High Resolution TerraSAR-X Image Speckle Suppression and its Fusion with Multispectral IRS LISS –III Data for Himalayan Glacier Feature Extraction

In this study an attempt is made for studying the Himalayan glacier features using TerraSAR-X and Indian Remote Sensing Satellite, Linear Imaging Self Scanning System III (IRS LISS –III) images. New generation, synthetic aperture radar (SAR) data from TerraSAR-X (TS-X) sensor provide opportunity for glacier feature studies in Himalayan rugged terrain. Spot Light High resolution mode TS-X data give idea about glacial features which remained untraceable from other existing SAR system. However, presence of speckle noise in SAR images degrades the interpretability of the glacier features. Speckle suppression filters (Lee, Frost, Enhanced Lee, Gamma-Map) are applied on SAR intensity images. On the basis of field sight seeing and insitu observations it is observed that still features are not clear. Hence attempt has been made for fusing multitemporal multispatial speckle reduced TS-X SAR data and multispectral IRS LISS-III data for extracting the glacial features such as crevasses, exposed ice and superaglacier lakes. Principal component analysis (PCA) represents the high spectral resolution data in a linear subspace with minimum information loss. Herein, PCA based image fusion technique is adopted for this study and comparison is made between IHS fusion technique and PCA based technique for glacier studies in the Himalayan region.     

An Adaptive Noise Reduction Method for NDVI Time Series Data Based on S–G Filtering and Wavelet Analysis

In order to reduce the noise in advanced very high-resolution radiometer global inventory modeling and mapping studies normalized difference vegetation index (NDVI) version 3g time series data, we propose an adaptive noise reduction method based on the Savitzky–Golay filter and wavelet analysis and on curve-fitting and spectrum analysis. The noise reduction effect was analyzed and evaluated. Studies have shown that the denoising of data using asymmetric Gaussian and double logistic curve-fitting methods results in the loss of details of the NDVI changes and is not conducive to the extraction of vegetation phenotypic characteristics. The wavelet function, wavelet decomposition layer number, and the threshold determination method have a large influence on the noise reduction effect, and the adaptive method has high noise reduction efficiency and effectively reduces the noise in the NDVI data. The proposed method does not require the determination of the smoothing window size and threshold for each year, which represents an advantage for processing large amounts of data.     

Intergrated Airborne Gammaray Spectral and Satellite Data Analysis for U and REE Mineralisation — A Case Sudy from North Sagobandh Area, District Sonbhadra, Uttar Pradesh, India

Airborne gamma ray spectrometric (AGRS) and magnetic (AM) surveys were undertaken between 1986-1987 by Atomic Minerals Division, to locate uranium mineralisation along Son-Narmada rift zone. The imaging and interpretation of gridded AGRS data revealed many areas of anomalous radio elemental concentrations. These areas have been defined by taking thresholds as U ≥ 6 ppm, Th ≥ 24 ppm, K ≥ 2.3% and Total counts ≥ 5000 cps. The AGRS data integration with the satellite data viz., Landsat Multi spectral Scanner (MSS), Thematic Mapper (TM), and IRS LISS II data on different scales indicated the lithostructural controls of uranium mineralisation and also the predominance of the potash metasomatism in the vicinity of the southern Son rift and soda metasomatism further away in the south. p ]Systematic follow up ground checking of the target area located in the North Sagobandh area resulted in delineating the areas of K metasomatism, anatexis and grissenisation as the areas showing ≥ 2.3%K values. The depleted K, Th, and high U/Th values show zones of albitisation and oligoelasisation. The trends of radiometric breaks depicted by total counts distribution patterns defined the tectonostratigraphic boundaries. Besides these 26 radioactive anomalies with grades ranging from eU3O/0./012–0.18%, U3Ox B/r <0.01–0.3% and ThO2 0.00.5–0.1% having strike length 50–500 meters and outcrop thickness .5–2.5 meters. Ten locations of inland riverine sand placers of heavy minerals containing REE bearing minerals i.e. xenotime, monazite, rutile, ilmenite, zircon and traces of columbite-tantalite have been identified by using thorium and mixed source (U+Th) anomaly map. These sand placers have channel lengths of 100 - >500 meters and width of 1–2.5 meters, containing l.5%–9.04% heavy minerals.