The evaluation of digitally enhanced Indian Remote Sensing Satellite (IRS) data for lithological and structural mapping

The potential of digitally enhanced Indian Remote Sensing Satellite (IRS) data for preparation of lithological and structural maps is explored in two test sites representing different geological settings in parts of Karnataka. Test site 1 is an area around Mattod, which mainly consists of Chitradurga rocks and peninsular gneiss, and the terrain is characterized by bare soil and is devoid of thick vegetation. Test site 2 is an area around the Bababudan belt, which mainly comprised of Bababudan and Chitradurga rocks and peninsular gneiss, and the major part of the area is covered under thick vegetation. Different digital enhancement techniques have been performed, and the expression of different lithological and structural features in the digitally enhanced products were qualitatively assessed. Based on this assessment, only those products which offered additional information than the standard false colour component (FCC) were selected and utilized along with standard FCC in the preparation of geological and structural maps. Attempts have been made to understand the advantages and limitations of using optical remote sensing data for deriving lithological and structural details. The maps created through using digitally enhanced IRS data have helped to revise/modify the existing geological map prepared through conventional method of mapping to considerable extent in terms of refined lithological boundaries, delineation of unmapped rock units, mapping of lineaments, and their networks. The results of the study has clearly brought out the fact that the geological map prepared from the optical remote sensing data at a shorter time interval is broadly comparable to that of the geological map prepared through conventional techniques over several years. Also the study has highlighted that the broad-band spectral resolution optical remote sensing data can be effectively utilized for lithological and structural demarcation, only when the terrain is: (i) exposed with rock outcrops and their weathered derivatives; (ii) characterized by rock units which greatly differ in terms of physico-chemical properties; and (iii) devoid of vegetation cover.     

Determination of palaeotectonic and neotectonic features around the Menderes Massif and the Gediz Graben (western Turkey) using Landsat TM image

Western Turkey contains both spectacular palaeotectonic and neotectonic features of the Anatolian block. The first of these features is the Menderes Massif, a huge metamorphic terrain comprising various lithologies; the second is the Gediz Graben, one of the most well‐known extensional features that formed during the neotectonic period of Turkey's complex geological history. In the study area, approximately E–W‐trending Neogene grabens, such as the Gediz, obliquely subdivide palaeotectonic massifs (such as the NE–SW‐oriented Menderes Massif) and mélange rocks. The terms Menderes Massif and Gediz Graben indicate different products of different tectonic regimes.

In this study, lithological components of the region were determined using a Landsat Thematic Mapper (TM) image. Band‐ratioing and principal component analysis (PCA) were chosen for lithological discrimination of the outcropping geological units. After processing, PCA gave the best results in terms of lithological differentiation. Furthermore, certain band‐ratio colour composites (5/7, 5/4, 4/1) are sensitive to lithological differences in RGB (red, green and blue) space and thus provide a general understanding of the distribution of rock‐forming minerals, such as known hydroxyl‐bearing and ferric iron minerals, as well as the vegetative characteristics of the region. However, a structural‐analysis study, including visual inspection and edge‐enhancement techniques, played a complementary role in the geological analysis of the region. Outcrops of the Menderes Massif metamorphic rocks, mélange rocks and Neogene cover associated with the Gediz Graben are favourable for remote sensing studies in so far as they allow ease of interpretation and geological evaluation by researchers. One of the most notable results derived from this study was the discrimination of younger neotectonic, fluviatile occurrences from the palaeotectonic Menderes Massif metamorphic rocks and Izmir–Ankara Suture Zone mélange rocks. Additionally, boundaries of the active Gediz Graben have been delineated.     

