Short-Term and Long-Term Geomorphological dynamics of mangalore spits using IRS-1A/1C data

The city of Mangalore is situated at the confluence of rivers Gurpur and Netravati. Two spits are formed in this area, i.e., northern spit of “Bengre” and the southern spit of “Ullal” as the rivers flow close and parallel to the seashore for some distance. The spits have been subjected to constant geomorphological changes in length, width, position, accretion and erosion patterns etc., for the past several decades. A seawall was constructed in 1984 around the tip of Bengre spit and another one along the shoreline of Ullal spit in 1987, by the Government of Karnataka in order to prevent the spits from being eroded. Two breakwaters were also constructed in 1992 near the estuarine mouth as part of the development of old Mangalore Port. The paper presents the results of a study undertaken to identify the geomorphologic changes that occurred in the area, using 1RS-1A/1C data for the years of 1988, 1994. 1996. The study clearly demonstrated that the 1RS data could be effectively utilized for monitoring the geodynamics of an area. It was observed that the spits were highly unstable earlier. However, the construction of seawalls was helpful in arresting the migration of the estuarine mouth and in stabilizing the spits against coastal erosion.     

Liquefaction Identification Using IRS-1D Temporal Indices Data

One of the major after effect of Bhuj Earthquake which occurred on January 26, 2001 was wide spread appearance of liquefaction of soil in the Rann of Kachchh and the coastal areas of Kandla port covering an area of more than tens of thousands of kilometers. Remote sensing data products allow us to explore the land surface parameters at different spatial scales. In this work, an attempt has been made to identify the liquefied soil area using conventional indices from IRS-1D temporal images. The same has been investigated and compared with Class Based Sensor Independent (CBSI) spectral indices, while applying fuzzy based noise classification as soft computing approach using supervised classification. Seven spectral indices have been investigated to identify liquefied soil areas using temporal multi-spectral images. The result shows that the temporal variations can be accounted by using appropriate remote sensing based spectral indices. It is found that CBSI based TNDVI using temporal data yields the best results for identification of liquefied soil areas, while CBSI based SR gives best results for water body identification.     

Results on potential use of simulated IRS-1C WiFS data for crop monitoring

Some of the basic requirements for cropping system analysis are updated information on crops grown, their phenological behaviour, method and duration of establishment and harvest, inter and intra crop variability, sequential cropping patterns. The next generation Indian Remote Sensing Satellite with high repeat cycle opens new possibility of crop surveys to derive such information. In this study, an attempt has been made to analyse cropping system at district level using simulated IRS-1C Wide Field Sensor (WiFS) data. Data acquired for nineteen dates during 1992–93 season for Bardhaman district, West Bengal has been used. It was feasible to derive accurate information on cropping pattern, crop rotation, crop duration, progress of harvest, crop growth profiles and annual crop acreage using multidate data. It was observed that even a seven to eight day interval of data acquisition during critical growth periods significantly affected classification and identification accuracy.     

Delineation of surface waterlogged areas in parts of bihar using IRS-1C LISS-III data

Pre-monsoon and post-monsoon surface waterlogged areas were delineated using satellite remote sensing data for Muzaffarpur, Vaishali and Saran districts of North Bihar. Digital data of IRS-1C LISS-III sensor acquired on December 7, 1998 and April 6, 1999 were analyzed using digital image processing software-ERDAS Imagine 8.3.1. The surface waterlogged areas were delineated using modeling technique which is the most advanced and accurate method. Using the modeling technique, a pixel is classified as water if the digital number (DN) value of its Near Infra Red (NIR) band is less than the DN value of the Red band and the Green band, and the Normalized Difference Water Index (NDWI) is greater than or equal to 0.32. The pre-monsoon surface waterlogged areas are found to be 14.02, 23.61 and 9.61 km² while the post-monsoon surface waterlogged areas are found to be 231.83, 118.19 and 176.06 km² for Muzaffarpur, Vaishali and Saran districts, respectively. Also, land use/land cover maps were prepared.     

