False Colour Composite Research Articles

Study of Groundwater Prospects of the Crystalline Rocks in Purulia District, West Bengal, India Using Remote Sensing Data

Visual interpretation of satellite imageries of IRS P6 LISS III standard false colour composite (FCC) has been made for lineament and hydrogeomorphological analyses. Analyses of lineament density, lineament intersection density, spatial dis- tribution of hydrogeomorphic units and lithology have been carried out for the study of groundwater prospects in crystalline rocks. Each theme is assigned a weightage depending on its influence on the storage and movement of groundwater and each unit in every theme map is assigned a knowledge based ranking depending on its significance to groundwater occurrence. The cu- mulative scores have been worked out and the scored pattern has been contoured in preparing the final potential map using Surfer software and classified into five groundwater prospect categories which are further justified by hydrological studies.

A Simple Model of Mapping of Land Surface Temperature from Satellite Digital Images in Bangladesh

Land Surface Temperature is a key parameter in energy budget models, estimating soil moisture, forest detection and forecasting, monitoring the state of the crops and many other applications. In this work, a method has been developed to retrieve land surface temperature using the National Oceanic and Atmospheric Administration (NOAA) of USA, Advanced Very High Resolution Radiometer (AVHRR) satellite images. The land surface temperature has been determined taking AVHRR images from February to December in a year. Seasonal variations have also been studied. The results have been presented in the false color composition (fcc) map for each month. Studying the resulting maps it is found that there is a marked spatial and seasonal variations in the surface temperature among different regions of the country. We could not compare our result with the measured data as, till now, no measured data of surface temperature is available for our country. But it is observed that our result is well in conformity with the observed air temperature of the country. This method can thus be used for long term monitoring of surface parameters for the country. The long term study of surface temperature can be very much important for sustainable land resources development and to understand the effect of possible environmental changes.

Remote sensing techniques using Landsat ETM+ applied to the detection of iron ore deposits in Western Africa

Remote sensing methods enable the rapid and inexpensive mapping of surface geological and mineralogical features. This capability proves highly useful when working on isolated or inaccessible areas. In this study, several enhancements of Landsat Enhanced Thematic Mapper plus (i.e. band ratios, false colour composites and principal component analysis) were used and evaluated to obtain the best possible visualisation of iron deposits hosted in the Devonian sedimentary rocks of northwestern Africa. In particular, two test sites were chosen: southern Algeria (Djebilet area), where the literature mineralogical and geological data on iron mine fields were already available, and the Western Sahara (the southern flank of Tindouf Basin), which was investigated during a field campaign and was where the occurrence of an analogous sedimentary succession led us to hypothesise the possible presence of exploitable iron deposits. This work demonstrates the usefulness of multispectral imagery in the detection of iron-rich areas and establishes a full remote sensing procedure, which can be profitably applied to a wider region of Western Sahara and can provide interesting perspectives on the possibility of detecting new exploitable iron ore deposits in arid environments.

Classification of COSMO SkyMed SAR Data Based on Coherence and Backscattering Coefficient

A novel supervised classification approach is proposed for high-resolution dual-polarization (dual-pol) amplitude COSMO SkyMed images. Coherence, mean backscattering coefficient and backscatter difference images are generated, from which the False Color Composite (FCC) image is formed. A classification scheme based on maximum likelihood algorithm land cover classification is implemented on the false color composite image to classify the river, vegetation and the urban areas of Jharia, located in the state of Jharkhand in India using MATLAB 7.6 and ENVI 4.7.

Remote Sensing Extraction of Piedmont Potassic Alteration Zone in Hadamengou Gold Deposit District, Inner Mongolia Autonomous Region

Potsash feldspathization is one of the alterations which are closely related with gold mineralization in Hadamengou gold deposit, Inner Mongolia Autonomous Region. Piedmont potassic alteration zone is the product of potsash feldspathization, part of the zone is ore body. In the paper, we utilize Principal Component Analysis and Spectral Unmixing to extract the piedmont potassic alteration zone based on MAIS data. The result demonstrates that after Selective Principal Component Analysis, false color composite of the first, third and seventh principal components and false color composite of the results from Spectral Unmixing and arithmetic operator both achieve good results.

