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1.
Contrast enhancement, one of the image processing techiques, is developed on the Multispectral Data Analysis System (MDAS) for enhancing the LANDSAT data. The purpose of image processing for enhancement is to improve the obscure objects data in the image to stand out more readily for good sensing to the human eye. It is observed on MDAS that some of the LANDSAT scenes when examined on the color display, give inadequate information for the required objective of interpretation. This is due to poor tonal contrast in the scene because of prevailing climatological conditions at the time of satellite pass over that area. Also, the LANDSAT data usually occupy a small subset of the total brightness range 0–127. To provide optimal contrast and variation for color compositing, contrast enhancement may by performed on the data before going to trie information processing (categolization) on the landsat scene. This paper describes the algorithms of parametric linear and non linear contrast enhancement techniques. A typical example to differentiate the degree of salinity in the soils was tested with the suggested algorithms and the results are tabulated in the form of photographs. The test area is selected from Haryana (frame no. 158-040 dated 2nd May, 1977) for testing the algorithms. The enhancement software developed on the MDAS stretches all the four Landsat bands and generates an output tape with the format similar to LANDSAT computer compatible tape (CCT). The stretched results of 5 and 7 bands are displayed in this paper. A false color composite which appears as on the color displya could also be generated from 4, 5 and 7 bands. The enhanced output was found to be useful for easily categorizing the data into various categories on MDAS.  相似文献   

2.
Geological studies in the area around Badami, Bijapur District, Karnataka, were carried out with the help of Landsat imagery and aerial photographs. The study are forms a part Kaladgi Basin which is located on the northernmost fringes of the exposed Dharwar Craton. Archaen Peninsular Gneiss and intrusive Granodiorite/Granites (≈Clospet Granite) form the basement for the Middle to Late Proterozoic Kaladgi Super Group sediments which are, in turn, overlain in the north by the Upper Cretaceous to Lower Eocene Deccan flood basalt lavas. Geological mapping of the study area and inferences about the structural setup were primarily based on interpretation of the remotely sensed data. The combined interpretative study of Landsat imagery and aerial photographs was instrumental in mapping of the lithostratigraphic units exposed in the study area along with the structures associated with them.  相似文献   

3.
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4.
Landsat imagery have been interpreted visually and under Additive Colour Viewer to interpret the regional geology and geomorphology in parts of Subarnarekha-Baitarani basin. The area lies south of Singhbhum shear zone and represents Precamrain shield. Important Simlipal ultrabasic volcanic complex of Orissa is included in the area. Although detailed map of the area is available, yet an attempt has been made to interpret the imagery for evaluating the results provided in comparison to the existing maps. Delineation of main lithological groups is possible. Having some data from the existing maps, lithoiogical boundary delineation of Mica Schist-Phyllite-Quartzite, Granites and Gneisses, Dhanjori Lava, Anorthosite-Gabbro Complex and Dolerite dykes, all of Precambrian age, has been done. Laterite and Quaternary sediments are also picked up. Lineament mapping has been carried out from imagery, which is difficult to map in the field. N--S and NNW-SSE lineament system is very prominent in Simlipal complex whereas in other parts NNW-SSE and NNE-SSW trends are common. The major fault plane running NNE-SSW in the area is responsible for the present-day configuration of Subarnarekha river. Identification of different geomorphological units is perhaps best done on imagery. Several geomorphic units like structural Hill, Denudational Hill, Pediment, Buried Pediment, Lateritic Clay Plain, Laterite upland, Terrace Plain etc have been mapped. Valley fills are wellpicked up from imagery. Hydrogeological potentiality of the different geologic and geomorphic units have been evaluated qualitatively. Ground water occurrence, movement and potentiality are mainly controlled by structural, geological and geomorphological set-up of the area. Buried Pediment, Laterite upland, Laterite clay plain and alluvial fills are the potential zones from the view point of ground water occurrences. Comparative study of the different Landsat bands and band-filter combinations under Additive Colour Viewer has been undertaken to find out the enhancement capability in delineating features. It is found that small scale geological and geomorphological maps can be prepared from Landsat imagery.  相似文献   

5.
Wasteland map (1∶100,000) of Rewasa catchment (Sikar district) has been prepared using aerial photographs and Landsat TM imagery. Thematic Mapper data were helpful in identifying the types of wastelands and details could be derived from the aerial photographs. The types of wastelands identified are sands, gullied land, salt affected areas, and barren rocky area. Depending upon the nature of wasteland, suitable rehabilitation measures like plantations, afforestation have been proposed.  相似文献   

