K. Vinod Kumar

Effect of Sun Elevation Angle on DSMs Derived from Cartosat-1 Data

Along-track stereoscopic satellite data are increasingly used for automatic extraction of digital surface models (DSM) due to the reduced radiometric variation between the images. Problems remain with the quality of such DSMs, especially in steep terrain. This paper explores the accuracy of DSMs extracted from Cartosat-1 data acquired under high and low sun elevation angle conditions in High Himalayan terrain. The metric accuracy of the DSM was estimated by comparing it with check points obtained with a differential GPS . Additionally, we used spatial discrepancy of drainage lines to estimate errors in the DSM due to spatial auto- correlation. For valleys perpendicular to the satellite track, the DSM extracted from a low sun elevation angle data showed 45 percent higher spatial accuracy than the DSM extracted from high sun elevation angle data. The results indicate that the sun elevation angle and valley orientation affect the spatial accuracy of the DSM, though metric accuracy remains comparable.

Integrated approach of using ASTER-derived emissivity and pixel temperature for delineating different granitoids – a case study in parts of Dharwar Craton, India

Abstract We have delineated different granitoids based on variation in emissivity and relative surface temperature recorded in thermal bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor of EO-1 satellite. In this regard, we have used emissivity normalization algorithm to derive broadband emissivity from thermal bands of ASTER sensor to delineate different lithounits of the granitoid family. We have compared emissivity and radiance image composites in terms of delineation of different granitoids. We have also used false colour composite (FCC) image derived using two emissivity bands and temperature (derived using emissivity normalisation method) bands to delineate different granitoids. We could differentiate different granitoids in the three-dimensional (3D) data space of ASTER-derived emissivity bands (second and third bands) and temperature bands. Based on the analysis of 3D scatter plot, we also proposed a ternary diagram of emissivity and temperature, which can be used to delineate different granitoids.

A Tool Assessing Optimal Multi-Scale Image Segmentation

Image segmentation to create representative objects by region growing image segmentation techniques such as multi resolution segmentation (MRS) is mostly done through interactive selection of scale parameters and is still a subject of great research interest in object-based image analysis. In this study, we developed an optimum scale parameter selector (OSPS) tool for objective determination of multiple optimal scales in an image by MRS using eCognition software. The ready to use OSPS tool consists of three modules and determines optimum scales in an image by combining intrasegment variance and intersegment spatial autocorrelation. The tool was tested using WorldView-2 and Resourcesat-2 LISS-IV Mx images having different spectral and spatial resolutions in two areas to find optimal objects for ground features such as water bodies, trees, buildings, road, agricultural fields and landslides. Quality of the objects created for these features using scale parameters obtained from the OSPS tool was evaluated quantitatively using segmentation goodness metrics. Results show that OSPS tool is able determine optimum scale parameters for creation of representative objects from high resolution satellite images by MRS method.

Geological and Geomorphological Studies of a Part of Ganjam District, Orissa by Remote Sensing Techniques

Geological and geomorphological mapping was carried out for a part of Ganjam district, Orissa through visual interpretation of IRS-IB LISS II flase colour composites. Various lithounits such as khondalites, charnockites and granites of Archaean age were mapped. The study area is traversed by two sets of vertical joints — one trending in NE-SW direction and the other in NW-SE direction. Three sets of lineaments in the study area trending in NE-SW, NW-SE and ENE-WSW suggest that the study area was subject to very high degree of deformation in the past. Major geomorphic units delineated are, Hills, Pediments, Valley Fills, New Flood Plains, Old Flood Plains, New Coastal Plains and Old Coastal Plains. Different landforms under each geomorphic unit are also mapped.

Inventory of Glacial Lakes and its Evolution in Uttarakhand Himalaya Using Time Series Satellite Data

Glacier recession and the expansion of glacial lakes in the recent decade is an observable fact in the Himalayan Cryosphere. The present study used the potential of Indian Remote Sensing (IRS) high resolution LISS IV multispectral data to generate the latest inventory of glacial lakes in Uttarakhand Himalaya. A combination of five different types and a total of the 362 glacial lakes were identified in Uttarakhand Himalaya. The historical Corona and Hexagon data were analysed for the growth of selected glacial lakes. Pro-glacial/moraine-dammed lakes are growing consequent to the recession of the glaciers. The inventory shows eight glacial lakes are critical considering the outburst potential. This shows the glacial lakes are dynamics in nature and vary, dimension and type in time and space.