Nile River evolution in Upper Egypt during the Holocene: palaeoenvironmental implications for the Pharaonic sites of Karnak and Coptos

Here we present the results of a geoarchaeological study, undertaken in Upper Egypt, in the western part of the Karnak Temple and in Coptos. The geoarchaeological approach helps to better understand the fluvial dynamics of the Nile River in the close vicinity of these two Pharaonic sites, 35 km apart. Our investigation focused on i) a jetty discovered by the archaeologists of the Supreme Council of Antiquities (SCA) in front of the first pylon at Karnak and ii) the remains of Ancient Coptos, an important site from Predynastic to Roman times. We studied several stratigraphic profiles, manual boreholes (maximum depth of 5.5 m) and percussion drillings (maximum depth of 25 m). Sedimentological and magnetic susceptibility analyses help to characterise Nile River deposits and to identify the presence of aeolian deposits (associated with wadi fan deposits) in the lower part of the boreholes at both Karnak and Coptos. The data clearly indicate the continuous occupation of the Nile River around the sites during a part of the Dynastic period. Fluvial dynamics characterised by flood events, sandy accretions and thick Nile silty-clayed deposits are presented and discussed here for subsequent palaeoenvironmental reconstruction. Accurate levelling of the different profiles and boreholes, together with a topographic survey allow us to recover long sedimentological sequences and to correlate the different sedimentary units. Finally, in order to obtain a chronostratigraphic sequence, radiocarbon dates were obtained from wood, charcoal and ash samples (analyses undertaken at the laboratory of radiocarbon dating of IFAO, Cairo, Egypt). For Karnak, the presence of the Nile River in front of the first pylon in Karnak is attested from ca. 1450 BC until ca. AD 350 (from the beginning of the 18th dynasty until the end of Roman times), with a probable early flowing activity during the second part of the Middle Kingdom (1994-1650 BC) and the Second Intermediate Period (1650-1550 BC). The construction of a Geographic Information System (GIS) including the borehole results and the integration of Shuttle Radar Topography Mission data (SRTM), with the superimposition of False Colour Composition of a LANDSAT ETM+ image, helped to obtain a spatial interpretation of the results.

Integrating geologic and satellite imagery data for high-resolution mapping and gold exploration targets in the South Eastern Desert, Egypt

The granitoid-greenstone belts of the Arabian–Nubian Shield are well-endowed with lode gold and massive sulfide ores. Although generally characterized by excellent outcrops and arid desert realm, poor accessibility and lack of finance have been always retardant to detailed geologic mapping of vast areas of the shield. Lack of comprehensive geological information and maps at appropriate scales would definitely hinder serious exploration programs.In this study, band ratioing, principal component analysis (PCA), false-color composition (FCC), and frequency filtering (FFT-RWT) of ASTER and ETM+ data have substantially improved visual interpretation for detailed mapping of the Gebel Egat area in South Eastern Desert of Egypt. By compiling field, petrographic and spectral data, controls on gold mineralization have been assessed in terms of association of gold lodes with particular lithological units and structures. Contacts between foliated island arc metavolcanics and ophiolites or diorite are likely to be favorable loci for auriferous quartz veins, especially where the NW–SE foliation is deflected into steeply dipping NNW-trending shear planes. High-resolution mapping of the greenstone belt, structures and alteration zones associated with gold lodes in the study area suggests that dilatation by foliation deflection was related to emplacement of the Egat granitic intrusion, attendant with a sinistral transpression regime (i.e., ∼640–550Ma?). Gold mineralization associated with granitoid intrusions in transpression-induced pull-apart structures elsewhere in the Eastern Desert (e.g., Fawakhir, Sukari and Hangaliya mines) emphasize the reliability of this setting as a model for gold exploration targets in greenstone terrains of Egypt, and may be elsewhere in the Arabian–Nubian Shield.

False Color Composite System of Multi-Spectral RS Images Based on IDL

Several methods of the choice in assembled spectral and color composite in the false color composite of multi-spectral RS images are discussed. The research indicates that using the OIF method to carry on the band choice, unifying the easy and feasible RGB false colored synthesis and carrying on the method of image linear extension can realize the false color composite of multi-spectral RS images effectively, and the obtaining false color image has rich information and distinctive visual effects.

Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal

Abstract. Surface glacier debris samples and field spectra were collected from the ablation zones of Nepal Himalaya Ngozumpa and Khumbu glaciers in November and December 2009. Geochemical and mineral compositions of supraglacial debris were determined by X-ray diffraction and X-ray fluorescence spectroscopy. This composition data was used as ground truth in evaluating field spectra and satellite supraglacial debris composition and mapping methods. Satellite remote sensing methods for characterizing glacial surface debris include visible to thermal infrared hyper- and multispectral reflectance and emission signature identification, semi-quantitative mineral abundance indicies and spectral image composites. Satellite derived supraglacial debris mineral maps displayed the predominance of layered silicates, hydroxyl-bearing and calcite minerals on Khumbu Himalayan glaciers. Supraglacial mineral maps compared with satellite thermal data revealed correlations between glacier surface composition and glacier surface temperature. Glacier velocity displacement fields and shortwave, thermal infrared false color composites indicated the magnitude of mass flux at glacier confluences. The supraglacial debris mapping methods presented in this study can be used on a broader scale to improve, supplement and potentially reduce errors associated with glacier debris radiative property, composition, areal extent and mass flux quantifications.