甘肃北山白峡尼山地区多源遥感岩性制图研究

甘肃北山地区地质构造复杂,岩浆活动强烈,该区工作程度较低,已有1：20万、1：5万地质图对区内岩性（如中酸性侵入岩）圈定较为笼统,且界线不够准确。以甘肃北山白峡尼山地区为研究区,利用彩色空间变换（IHS）、Brovey等方法对ETM多光谱图像与资源三号（ZY3）全色波段高分辨率图像进行空间分辨率融合,获得兼具ETM光谱分辨率与资源三号空间分辨率之长的高分辨率图像。再对原始影像进行比值、主成分分析及假彩色合成等增强处理,突出其岩性差异,将各种方法处理的影像与数字高程模型（DEM）数据结合构建三维影像,进行综合解译。对解译结果进行野外验证、样品薄片鉴定及反射光谱特征分析,据此对结果进行修正,获得了研究区遥感解译地质图。结果表明：对于西部基岩露头较好地区,利用多源遥感数据融合可更新现有地质图,为后续填图、找矿工作提供参考。     

Lithological mapping of the Troodos ophiolite, Cyprus, using airborne LiDAR topographic data

Traditional field-based lithological mapping can be a time-consuming, costly and challenging endeavour when large areas need to be investigated, where terrain is remote and difficult to access and where the geology is highly variable over short distances. Consequently, rock units are often mapped at coarse-scales, resulting in lithological maps that have generalised contacts which in many cases are inaccurately located. Remote sensing data, such as aerial photographs and satellite imagery are commonly incorporated into geological mapping programmes to obtain geological information that is best revealed by overhead perspectives. However, spatial and spectral limitations of the imagery and dense vegetation cover can limit the utility of traditional remote sensing products. The advent of Airborne Light Detection And Ranging (LiDAR) as a remote sensing tool offers the potential to provide a novel solution to these problems because accurate and high-resolution topographic data can be acquired in either forested or non-forested terrain, allowing discrimination of individual rock types that typically have distinct topographic characteristics. This study assesses the efficacy of airborne LiDAR as a tool for detailed lithological mapping in the upper section of the Troodos ophiolite, Cyprus. Morphometric variables (including slope, curvature and surface roughness) were derived from a 4 m digital terrain model in order to quantify the topographic characteristics of four principal lithologies found in the area. An artificial neural network (the Kohonen Self-Organizing Map) was then employed to classify the lithological units based upon these variables. The algorithm presented here was used to generate a detailed lithological map which defines lithological contacts much more accurately than the best existing geological map. In addition, a separate map of classification uncertainty highlights potential follow-up targets for ground-based verification. The results of this study demonstrate the significant potential of airborne LiDAR for lithological discrimination and rapid generation of detailed lithological maps, as a contribution to conventional geological mapping programmes.     

甘肃北山辉铜山地区镁铁岩体遥感识别方法研究

ASTER(先进星载热发射和反射辐射仪)已被广泛应用于岩性识别研究中,但在国内综合采用多种方法增强并识别镁铁-超镁铁岩体信息的研究较少。以甘肃北山辉铜山地区为研究区,综合应用比值法、最小噪声分离和镁铁岩指数等方法处理研究区ASTER数据,以突出辉铜山地区镁铁-超镁铁岩信息。将处理结果与地质图对比、综合分析,圈定了11处疑似辉长岩体,对其中9处进行野外验证,全部与遥感分析结果吻合,证明了结果的有效性。该方法可以应用于西部地区镁铁-超镁铁岩体识别工作中。     

光谱遥感岩矿识别基础与技术研究进展

遥感技术的发展与地物光谱特征的研究密不可分。主要从光谱遥感发展与地质应用的趋势出发,从光谱遥感岩矿识别基础与识别技术方法两方面阐述了光谱遥感的研究进展。对于遥感岩矿的识别基础,主要阐述物谱关联和物理模型研究的技术方法与进展以及其对遥感地质应用的促进与深化。在技术方法方面,主要从多光谱与成像光谱两个层次上,分析利用光谱特征进行岩石矿物识别的研究进展及其潜力与可行性。强调了岩石矿物光谱特征在遥感岩矿识别与地质成因信息提取中的重要性。     

The present state of the remote sensing applications to geological sciences in Greece

This paper describes the Greek University Departments and Government Institutes involved in the remote sensing application to geological sciences. Consequently, it reviews the geological-remote sensing investigations that have been carried out by the researchers of the above Departments/Institutes during the last 10 years

The majority of the Greek geological remote sensing researches have taken place in two remote sensing units, installed in the Institute of Geology and Mineral Exploration (IGME) at Athens and in the Geology and Physical Geography Department, at Aristotle University, Thessaloniki