6.
Target discrimination is the key step of automatic target detection in synthetic aperture radar (SAR) images. In this paper, a new algorithm, effective and robust feature sets for target discrimination in high resolution SAR images has been proposed. Two main steps in target discrimination of SAR images have been developed, the feature extraction based on Zernike moments (ZMs) having linear transformation invariance properties and the PSO based feature selection to select the optimal feature subset of Zernike moments for decreasing computational complexity of feature extraction step. The input regions of interest (ROIs) have been segmented and passed to a number of preprocessing stages such as histogram equalization, position and size normalization. Two groups of Zernike moments (shape and margin (intensity) characteristic) have been extracted from the preprocessed images and they have been applied to the feature selection step. Each group includes 34 moments with different orders and iterations. The selected moments have been applied to a SVM classifier. The proposed scheme has been tested on the MSTAR database. The Receiver Operational Characteristics (ROC) curve and the performance of proposed method using some measured data have been analyzed. Experimental results demonstrate the efficiency of the proposed approach in target discrimination of SAR imagery.  相似文献   

7.
To utilize the full potential of multispectral data acquired from aerial photographs/satellite imagery increased knowledge of the spectral reflectance characteristics of Landuse/Landcover features are required. Spectro-Radiometer was used to collect the spectral reflectance values in wavelength regions ranging from 0.48 to 0.96 u m, of some Landuse/Landcover features, in Roorkee and its surrounding areas. Spectral reflectance values, thus collected, were used to draw spectral reflectance curves of each feature separately and to determine the optimum wavelength regions for identifying each Landuse/Landcover feature. The wavelength regions, in which two dissimilar Landuse/Landcover features exhibit nearly same tonal variation in B&W aerial photographs/satellite imagery, were also determined from these curves.  相似文献   

8.
Multi-technique space geodetic analysis software has been developed which allows to combine data on the observation level. In addition to local tie information, site-wise common parameters, i.e., troposphere and clocks, can be estimated with this software. Thus, it will be discussed how common parameters have to be estimated and where biases/offsets need to be taken into account. To test such a novel concept, Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) data from the CONT11 campaign are being utilized. Since the VLBI baselines of this campaign extend over several thousands of kilometers, GPS data are processed in precise-point positioning mode and satellite orbits and clocks are kept fixed to the IGS final products. From the obtained results, it can be shown that the combination of space geodetic data on the observation level leads to a consistent improvement of station position repeatability as well as nuisance parameters like troposphere estimates. Furthermore, estimation of common parameters (troposphere or clocks) at co-located sites helps to improve the solution further and derive an utmost physically consistent model of the concerned parameters.  相似文献   

9.
In the vast alluvial plains of West Bengal and Orissa several deltaic plains exist, occurring in an off-lap sequence. These deltas were formed in the background of eustatic fluctuations during the Quaternary Period. They were built partly during rising sea level and pertly during stationary sea level stages. Landform analysis through aerial photographs as well as Landsat imagery interpretation, attested by field study, helped to establish the palaeogeomorphology of these Quaternary deltas. Possible mode of sedimentation during different phases of sea level fluctuations has been worked out  相似文献   

10.
Classification of Mobile Mapping LiDAR (Light Detection and Ranging) data is a challenge in the research community since the day when laser scanner system were integrated and mounted on vehicles for collection of 3D data in urban environment. The approach proposed here for classifying LiDAR data is analogous to the process followed for classifying data from satellite images. Pixel based and segmentation based methods have been employed in past for classifying images obtained from satellites. These methods were based on spectral properties of objects present in the images. But for Mobile mapping LiDAR data this approach has been applied and tested for the first time. The properties of this data are completely different from that of satellite images. So even if the basic approach remains the same, many changes have to be made in the entire classification process. The paper here aims to propose the basic procedure of using pixel-wise classification on dense 3D LiDAR data.  相似文献   