Geology and Geomorphology of the Manipur Valley Using Digitally Enhanced Satellite Image and SRTM DEM in the Eastern Himalaya, India

Landsat ETM+ data and SRTM DEM data were used to delineate the geological, structural and geomorphological features in the intermontane Imphal Valley in Manipur, India. This area has simple geology, structural features and there- fore provides an ideal site to test the utility of remote sensing and GIS techniques in geological studies. The various techniques such as band ratioing, Principal Component Analysis (PCA) and generation of FCC (False Colour Composite) were employed on ETM+ data. The SRTM DEM data is used in generating the west-east transects of altitude pro- files in the valley for characterization of altitude levels of the litho-units. DEM derived drainage network and relative drainage density in the basin were used in interpreting the location of fault plane in the valley. The slope and lineament maps were prepared using SRTM DEM. It suggests that entire valley is covered by very low slope (0? - 9?). Lineaments are oriented N-S, 180? while in south-east of valley the direction is largely NW-SE. The change in lineament direction suggests that the eastern side of the valley is controlled by Indonesian Island arc strike direction.

Feature Extraction using Normalized Difference Vegetation Index (NDVI): A Case Study of Jabalpur City

This paper presents an improved method for the analysis of satellite image based on Normalized Difference Vegetation Index (NDVI). The method employs the multi-spectral remote sensing data technique to find spectral signature of different objects such as vegetation index, land cover classification, concrete structure, road structure, urban areas, rocky areas and remaining areas presented in the image. For land cover classification, some band combinations of the remote sensed data are exploited and the spatial distribution such as road, urban area, agriculture land and water resources are easily interpreteted by computing their normalized difference vegetation index. Different values of threshold of NDVI are used for generating the false colour composite of the classified objects. The simulation results show that the NDVI is highly useful in detecting the surface features of the visible area which are extremely beneficial for municipal planning and management. The vegetation analysis can be used for the situation of unfortunate natural disasters to provide humanitarian aid, damage assessment and furthermore to device new protection strategies.

Geomorphological Mapping Using Remote Sensing and GIS A Tool for Land Use Planning Around Shivpuri City, M.P., India

Landforms on the earth surface are expensive to map or monitor. Remote Sensing observations from space platforms provide a synoptic view of terrain on images. Satellite multispectral data have an advantage in that the image data in various bands can be subjected to digital enhancement techniques for highlighting contrasts in objects for improving image interpretability. Landforms are interpreted on the basis of interpretation element keys namely such as- tone, texture, size, shape, color etc. and extract the specific information from the false color composites LISS-III sensor images. Geomorphological units are classified on the basis differential erosion processes. In the study area, mainly presentational hills of Vindhyan sediments and pediments of granites are predominant landforms. Apart from these above geomorphic units, alluvial plain, pediplain, structural hills and residual hills are mapped using IRS-ID LISS-III satellite imagery using visual interpretation technique along with field check. Remote Sensing and GIS offers detecting, analyzing and time- cost effective way to fulfill these goals. Keywords- Geomorphology mapping, GIS, IRS-1D, LISS-III, Remote Sensing I. Introduction Now-a-days, Land use planning is important task for local and government authority to provide suitable land for human activities in the study area so it is realized that land use planning need to be developed in an integrated and comprehensive manner based on geomorphic study. In this study, Remote Sensing and GIS, tools and techniques are used to identify landform, geomorphic units and area mapping because geomorphology is the base of land use planning.