In the IGME, the research was orientated to map and study lineaments related to faults, geological structure and/or hydrogeology, mineralization, in various areas in Greece, by the use of visual image analysis of LANDSAT (MSS, TM) data and partly by the use of SIR-A data

In the Department of Geology-Physical Geography, the research was firstly orientated to land systems mapping (land classification and land evaluation), delineation of drainage systems, in various Greek territories, by the use of visual image analysis of LANDSAT (MSS, RBV, TM) and SPOT (PA) stereopairs. Recently, the research has been orientated to geomorphological and tectonic (lineaments) mapping because the major structural and geomorphological elements are well displayed on certain digitally enhanced LANDSAT/TM and SPOT/XS, imageries, and partly on SIR-A imageries

The above reconnaissance maps are of considerable interest because they provide the framework for future construction of the same scale (1:250000-1:125 000) various detailed thematic maps (especially in identified critical areas) by geologists, hydrologists, soil scientists, mineralogists, geophycists, seismologists and other geo-scientists.     

Spectral characterization of ophiolite lithologies in the Troodos Ophiolite complex of Cyprus and its potential in prospecting for massive sulphide deposits

The island of Cyprus hosts one of the best preserved ophiolite sequences of the world: the Troodos massif. Lithologically the complex comprises a mantle series of ultramafic rocks overlain by gabbros and (plagio)granites. The crustal sequence consists of dyke swarms with two series of pillow lavas at the top known as the lower pillow lava and the upper pillow lava. Massive sulphide deposits, that have for long been exploited in Cyprus, occur at the contact between the lower and upper pillow lava series. This contact is difficult to map in the field. In this paper we explore the possibility of using advanced image processing techniques to discriminate the main lithological units to guide in mineral prospecting. A detailed field-spectral stratigraphic study forms the basis for the selection of potential spectral end-members characterizing the TM image used. It is shown that spectral angle mapping of TM data can provide mineralogical maps that compare favourably with known surface geology and provide insight in potential prosperous areas for mineral exploration when combined with standard hydroxyl and iron oxide mapping ratio images. Our work demonstrates how remote sensing can be used for mineral exploration at a reconnaissance stage in ultramafic terrains.     

Geological mapping and detection of oblique extensional structures in the Kenyan Rift Valley with a SPOT/Landsat-TM datamerge

Panchromatic SPOT and Land sat Thematic Mapper (TM) data were merged using an IHS approach to receive a satellite composite as a basis for detailed geological mapping in the Gregory Rift of East Africa. The advantages of the new image product compared to SPOT-XS and ‘pure’ Landsat-TM images and the correlation between the spectral signatures received from the TM data and the mapped geological units are discussed. The Pleistocene to Holocene lava flows, tuffs and sediments of the Rift floor could be divided into several lithological units due to their different spectral characteristics and surface textures. Thus, by the help of the satellite image interpretation, in comparison to the official geological map of this area, the amount of lithological units could be doubled and 80 percent of the minor faults were mapped for the first time.

Several N-S striking horst and graben structures were delineated, which are confined by conjugate dextral oblique-slip faults. This attests a NW-SE extensional movement of the compartments subparallel to the trend of this part of the Gregory Rift. The Rift Segment may then be interpreted in terms of a transform or transfer (accommodation) fault zone.     

Evaluation of cross-track illumination in EO-1 Hyperion imagery for lithological mapping

Hyperspectral remote sensing data is a powerful tool for discriminating lithological units and for the preparation of mineral maps for alteration studies. The spaceborne hyperspectral Hyperion sensor, despite its narrow swath width (～7.5 km), possesses great potential with its 196 channels within the wavelength range 426.82–2395.50 nm. Although it has many advantages such as low cost and on-demand coverage, much uncertainty exists in the utility of its applications. For example, poor signal-to-noise ratio, the presence of sensor-specific defects and thicker atmospheric column due to its spaceborne platform makes certain environmental and geological applications difficult or impossible. In this article we demonstrate these calibration-related uncertainties, which are manifest from the preprocessing stage to the classification stage. In addition, the intimate mixing of minerals within specific targets, for example within individual outcropping lithological units or endmembers, adds uncertainty to our spectral discrimination results. The aim of this study was to develop and evaluate an approach for geological mapping of outcrops with Earth Observing-1 (EO-1) Hyperion data. Atmospheric corrections and correction for cross-track illumination (CTI) variations (smile) were determined at different wavelength regions: the visible–near-infrared (VNIR; 420–1000 nm) and shortwave infrared (SWIR; 1000–2400 nm) regions. Our methodology was tested in a selected site at Central Anatolia, Turkey containing minimal vegetation cover. The results obtained from the image analyses were then compared and assessed with field observations and spectral measurements.     

