<Emphasis Type="Italic">Integrated Remote Sensing and</Emphasis> Structural Analysis Studies of Tayyib Al-Ism Area,Northwestern Arabian Shield,Saudi Arabia

Geological and structural mappings of Tayyib Al-Ism area were carried out using the rocks finite strain data, the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data and the field based observations. To analyze the finite strain in the studied rocks, the R_f /? and Fry methods are applied to feldspar porphyroclasts and mafic grains from nine metavolcano-sedimentary samples (Hegaf Formation), four diorite-gabbros suite samples (Sawawin Complex), two meta-granite samples (Ifal suite) and five Zuhd alkali granite samples. The obtained data indicate traces of high to moderate level of deformation in the meta-granite and metavolcano-sedimentary rocks. The axial ratios along the XZ section range from 1.70 to 4.80 for the R_f/? method and from 1.50 to 4.50 for the Fry method. A sub-vertical trend of short axes in association with sub-horizontal foliation is also observed. These informations allow us to conclude that a finite strain in the deformed granitic rocks is of the same order of magnitude as in the metavolcano-sedimentary rocks. The contacts between the metavolcano-sedimentary and granitic rocks in Tayyib al Ism area were formed during the granitic intrusions along some of the faults under brittle to semi-ductile deformation conditions. These faults have significantly influenced the geometry and style of rifting in the Red Sea during the Neogene. The finite strain was accumulated in the area during the process of deformation, which superimpose the already existed nappe structure. It indicates that the nappe contacts formed during the accumulation of finite strain. In addition to finite strain analysis, band ratio images (3/1, 5/3, 7/5) and Principal Component Analysis (PCA) technique have been used, which proved effective in mapping geological and structural features of various rock bodies exposed in the study area.     

线性构造与环状构造在工程地质研究中的实践意义

在卫星像片上,众多线性影像与环状影像显示清晰。研究证明,这些线性影像和环形影像均是地表一些线性构造和环形构造的映像,而这些线性、环形构造与矿产、水、油气矿藏形成分布、地震活动、工程地质及地壳稳定性等,都有着密切的关系。因此,进一步深入研究线性构造、环状构造,具有重要的实际意义。     

Resolution vs. image quality in pre-tsunami imagery used for tsunami impact models in Aceh,Indonesia

Land cover roughness coefficients (LCRs) have been used in multivariate spatial models to test the mitigation potential of coastal vegetation to reduce impacts of the 2004 tsunami in Aceh, Indonesia. Previously, a Landsat 2002 satellite imagery was employed to derive land cover maps, which were then combined with vegetation characteristics, i.e., stand height, stem diameter and planting density to obtain LCRs. The present study tested LCRs extracted from 2003 and 2004 Landsat (30 m) images as well as a combination of 2003 and 2004 higher spatial resolution SPOT (10 m) imagery, while keeping the previous vegetation characteristics. Transects along the coast were used to extract land cover, whenever availability and visibility allowed. These new LCRs applied in previously developed tsunami impact models on wave outreach, casualties and damages confirmed previous findings regarding distance to the shoreline as a main factor reducing tsunami impacts. Nevertheless, the models using the new LCRs did not perform better than the original one. Particularly casualties models using 2002 LCRs performed better (δAIC > 2) than the more recent Landsat and SPOT counterparts. Cloud cover at image acquisition for Landsat and low area coverage for SPOT images decreased statistical predictive power (fewer observations). Due to the large spatial heterogeneity of tsunami characteristics as well as topographic and land-use features, it was more important to cover a larger area. Nevertheless, if more land cover classes would be referenced and high resolution imagery with low cloud cover would be available, the full benefits of higher spatial resolution imagery used to extract more precise land use roughness coefficients could be exploited.     

Land use change detection based on multi‐date imagery from different satellite sensor systems

An empirical study was performed assessing the accuracy of land use change detection when using satellite image data acquired ten years apart by sensors with differing spatial resolutions. Landsat/Multi‐spectral Scanner (MSS) with Landsat/Thematic Mapper (TM) or SPOT/High Resolution Visible (HRV) multi‐spectral (XS) data were used as a multi‐data pair for detecting land use change. The primary objectives of the study were to: (1) compare standard change detection methods (e.g. multi‐date ratioing and principal components analysis) applied to image data of varying spatial resolution; (2) assess whether to transform the raster grid of the higher resolution image data to that of the lower resolution raster grid or vice‐versa in the registration process: and (3) determine if Landsat/TM or SPOT/ HRV(XS) data provides more accurate detection of land use changes when registered to historical Landsat/MSS data.

Ratioing multi‐sensor, multi‐date satellite image data produced higher change detection accuracies than did principal components analysis and is useful as a land use change enhancement technique. Ratioing red and near infrared bands of a Landsat/MSS‐SPOT/HRV(XS) multi‐date pair produced substantially higher change detection accuracies (～10%) than ratioing similar bands of a Landsat/MSS ‐ Landsat/TM multi‐data pair. Using a higher‐resolution raster grid of 20 meters when registering Landsat/MSS and SPOTZHRV(XS) images produced a slightly higher change detection accuracy than when both images were registered to an 80 meter raster grid. Applying a “majority”; moving window filter whose size approximated a minimum mapping unit of 1 hectare increased change detection accuracies by 1–3% and reduced commission errors by 10–25%.     