11.
Landsat MSS data in the form of BW imagery were used to generate Soil Map of Punjab convering an area of about 5 million ha. MSS bands 2 and 4 (L4) were interpreted singly and combined to form a compostie interpretetion map with which field check, was translated in terms of soils. The abstraction level attained was Great Groups of Soil Taxonomy. The distribution of soils of Punjab, with Aridisols in the SW through Inceptisols in the Central zone, to Alfisols in the NE sectors suggested a strong geographic bias in their evolution. The major soils of the aridic zone (SW sectors of the state) are: Camborthids, Calciorthids, Torripsamments and Torrifluvents and of the Ustic zone (Central Punjab) are Ustochrepts and Haplustalfs (the most productive soils of the State), Ustipsamments and Ustifluvents. The salt affected soils are found interspersed with these soils. In the udic zone (NE fringe), Hapludalfs, Eutrochrepts, Udifluvents, Udorthents and Hapludolls are the major soil formations. The soil map reveals that about one-third of the total area of the state suffers from various soil problems, such as soil salinity and sodicity, water logging, and soil erosion. For increasing agricultural production, these soils need to be brought under the plough. The study leads to conclude that for quick and precise macro level land use planning, the use of Landsat imagery is imperative.  相似文献   

12.
Deformations of radio telescopes used in geodetic and astrometric very long baseline interferometry (VLBI) observations belong to the class of systematic error sources which require correction in data analysis. In this paper we present a model for all path length variations in the geometrical optics of radio telescopes which are due to gravitational deformation. The Effelsberg 100 m radio telescope of the Max Planck Institute for Radio Astronomy, Bonn, Germany, has been surveyed by various terrestrial methods. Thus, all necessary information that is needed to model the path length variations is available. Additionally, a ray tracing program has been developed which uses as input the parameters of the measured deformations to produce an independent check of the theoretical model. In this program as well as in the theoretical model, the illumination function plays an important role because it serves as the weighting function for the individual path lengths depending on the distance from the optical axis. For the Effelsberg telescope, the biggest contribution to the total path length variations is the bending of the main beam located along the elevation axis which partly carries the weight of the paraboloid at its vertex. The difference in total path length is almost \(-\) 100 mm when comparing observations at 90 \(^\circ \) and at 0 \(^\circ \) elevation angle. The impact of the path length corrections is validated in a global VLBI analysis. The application of the correction model leads to a change in the vertical position of \(+120\)  mm. This is more than the maximum path length, but the effect can be explained by the shape of the correction function.  相似文献   

13.
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14.
CONT campaigns are 2-week campaigns of continuous VLBI observations. The IERS working group on combination at the observation level uses these campaigns to study such combinations. In this work, combinations of DORIS, GPS, SLR, and VLBI technique measurements are studied during CONT08. We present different results concerning the use of common zenith tropospheric delay (ZTD) during the combination. We compare the ZTD obtained separately using each individual technique data processing, the combined ZTD, and the ZTD derived from a meteorological model. This resulted in a high level of consistency between each of these ZTD at a sub-centimeter level, a consistency which especially depends on the number of observations per estimated ZTD and the humidity level in the troposphere. We noted that GPS provides the main information about the combined ZTD, the other techniques providing complementary information when a lack of GPS observations occurs.  相似文献   

15.
This paper presents a new algorithm for building extraction from LIDAR (Light Detection and Ranging) point cloud data on the basis of a marked point process based building model. In this building model, the positions and geometries of buildings are modeled by a point process and its marks, respectively. The geometric marks for buildings include their length, width, direction, height. By Bayesian paradigm, a posterior distribution for the marked point process conditional on the LIDAR point cloud data is obtained. The Reversible Jump Markov Chain Monte Carlo (RJMCMC) based scheme is designed to simulate the posterior distribution. Finally, Maximum A Posteriori (MAP) strategy is used to obtain the optimal building detection. The proposed algorithm is tested by a set of LIDAR point cloud data. The results show its efficiency in complex residential environments.  相似文献   

16.
The Airborne Laser Ranging System is a proposed multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the Earth's surface. Depending on the host aircraft and terrain characteristics, the system can interrogate hundreds of targets distributed over an area as large as 6×104 sq. kilometers in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a six hour flight. The precision of these range measurements is approximately ±1 cm. These measurements are then used in a procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.  相似文献   

17.
The general tendency of mapping groundwater resource using remote sensing and Geographic Information System (GIS) techniques involve assigning higher weightage to geomorphology. But this cannot be used as a thumb rule everywhere, especially an area where many ductile and brittle zones are prevalent. The influence of texture and structure of sheared rocks might play a control over retaining and permitting groundwater to flow. Attur valley is characterized by the presence of many shear zones and faults and hence the rocks are highly fissile within the shear zones. The present study tries to establish a new ranking and weightage scheme and hence a new spatial model for groundwater resource mapping in shear zone area like Attur Valley. This spatial model can be verified with field data such as water level data, pump test and resistivity data.  相似文献   