Application of Landsat Thematic Mapper data in sabkha studies at the Red Sea coast

Salt-enriched flat areas are known as sabkhas in the Red Sea coasts. Previously classified sabkhas north of Jeddah city, Saudi Arabia were examined by remote sensing techniques. Confirmation of ground studies was reached with the synoptic coverage and spectral characteristics of the Landsat digital data. New maps were produced utilizing satellite data; this may include geomorphological and sabkha zonation maps. False colour, ratio and principal components composites were used in this study by image analysis system. Three main parameters, i.e., moisture content and its salinity, salt content and water-table level are exhibiting themselves as different colours in the coloured images. The approach described herein is recommended to be applied along the Red Sea coasts and other similar areas in order to present a preliminary but precisely identification of sabkha environments utilizing remote sensing techniques.     

TM与ETM影像融合用于地质构造解译

多源遥感影像数据融合是一种通过高级影像处理技术来复合多源遥感影像的技术，其目的是将单一传感器的多波段信息和不同传感器提供的信息加以综合，以提高获取信息的有效性和准确性，解译的可靠性，以及形成对目标的完整一致的描述。本采用TM与ETM经图像处理和融合，用于对地质构造解译，取得良好效果。     

典型地震次生地质灾害多光谱遥感影像特征图谱研究

为从地质灾害多光谱遥感影像资源中挖掘有用的信息,形成标准化、定量化的地质灾害遥感判读知识,进行地震次生地质灾害遥感影像特征图谱研究。以"5·12"汶川地震重灾区地震次生地质灾害滑坡、碎屑流和崩塌为例,首先提取灾害体单元的遥感影像,选取其光谱、纹理和色彩方面的20种遥感影像特征参数并统计参数值;然后对特征参数进行归一化处理,并通过主成分分析得到利用第一、第二、第三主成分表达的各类地震次生地质灾害的影像特征图谱。经过测试样本验证,上述几类图谱可表征相应地震次生地质灾害类型的影像特征。揭示了不同类型地震次生地质灾害遥感影像特征之间的关系,并为遥感影像中灾害体的识别提供了定量化和可视化的知识。     

遥感影像的高性能并行处理技术研究

随着空间遥感技术和对地观测技术的不断发展,光学、热红外和微波等不同技术手段可以获取同一地区的多种遥感影像数据（多时相、多光谱、多传感器、多平台和多分辨率等）,每天获取的遥感数据量越来越大。同时,大量的遥感应用需要快速地对这些遥感数据进行处理与分析,提供辅助决策信息。因此,如果不能及时进行数据处理,这些数据就会失去时效性,甚至失去数据本身的价值。高性能计算与并行处理技术,加速了遥感影像数据处理与信息提取的进度,如大规模多处理系统、网格与云计算技术、通用图形处理器（GPGPU）等。文中综述了高性能计算、并行处理及云计算技术应用于遥感领域的最新进展,给出了一些研究与应用范例,并提出了当前高性能遥感影像处理所面临的一些挑战。     

Using the mixture-tuned matched filtering method for lithological mapping with Landsat TM5 images

Hyperspectral images are widely employed for geological mapping because of their high spectral resolution. In this article, we develop the mixture-tuned matched filtering (MTMF) method, which can provide highly accurate mapping using the minimum ground-based data. This method is applied in the Malayer region of western Iran, which is composed of various lithological units. MTMF and minimum noise fraction (MNF) methods were applied to a Thematic Mapper 5 (TM5) image, and minimum number of training data based on field observation were used to produce a suitable false-colour image in which locations of lithological units were given. Finally, classification of six desired lithological units was done by the maximum likelihood classification (MLC) method. Results of lithological mapping show that although minimum ground-based data were used, the accuracy of classification is 82.3%. In addition, evaluation of the above-mentioned false-colour image reveals that the algorithm presented enhances the separability of units in the image by 7.3%, which can partially compensate for the low spectral resolution of the image used.     