National Wheat Acreage Estimation for 1995-96 Using Multi-Date IRS-1C WiFS Data

I he aim of the piesent study was to suggest an approach for national level acreage estimation for wheat using satellite remote sensing data and demonstrate its perfromantee Multi-date moderate resolution (188 m) IRS-IC WiFS data sets were used as the core data Sampie segment approach with stratified random sampling was used for the data analysis For making meaningful comparisons over time, multi-date sets were geometncally registered and radiometrically normalised by extracting pseudo-invariant Features and performing regression analysis on the digital numbers of such features The corrected multi-temporal data sets were used in hierarchical classification scheme. The results of this exercise are presented. It appeals that there is an overestimatoin of wheat acreage The sampling effieieney was also low, indicating need to improve sampling strategy Some of the problems encountered and the corrections planned to overcome them are also discussed     

Evaluation of simulated IRS-1C WiFS data for concurrent monitoring of command areas at disaggregated level

Data of Wide Field Sensor (WiFS) to go onboard Indian Remote Sensing Satellite, IRS-1C, in December 1995, is simulated mainly from IRS IB LISS I data of Bhadra command area, Karnataka (India) during 1993–94 summer season, to evaluate its capability in concurrent monitoring of irrigated crops at disaggregated level Crop area, crop-growth profiles of homogeneous crops like paddy, as obtained from both simulated WiFS data and LISS I data are very close for almost all the distributary commands of Bhadra project Though non-paddy-crop groups could also be classified satisfactorily, the Workability with small-extent-individual crops like groundnut, garden and sugarcane is found to be less due to coarse resolution of WiFS data and hence the individual crops could not be separated out. This study proves the potential of WiFS in concurrent monitoring of fairly-large-extent irrigated crops at distributary level. The basic feasibility of WiFS had been established in an earlier work at broad level and this study demonstrates the feasibility of information extraction at distributary command level from WiFS data.     

Burnt area mapping of Bandipur National Park,India using IRS 1C/1D LISS III data

The Bandipur National Park situated in the Western Ghats of Karnataka State, is one of the biodiversity hotspots of the world. During recent years, this park has witnessed repeated fires, affecting considerable areas under vegetation. The temporal satellite data from 1997 to 2006 have been analyzed to map the burnt areas using Remote Sensing (RS) and Geographic Information System (GIS) techniques. The vegetation cover is moist deciduous, dry deciduous, scrub forests and teak plantation. Information on extent of the burnt areas and the type of vegetation affected were derived forest range-wise. The fire prone regions have been identified by integrating vegetation type/density, road and settlement network and past history of forest fire occurrence, by assigning subjective weightage according to their fire-inducing capability or their sensitivity to fire. Comparison between each temporal dataset in terms of the extent of burnt area was also carried out to interpret fire incidence pattern. Three categories of fire risk regions such as Low, Moderate and High fire intensity zones were identified and it was found that almost 40% of the study area falls under low risk zone. An evaluation of the existing fire management systems and the implication of fire prevention programmes has been discussed, besides an assessment of causal factors for fire incidence in the park.     

Application of digital elevation model and orthoimages derived from IRS-1C pan stereo data in monitoring variations in glacial dimensions

An attempt has been made to study variations in the glacier extent over a period of time using digital elevation model (DEM) and orthoimages derived from IRS-1C PAN stereo pairs of 1997–98 and topographical map surveyed during 1962–63. DEM and orthoimages have been generated using integrated software developed for processing of IRSIC/ID panchromatic stereo data using the softcopy photogrammetric workstation. Case studies of two glaciers, i.e. the Janapa garang and Shaune garang glaciers of the Basapa basin, a sub-basin of Satluj River in India, have been presented here. Generation of DEM has been followed by the estimation of its accuracy. PAN images were interpreted for identification of the snout of the glaciers. The geographical locations of the snouts on the images were compared with the location as mapped on the topographical map of the study area. To verify satellite observations, field investigations were carried out at Shaune garang glacier area. The Janapa garang and the Shaune garang are observed to have retreat of 596m and 923 m respectively. Reduction in the thickness of ice in the deglaciated part of the Shaune garang glacier was estimated on the basis of change in the elevations of the glacial surface from 1963 to 1998.     