Satellite based mapping and morphogenetic analysis of the landforms in the tertiary fold belts of parts of Tripura, India

In the present study, satellite-based mapping and morphogenetic analysis of eastern part of Tripura has been attempted. Landforms are delineated based on conjugate analysis of satellite-imaged and satellite-derived digital elevation data. Further, landforms were classified based on hierarchical three-tier classification system where genesis is used as a criteria to classify the landforms in the first level followed by nature of their dissection and the geometric forms of the landform in second and third level, respectively. During the analysis, it has been observed that most of the landforms are structural in origin and their orientations are guided by the geological lineaments although the variations in the dissection pattern of the landforms are related to the changes in the underlying lithology. The implementation of quantitative analysis using hypsometric integral and ruggedness index of geomorphic parameters indicates that the landforms are immature but have been evolving towards maturity.

Comparative analysis on utilisation of linear spectral unmixing and band ratio methods for processing ASTER data to delineate bauxite over a part of Chotonagpur plateau, Jharkhand, India

We have attempted comparative analysis of the utility of linear spectral unmixing (LSU) method and band ratios for delineating bauxite from laterite within the lateritic bauxite provinces of Chotonagpur Plateau, Jharkhand of India. This was attempted based on processing of visible–near infrared (VNIR) and shortwave infrared (SWIR) spectral bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor. In LSU method, spectral features of main constituent minerals of lateritic bauxite are used to decompose the pixel spectra to estimate the relative abundance of bauxite and laterite in each pixel to spatially delineate bauxite within laterite. We have also compared the bauxite map derived using LSU method with bauxite maps of two band ratios in terms of spatial disposition of bauxite. We also have attempted to relate the abundance values of pixels of LSU-based bauxite map with band ratio values of bauxite pixels of two selected bauxite indices.

Remote Sensing based assessment of glacial lake growth on Milam glacier, Goriganga basin, Kumaon Himalaya

The climate change of the twentieth century had an evident effect on glacier environments of the Himalaya. Temporal images of Indian Remote Sensing satellites provide an opportunity to monitor the recession of glacier and development of glacial lakes in the Himalayan cryosphere with a cost to time benefit ratio. The recession of Milam glacier and subsequent growth of a proglacial lake near the snout was analysed using Resourcesat-1 and Resourcesat-2 data. The recession of 480 m during 2004 to 2011 and growth of 47 epiglacial ponds over Milam glacier shows the glacier is in a state of imbalance and losing the ice by downwasting.

Discrimination of low-grade magnetite ores using remote sensing techniques

The remote sensing community in geology is widely using the Multispectral Landsat Thematic Mapper (TM) data which has a wider choice of spectral bands (six between 0.45 and 2.35 μm, plus a thermal infrared channel 10.4-12.5 urn). These were evaluated for low-grade magnetite ores mapping over the high-grade granulite region of Kanjamalai area of Tamil Nadu state, India. The Fourier Transform Infrared (FTIR) spectroscopy data (0.4-4.0 μm) for powders of the magnetite ores exposed with granulite rock and published spectral reflectance data were used as guides in selecting TM band reflectance ratios, which maximize discrimination of magnetite ores on the basis of their respective mineralogies. The study shows that the weathering mineralogy of magnetite ores causes absorption features in their reflectance spectra which are particularly characteristic of the near infrared. Comparison of TM data with field and petrographic observations shows the presence of magnetite and aluminosilicate minerals & show strong absorption at 0.7-1 μ.m wavelength spectral region & increase in the product of two TM band ratios: band 5 (1.55-1.75 μm) to band 4 (0.76-0.9 μm) and band 3 (0.63-0.69 μm) to band 4 (0.76-0.9 μm). Various computer image enhancement and data extraction techniques such as interactive digital image classification techniques using color compositing stretched ratio, maximum likelihood and thresholding statistical approaches using Landsat TM data are used to map the low-grade magnetite ores of the granulite region. The field traverses and local verification enhanced to map the other rock types namely granulites and gneisses of the study area.

Structural Control on Occurrence and Dynamics of Coalmine Fires in Jharia Coalfield: A Remote Sensing Based Analysis

In the present study, attempt has been made to understand the structural controls on preservation and dynamics of coal fires by establishing spatial relations of these fires with the faults, in the Jharia coal field. This is carried out, using recent distribution of the coal fires mapped from Landsat 8 TIRS data and historical coal fire distribution data derived from earlier studies (2003, 2006 and 2012). The major mapped fires are restricted to five different locales in the coalfield, namely Kujama, Kusunda, Katras-Mudidih, Shatabdi and Nadhkarkee-Jayramdih. Spatial analysis of different coal fire locales with respect to the geological map indicates that the fires may be associated with faults. Areal extension of fires coincide with the trend of faults (NW-SE around Kusunda and E-W around Katras). Further, the temporal preservation of the fires are also controlled by these faults. Fires associated with faults sustain for longer time than the fires that are not in proximity to the faults. This indicates that, these faults may have acted as conduits in supplying oxygen for preserving the coal fires over a period of time. Further, these faults permit the propagation and spread of the fire, through the arealy exposed fractures developed along their trends.