Groundwater exploration using remote sensing and geographic information systems in a semi-arid area (Southwest of Urmieh, Northwest of Iran)

Shortage of water required for drinking and agricultural uses is a subject with a vital importance in most arid and semi-arid regions. The area of this study is one of the semi-arid regions located in southwest of Urmieh lake, northwest of Iran, between N 37°00′, 37°15′ latitude and E 45°05′, 45°30′ longitude which is composed of Permian dolomitic limestone, limestone, and post-Jurassic granite with a very low primary porosity/permeability character. In order to delineate groundwater potential zones in this area, the study focused on identifying secondary porosity/permeability indicators such as lineaments, vegetation cover, lithology, drainage pattern, drainage density, etc. In this regard, a remote sensing and geographic information system-based methodology was selected. Landsat ETM, IRS (pan), SPOT data, digital elevation model, and digital image processing techniques such as filtering, false color composite, principal component analysis, band rationing and classification have been applied to reach the purposes. Information layers extracted for analysis and interpretation stage were then integrated with other data and modeled through the use of existing geographic information system (GIS) software and their related analytical functions. Finally, based on determined ground water favorability index for different sub zones, layers, weighting, and overlapping, a ground water potential index (GWPI) was defined which respectively was utilized to groundwater potential zoning and preparation of GWPI map of the region. Within the six different sub zones defined, two sub zones labeled with high and very good potential areas were highly recommended for further development and exploration purposes. Geophysical investigations in target areas confirm the labeled subzones. Based on the obtained results of the study, it can be concluded that remote sensing data are very useful tool to extract information of groundwater exploration. Also, application of geographic information systems to find target areas for groundwater exploration are effective to save time and cost.

A synergetic use of satellite imagery from SAR and optical sensors to improve coastal flood mapping in the Gulf of Mexico

AbstractThis work proposes a method for detecting inundation between semi‐diurnal low and high water conditions in the northern Gulf of Mexico using high‐resolution satellite imagery. Radarsat 1, Landsat imagery and aerial photography from the Apalachicola region in Florida were used to demonstrate and validate the algorithm. A change detection approach was implemented through the analysis of red, green and blue (RGB) false colour composites image to emphasise differences in high and low tide inundation patterns. To alleviate the effect of inherent speckle in the SAR images, we also applied ancillary optical data. The flood‐prone area for the site was delineated a priori through the determination of lower and higher water contour lines with Landsat images combined with a high‐resolution digital elevation model. This masking technique improved the performance of the proposed algorithm with respect to detection techniques using the entire Radarsat scene. The resulting inundation maps agreed well with historical aerial photography as the probability of detection reached 83%. The combination of SAR data and optical images, when coupled with a high‐resolution digital elevation model, was shown to be useful for inundation mapping and have a great potential for evaluating wetting/drying algorithms of inland and coastal hydrodynamic models. Copyright © 2011 John Wiley & Sons, Ltd.

Sensitivity of vegetation to decadal variations in temperature and rainfall over Northern Nigeria

The objective of this paper is to examine the extent vegetation has responded to decadal variations in temperature and rainfall over Northern Nigeria. The study covers four decades viz. the 1970s, 1980s, 1990s and the 2000s. Meteorological data from 11 stations covering 34 years (1971 to 2004) and satellite imageries of four dates, 1972, 1980, 1990 and 2000 taken during the wet season were analyzed in this work. Results obtained showed a compelling evidence that the vegetation of Northern Nigeria is sensitive to the decadal variations recorded in the region’s temperature and rainfall during the period studied. The results indicated that the average temperature has been rising by the decade with 0.31°C inthe 1980s and 0.09°C in the 1990s and 2000s while rainfall dropped in the 1980s by 103 mm, increased massively in the 1990s by 163 mm and decreased slightly by 2.42 mm in the 2000s. The highest maximum positive NDVI (normalized difference vegetation index) values of + 0.64 was recorded in 2000 while the lowest of + 0.21 occurred in 1990 and followed closely by + 0.27 of 1980.These results provide evidence as to the sensitivity of vegetation to decadal variations in temperature and rainfall over Northern Nigeria. Key words: Variations, FCC (false colour composite), NDVI (normalized difference vegetation index).

Lithology Discrimination in Foreland Basin with Landsat TM

The Kahramanmaras Foreland Basin (KFB) margins are formed by Paleozoic-Mesozoic limestone, metamorphic and ophiolite. This basin contains sandstone and claystone alternations with lesser amounts of reefal limestone, channelized conglomerates, debrites and slump deposits. An irregular topography and absence of path obscured the accurate and complete mapping of the basin. Thus, Landsat TM images were used. The RGB 751 false colour composites were chosen due to abundant claystone and limestone content of the KFB. The RGB PCA 145 was preferred due to high loading of TM bands 5 (clay and iron oxide mineral), 7 (carbonate mineral), 3 and 1 (albedo and topography). The RGB 5/7-5/1-4 (light green dots in 5/7 indicate enhanced claystone area and OH- bearing alteration zone; red dots in 5/1 indicate enhanced iron oxide bearing alteration zone; fourth band for water bearing minerals) shows the transportation way of sediments. The OH- and iron oxide bearing alteration zones are found on older source rocks and younger deposition area. Main lithological boundary, geometry and provenance properties of the KFB were satisfactorily obtained from the Landsat TM images. However, low spatial resolution (30 m) prevents detail facies discrimination that still requires hard field working and/or detailed satellite images.