Spectral characteristics of sensors onboard IRS-1D and P6 satellites: Estimation and their influence on surface reflectance and NDVI

This paper reports the results of a modeling study carried out with two objectives, (1) to estimate and compare effective spectral characteristics (central wavelength, bandwidth and bandpass exo-atmospheric solar irradiance E_o) of various spectral channels of LISS-III, WiFS, LISS-III*, LISS-IV and AWiFS onboard Indian Remote Sensing Satellites IRS-ID and P6 using moment method based on the laboratory measurements of sensor spectral response, and (2) to quantify the influence of varying sensor spectral response on reflectance and Normalized Difference Vegetation Index (NDVI) measurements using surface reflectance spectra corresponding to different leaf area index conditions of crop target obtained through field experiment. Significant deviation of 4 to 14 nm in central wavelength and 1.6 to 14.07 nm in spectral width was observed for the corresponding channel of IRS sensors. Coefficient of variation of the order of 0.1 to 1.11% was noticed in E_o among various IRS sensors, which could induce a difference of 0.72 to 3.35% in the estimation of top of atmosphere reflectance for crop target. The variation in spectral response of IRS sensors implied a relative difference of the order of 0.91 to 3.38% in surface reflectance and NDVI measurements. Polynomial approximations are also provided for spectral correction that can be utilized for normalizing the artifacts introduced due to differences in spectral characteristics among IRS sensors.     

Reclamative grouping of ravines using Cartosat-1 PAN stereo data

Information on the depth and bed width of ravines (network of gullies) at large scales is critical for their reclamation and management. Hitherto such information has been generated from aerial photographs and space borne stereo images with medium to coarse ‘z’ – axis resolution. The present study, aims at demonstrating the potential of Cartosat ?1 (an Indian Earth observations satellite) stereo images with 2.5 m spatial resolution in deriving morphometric information on ravines for their reclamative grouping. The study area is a part of Jhansi and Hamirpur districts of Uttar Pradesh, northern India. The approach involves acquiring precise ground control points using Differential GPS (DGPS), triangulation, DEM extraction and generation of ortho image as well as anaglyphs for stereo viewing. The depth and bed width of ravines were measured in the field for validation. A comparison with field observations reveal that the bed width of ravines and depth can be measured successfully with Carto-1 stereo data. The anaglyph data was used to delineate various categories of ravines based on their depth and bed width. Results indicate that the Cartosat-1 stereo images are quite suitable for delineation of three categories of ravines, namely shallow (<3 m deep and <18 m bed width), medium deep (3–9 m deep and >18 m bed width) and deep (>9 m deep) which are important for their reclamation.     

Discrimination of newly planted and ratoon crops of sugar cane using multidate IRS-1C liss III data: A knowledge based approach

An advanced and accurate information of sugar cane production is an important component for the management of sugar cane industry. Remote Sensing is most viable technique which can provide the above information well in advance. Stratified sampling technique practiced in Crop Acreage and Production Estimation (CAPE) programme holds good for major crops with non-overlapping growth stages. Discrimination of ratoon and newly planted sugar cane crop is a challenging task. Single date remote sensing data does not suffice to discriminate the above two types of sugar cane. In the present paper, an attempt has been made to show how two date remote sensing data coupled with knowledge based approach dramatically improves the classification accuracy (98%) of sugar cane crop as compared to the stratified sampling approach (less than 90%). This has been demonstrated in a case study comprising parts of two districts of western Uttar Pradesh.     

利用ERS-1/2重轨干涉SAR数据提取DEM及其精度分析

介绍了重轨干涉SAR数据的图像配准、干涉图生成、基线估计及DEM生成的原理，利用1996年获取的西茂玛尼地区的ERS－1／2串行干涉SAR数据提取了DEM。并选控制点计算了所获得的DEM的误差。最后对影响DEM精度的各种因素进行了分析。     

ERS-2 SAR and IRS-1C LISS III data fusion: A PCA approach to improve remote sensing based geological interpretation

Fusion of optical and synthetic aperture radar data has been attempted in the present study for mapping of various lithologic units over a part of the Singhbhum Shear Zone (SSZ) and its surroundings. ERS-2 SAR data over the study area has been enhanced using Fast Fourier Transformation (FFT) based filtering approach, and also using Frost filtering technique. Both the enhanced SAR imagery have been then separately fused with histogram equalized IRS-1C LISS III image using Principal Component Analysis (PCA) technique. Later, Feature-oriented Principal Components Selection (FPCS) technique has been applied to generate False Color Composite (FCC) images, from which corresponding geological maps have been prepared. Finally, GIS techniques have been successfully used for change detection analysis in the lithological interpretation between the published geological map and the fusion based geological maps. In general, there is good agreement between these maps over a large portion of the study area. Based on the change detection studies, few areas could be identified which need attention for further detailed ground-based geological studies.     