Mapping the Buraburi granite in the Himalaya of Western Nepal: Remote sensing analysis in a collisional belt with vegetation cover and extreme variation of topography

The aim of the present study is to define the most suitable methodologies for ASTER data pre-processing and analysis in order to enhance peraluminous granitoid rocks in rugged and vegetated areas.The research started with raw image data pre-processing and continued with a comparison of satellite, field and laboratory data. The masking technique adopted to isolate rocky pixels was of fundamental importance to perform further analysis. An integration of density-sliced images and false colour composite images of Band Ratio, Relative Absorption Band Depth and Principal Component Analysis allowed us to generate a geological map that highlights a new granitoid body (Buraburi Granite) and the surrounding host rocks in the Dolpo region (western Nepal). The Buraburi Granite was mapped and sampled integrating remotely sensed ASTER data with analysis of rocks and minerals spectral signatures.The innovative approach that we have adopted considers the absorption features of particular lichen species (acidophilic). The results highlight the importance of considering acidophilic lichen means of detecting granitoid rocks. Furthermore, since peraluminous granitoids (i.e. Buraburi granite) have a considerable Al2O3 bulk rock content, the Muscovite Al-OH absorption peaks centred in the 6th ASTER band were also considered an important parameter for their detection.Field observations confirm the results of remote sensing analysis showing the intrusive relationship between the newly discovered 110 km² granitoid body and the wall rocks of the Higher Himalayan Crystalline and the Tibetan Sedimentary Sequence.In conclusion, the proposed methods have great potential for granitoid mapping in vegetated and rough terrains, particularly those with climatic and geological conditions similar to the ones of the Southern Himalayan belt.     

An efficient texture image segmentation algorithm based on the GMRF model for classification of remotely sensed imagery

Texture analysis of remote sensing images based on classification of area units represented in image segments is usually more accurate than operating on an individual pixel basis. In this paper we suggest a two-step procedure to segment texture patterns in remotely sensed data. An image is first classified based on texture analysis using a multi-parameter and multi-scale technique. The intermediate results are then treated as initial segments for subsequent segmentation based on the Gaussian Markov random field (GMRF) model. The segmentation procedure seeks to merge pairs of segments with the minimum variance difference. Experiments using real data prove that the two-step procedure improves both computational efficiency and accuracy of texture classification.     

矿物与岩石的可见-近红外光谱特性综述

矿物和岩石的系统光谱学研究是当今高光谱遥感发展的基础。在简要介绍了吸收光谱产生的电子过程和振动过程机理后,系统归纳了主要矿物类型和岩石类型的可见-近红外光谱特征。认为矿物的吸收光谱主要由二价、三价铁离子和过渡族元素的电子跃迁以及晶体场效应等电子过程产生;此外,还可以由水分子、Al-OH、Mg-OH、碳酸根的振动过程及卤化物的色心和硫化物的导带产生;岩石的吸收光谱都是杂质、包体、蚀变及替代成分产生的,主要为铁、水和羟基、碳酸根、硼酸根的光谱。最后指出,不同物理、化学环境下的矿物光谱特征变异研究在将来的高光谱遥感地质勘察中将变的更为重要。     

国产遥感影像分类技术应用研究进展综述

遥感影像分类技术为我国遥感影像应用于生态建设、绿色发展、乡村振兴、脱贫攻坚和"一带一路"构建等提供了重要的技术支撑,在服务经济社会发展、建设美丽中国、保障民生安全等方面具有重要意义.近年来,大数据、人工智能技术的飞速发展,使得国产遥感影像在分类应用的研究取得重大发展.简要分析了遥感影像分类技术及每阶段存在的问题;对国内...