18.
The impact of forest management activities on the ability of forest ecosystems to sequester and store atmospheric carbon is of increasing scientific and social concern. This is because a quantitative understanding of how forest management enhances carbon storage is lacking in most forest management regimes. In this paper two forest regimes, government and community-managed, in Kayar Khola watershed, Chitwan, Nepal were evaluated based on field data, very high resolution (VHR) GeoEye-1 satellite image and airborne LiDAR data. Individual tree crowns were generated using multi-resolution segmentation, which was followed by two tree species classification (Shorea robusta and Other species). Species allometric equations were used in both forest regimes for above ground biomass (AGB) estimation, mapping and comparison. The image objects generated were classified per species and resulted in 70 and 82 % accuracy for community and government forests, respectively. Development of the relationship between crown projection area (CPA), height, and AGB resulted in accuracies of R2 range from 0.62 to 0.81, and RMSE range from 10 to 25 % for Shorea robusta and other species respectively. The average carbon stock was found to be 244 and 140 tC/ha for community and government forests respectively. The synergistic use of optical and LiDAR data has been successful in this study in understanding the forest management systems.  相似文献   

19.
Usefulness of Landsat imagery in discerning major arid zone soils has been studied. Results are based on analysis of Band 7 coverage and Band 5 and 7 for a limited area followed by a comparison of these with the known soil distribution as seen in Bikaner, Jodhpur and part of Jalore, Pali and Nagaur districts. Results show that at Band 7 the dominant course loamy Typic Camborthids in association with dunes could be recognised. Vegetation was found non-interfering though surface soil moisture variation of the period immediately following monsoon months (Sept.–Dec.) appeared to do so. Hardpan soils were identifiable largely by their associated features than by soil characteristics proper. Fine loamy typic Camborthids could not be recognised at series level and as a group also these could be identified only in post-monsoon period when the land is devoid of much of its vegetation cover. Saline areas could be recognised but those occurring in South-eastern tract were largely inseparable from adjoining shallow soils. For these, Band 5 image of monsoon months was quite satisfactory. For all other soils, Band 7 was better than Band 5. Though light brown sandy soils in association with dunes are the dominant formations, past evolutionary history and source rock variability have given considerable heterogeniety to the soil cover of the arid zone. Natural resource survey activity over the years has provided ground information for nearly 30 percent of Westren Rajasthan and this incidentally covers major soils of the area albeit with few exceptions. With the Landsat imagery now becoming accessible, it was thought befitting to see how far soil variations as recognised in the course of above surveys could be discerned from the Landsat. Some encouraging reports on the use of the Landsat or similar data in small cale soil mapping are available in literature (Kristof and Zachary, 1970; El-Baz, 1978; Everitt and Gerbermann 1977). In our own country also usefulness of this tool has been demonstrated by Krishnamurthy and Srinivanan (1973) and Hilwig (1975). Recently Bhandariet al; (1976) while working in northern part of arid zone have shown that soil salinity mapping could be attempted with the help of Landsat data.  相似文献   

20.
Wildland fires are common in rangelands worldwide. The potential for high-severity fires to affect long-term changes in rangelands is considerable, and for this reason assessing fire severity shortly after the fire is critical. Such assessments are typically carried out following Burned Area Emergency Response teams or similar protocols. These data can then be used by land managers to plan remediation and future land uses. To complement these procedures and explore fire severity modeling of sagebrush steppe rangelands, we compared models developed using (1) post-fire imagery only with (2) differenced imagery (pre-fire minus post-fire imagery). All models were developed from Classification Tree Analysis (CTA) techniques using Satellite Pour l'Observation de la Terre 5 (SPOT 5) imagery and Shuttle Radar Topography Mission (SRTM) elevation data. The results indicate that both techniques produced similar fire severity models (model agreement = 98.5%) and that little improvement in overall accuracy was gained by using differenced imagery (0.5%). We suggest the use of CTA models developed using only the post-fire imagery. The analyses and techniques described in this paper provide land managers with tools to better justify their recommendations and decisions following wildland fires in sagebrush steppe ecosystems and provide remote sensing scientists with information that will potentially improve future modeling efforts.  相似文献   

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