Remote sensing interpretation of areas with hydrocarbon microseepage in northeast China using Landsat-7/ETM+ data processing techniques

Landsat-7 Enhanced Thematic Mapper Plus (ETM+) images were used to interpret hydrocarbon-induced alterations in the northwestern part of the Songliao Basin, northeast China. Spectral enhancements for locating hydrocarbon-related minerals on images included principal component analysis (PCA), band ratioing, optimum index factor (OIF) and false colour composite (FCC). Four principal component (PC) and four band ratio images showed outstanding spectral response of hydrocarbon-induced mineral and sediment assemblages: 1345-PC3 (third PC image on bands 1, 3, 4 and 5), 1357-PC3, 2357-PC3 and 3457-PC4, and band ratios 3/1, 4/3, 7/5 and 4/3–2/3. Five OIF-defined FCCs were informative and clear for anomaly interpretation. Consequently, heavy oil prospect areas totalling 159 km2 were delineated. Acidolysis hydrocarbon measurements of ground soil samples suggest high soil concentrations of light hydrocarbons, indicating that the tonal anomalies in the images have a geological origin. Thus, remote sensing interpretation can be a useful primary exploration tool in hydrocarbon-altered areas, provided that techniques are adapted to site characteristics.

Preparation of digital data sets on land use/land cover, soil and digital elevation model for temperature modelling using Remote Sensing and GIS techniques

Remote Sensing (RS) and Geographic Information Systems (GIS) are becoming powerful tools in climatological modelling. This study proposes an empirical methodology to prepare digital data set of land use/land cover, soil and digital elevation model (DEM) using RS and GIS techniques. The study area is Gangetic West Bengal and its neighborhood in the eastern India, where a number of weather systems occur throughout the year. Gangetic West Bengal is a region of strong heterogeneous surface with several weather disturbances. Standard false color composite (Std FCC) bands (green, red and near Infrared bands) of LANDSAT-7, ETM+ sensor are used to produce land use/land cover dataset. DEM is built using the contours and spot heights which are collected from Topographical maps of the region. With the help of soil region map of West Bengal and soil region map of India the soil texture dataset is built. All the data sets are converted to the spatial resolution of 1km and 5km, which can be used as the independent variables for climatological modelling (specifically air temperature modelling) of the study area.

Application of Remote Sensing in Monitoring of Faults

The Siyah Bisheh area is located in central part of Alborz zone, 40km south of Amol, Iran. Rock units exposing in the area consists of sedimentary (carbonates, sandstone, siltstone), volcano- sedimentary (andesite to andesitic tuff, tuff), ignimbrite and basalt. when erosion and tectonics have rendered volcanic structures undetectable, remote sensing provides an invaluable tool for their identification, with finding relation between lithology and vegetation is showed that the integrated use of remote sensing techniques and field studies as a powerful tool to distinguish and map the relationships between rock units, structures and alteration zones associated with mineral deposits along the siyah Bishe area. The main image analysis techniques involved in this study were principal component analysis (PCA) and false color composite (FCC). In this study, an anomaly area is distinguished in the southeastern part of the Siyah Bishe area. Hydrothermally altered rocks contain economic mineral deposits whereas unaltered country rocks are non-mineralized. Approximately 5 km2 of the area is underlain by altered rocks, but less than 1 km2 of the altered area contains economic minerals.

Atmospheric correction to IRS-P6 AWiFS data and its validation with ground measurements: A study over the semi-arid region

In this study, we have implemented a fast atmospheric correction algorithm to IRS-P6 advanced wide field sensor (AWiFS) satellite data for retrieving surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code. The algorithm requires information on aerosol optical depth (AOD) for correcting the satellite dataset. The atmospheric correction algorithm has been tested for IRS-P6 AWiFS False colour composites covering the International Crops Research Institute for the Semi-Arid Tropics Farm, Patancheru, Hyderabad, India, under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e. red soil, chick pea, groundnut and pigeon pea crops were conducted to validate the algorithm. Terra MODIS AOD550 validated with Microtops-II sun photometer–derived AOD500 over the urban region of Hyderabad exhibited very good correlation of ∼0.92, suggesting possible use of satellite-derived AOD for atmospheric correction.