third, get the clay-alteration information by making TM5/TM7 ratio image in which the shadow information was dramatically compressed. Field survey and other information have shown that the practice of this paper is right and can be adopted to extract thematic information for such areas as with medium vegetation cover. Compared with the methods mainly based on PCA～ratio combination, this method is more effective and offers a more universal frame to follow to extract clay-alteration information in medium vegetation areas.
Grassland degradation is a key factor of eco-environmental deterioration and more and more attention is paid to grassland degradation. As we know, there are wide land and few people in Tibet. The author applied RS technology to the grassland degradation assessment in Naqu area and got a good result.The good correlativity between grassland coverage got in field study and NDVI calculated with RS images was used in the supervised classification. Finally we assessed the situation of grassland degradation according to its assessment index system, and drew the map of grassland degradation as well. Studied results showed that the grassland degradation is very serious, and the grassland degradation area in Naqu area is 13 650 900 hm2which accounts for 48.8% of the grassland area in Naqu. The light degradation area accounts for 59.3%, the middle one 29.2%, and the serious one 11.5%.
A method of area target' s raw data simulation of spaceborne SAR based on elliptical orbit is presented. Foremost, based on models of satellite with elliptical orbit and targets with rotation of the earth,the distance between the satellite platform and target can be attained, which is compared with the one obtained by other models. The effect of the difference between the elliptical orbit model and circle orbit model on the azimuth compression is analyzed. An optimum method based on polynomial model is brought out.Then, the method and whole procedure of simulating area target' s raw data are described. The detailed description of math model of area target' s echoes is given first. Following are the steps of simulating raw data of area target. Lastly, the image of the compressed raw data is illustrated and analyzed. The validity of compression algorithm is proved by the compressed result of single point target. After the comparison between the compressed image of raw data simulated and the original image, the conclusion can be reached that this paper' s method of simulating raw data of area target is right.
During designing of spatial database with integrated architecture, we are always related to non-structural problems. At the base of summarizing two techniques overcoming this problems which are object-oriented technique and middle-piece technique, author analyzed standardization, memory structure and layer management of spatial data engine in the commercial middle-piece, gave the example of spatial data engine and put forward the problems which are starved for solved.
Component GIS (ComGIS), a new technology based on COM(Component Object Model),is a mainstream in GIS technology. Recently,this technology develops so fast that more and more ComGIS software booms.GeoMedia,the product of Intergraph, is used widely because of its strong spatial analysis ability.This paper thoroughly reviews GeoMedia' s searching and provides how to get records,implements the problem of searching using Visual C++ and ComGIS software.It may be believed that ComGIS will grow to be an important branch of Earth System Science.Geomedia is to be used widly and plays an important role in Geographic Information Systems. The study helps to understand developing core GIS' s function using VC and ComGIS.
The concept of hyperspectral remote sensing, the characteristics of the hyperspectral data, the main types of the imaging spectrometer, data processing software and spectral library construction are dwelled on in this paper. On the basis of that, the status in quo of the applications of the airborne hyperspectral remote sensing on ocean, environment and resource prospecting, monitoring of vegetation and zoology is summarized briefly. The prospect of hyperspectral remote sensing is given in the end.