DATA PROCESSING TECHNOLOGY OF AIRBORNE 3D IMAGE

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Irrigation command area inventory and assessment of water requirement using IRS-1B satellite data

Monitoring the crop acreage and irrigation water requirements vis-a-vis irrigation water supplies is important to obtain a realistic view of the “irrigation potential” and “potential utilised”. Satellite data provides information on crop area and thereby net irrigation water requirements of crops. A pilot study was taken up in Mahendragarh distributary canal in Haryana State to estimate net irrigation water requirement of crops under 17 minors for kharif and rabi seasons of 1992–93 period using IRS-1B satellite geocoded FCC images. These water requirements, when analysed with canal and tubewell water supplies for crops, show largescale deficiencies in the irrigation command area.     

基于三层C/S模式的测量在线数据处理服务

讨论了测量数据处理软件的在线实现问题;并基于三层C/S模式,探讨了从客户端、中间层到后端数据处理模块的实现方法;最后以三角网平差作为实例,详细说明了用.Java语言实现一个网上测量在线数据处理服务系统的全过程.     

Forest cover mapping of East district,Sikkim using IRS-1A LISS II satellite data

Remote sensing techniques have been applied to classify tour density classes within each of the forest type along with other major landuse/landcover classes in the East district, Sikkim using IRS-1A LISS II satellite data pertaining to the period of November, 1988. The shadow problem in rugged terrain and difficulty in acquiring cloud free data for different seasons pose problems to achieve considerable mapping accuracy. In the present study, the forests of the district were delineated through supervised classification techniques using maximum likelihood algorithm into five forest types as sal forests, subtropical broad-leaved forests, Himalayan wet temperate forests, Rhododendron forests and alpine forests. The alpine forests were further stratified into two categories as moist alpine scrub and dry alpine scrub. The statistical data obtained from the present study shows that 55.47 percent of the total geographical area of the East district was under forest cover. An overall accuracy of more than 85 percent in correctly delineating forest classes was achieved.     

A comparative evaluation of IRS-1A LISS-II and landsat MSS images using computer-aided lineament data analysis

Lineament patterns detected from remotely sensed data provide useful information to geoscientists, specially in the study of basement tectonics, groundwater targetting and mineral exploration. Improvements in the spatial resolution of satellite images have resulted in the detection of short and faint lineaments which have hitherto gone unnoticed The IRS-1A LISS-II data offers a significant improvement in spatial resolution as compared to the Landsat MSS. A set of computer programmes developed for analysis of lineaments were used to study the parameters such as lineament frequency, length and density in order to quantify the added information derived using IRS-1A LISS-II images. The incremental contribution of LISS-II images are of the order of 100 per cent for lineament frequency and about 60 per cent for total line kilometers of lineaments detected.     

Application of IRS-1A data for delineating buried channels in Southern part of Allahabad district of Uttar Pradesh

Two buried channels were identified in southern part of Allahabad district based on the visual interpretation of IRS-1 A LISS II FCC followed by detailed study of aerial photographs and cheks. It has been concluded on basis of the configuration of the channels that these were initially joined forming one channel which flowed from east to west although the present master slope of the area is from west to east. The present reversal of the drainage might have been caused by the neo-tectonic activity in the area. The buried channels provide potential ground water reservoirs in the area as proved by a few boreholes drilled on the channels. Some part of the area has become waterlogged due to the seepage of water from the canals cutting across one of the buried channels.     

基于B/S与C/S协同架构的航道整治三维辅助系统设计

根据航道整治过程中的实际需求,基于B/S与C/S协同架构,结合多波束水下CT实际扫测成果,设计了航道整治三维辅助决策支持系统。在网络环境下,实现了三维水下地形图及航道信息的实时更新、显示,并提供了一系列的3DGIS分析功能,为航道整治工作的辅助决策、指挥调度、安全生产预警等提供了有效支撑,实现了保障施工区安全、畅通的目的。