Evaluation et representation des erreurs sur les deformations d'un reseau geodesique: Utilisation de la methode de Monte Carlo

Résumé Le problème de la comparison des données obtenues à différentes époques sur un réseau geódésique pour en déduire les déformations subies par ce réseau au cours du temps est discuté, et conduit à proposer un mode de représentation simultané des déformations et des erreurs, utilisant les tenseurs de déformations classiques avec une méthode de Monte Carlo permettant de simuler un grand nombre de séries de mesures.

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The repetition of geodetic measurements is employed in many cases to monitor ground deformations, and is widely used for civil engineering, geodynamics and slope instabilities studies. Generally the networks used are small and the main problem to solve is how to detect stable zones, i.e. where the signal/noise ratio of the deformation measurements are below unity. This is commonly done using statistical tests. We present here a new tool, the simultaneous display of the deformations and their related errors, using a classical Monte Carlo methodology when computing strain tensors. Such a representation provides to non-specialists in a quit efficient way the significance level of the deformation patterns. Some examples show that even when statistical test show a poor confidence level, this methodology may give anyway in some situations the pattern of the deformation (but—obviously—not its amplitude).

     

Les mouvements de l'ecorce terrestre et leur observation geodesique

Conclusion Les exemples cités dans cet article et étudiés en Tchécoslovaquie montrent que sur la terre entière, se produisent des mouvements de l'écorce terrestre, horizontaux et verticaux, positifs et négatifs. En même temps on peut constater que ce sont les régions de tectonique jeune qui subissent ces mouvements et qu'ils s'y manifestent beaucoup plus intensivement (système slovaco—carpathien) que sur les masses de continent plus stables de l'écorce terrestre (Bohême et Moravie—Massif de Bohême) et que dans les régions séismiquement actives (bassin de Komarno en Slovaquie du Sud) leur direction peut changer. On peut supposer que ces mouvements provoquent certaines tensions dans les roches de l'écorce terrestre. Si une réserve suffisante d'énergie potentielle s'accumule en forme de tensions élastiques, il suffit d'une impulsion insignifiante (par ex. des dérangements aux lieux, fatigués tectoniquement, une altération du milieu minier par l'exploitation, etc..) pour transformer l'énergie potentielle accumulée en énergie cinétique. Ensuite se produisent des pressions des roches, des secousses et des dérangements différents de la structure des roches et par suite des mouvements secondaires. A. PELNAR conclut également que les secousses dans les mines de Pribram en Bohême peuvent être causées par des mouvements verticaux petits, mais bien impétueux des massifs, montagneux, moyennant quoi une énergie considérable se libère par un, écrasement des établissements miniers. Comme les mouvements mentionnés sont fonction du temps, les changements de tension et les déformations dans les roches et leurs conséquences se présentent comme une fonction du temps. L'importance des études de l'écorce terrestre est immense non seulement au point de vue scientifique (géologie, géodésie, géophysique), mais aussi au point de vue pratique (géologie d'ingénieur, industrie minière). L'étude détaillée des mouvements de l'écorce terrestre, de leurs causes, de l'énergétique, de l'action, de la connection et des conséquences de leurs marques permettra de résoudre un nombre de problèmes, parmi les autres même le problème des pressions et des couches montagneuses et aidera à résoudre maintes discussions à cet égard (voir par ex. la discussion entre le savant tchèque A. PELNAR et le spécialiste G. SPACKELLER sur la question de savoir si les secousses à Ostrava sont causées par les dernières manifestations du plissement varisque ou si elles sont provoquées par l'exploitation des mines ou toute autre cause inconnue. Les mouvements du groupe B joueront aussi un r?le important dans la solution de ces problèmes.     

Evaluation of multisensor data for delineating salt affected soils in arid rajasthan

The Landsat (MSS and TM), SPOT (PLA and MLA) and IRS (LISS-I and LISS-II) images of crop free period (April, May), rainfed crop (October) and rabi irrigated crop (January, February) have been evaluated for their capabilities of mapping (1) primary salt affected soils: (slightly, moderately and severely) (2) saline water irrigated saline soils, (3) sodic water irrigated sodic soils and (4) salt affected soils due to tank seepage in the arid region of Rajasthan. The moderately and severe salt affected soils could be mapped with Landsat, (IRS LISS-I) and SPOT, images of any season. However, the summer season imagery provided maximum extent of salt affected soils. The LISS-II imagery also provided delineation of slightly salt affected soils in addition to the moderate and severely salt affected soils. The delineation of saline and sodic water irrigated areas was possible by using Landsat False Colour Composite for the January month by their characteristic reflectance, existing cropping pattern and the quality of irrigation water being used in the area. The IRS (LISS-II) and SPOT PLA images for the May month were also used for mapping of saline and sodic water irrigated soils.     

SPOT DATA EVALUATION AND USE AT INSTITUT GÉOGRAPHIQUE NATIONAL, FRANCE

Since the launch of SPOT, Institut Géographique National, France has carried out several investigations concerned with in-flight evaluation, research operations and the setting up of production flowlines. The aims of assistance to data bank establishment, revision of existing maps and image map and thematic map production have now been achieved for the most part. Some procedures are already operational, including image product making, photogrammetry on SPOT images, classifications on image processing systems, manual information retrieval and image map production. Moreover, various research operations are virtually complete, including automatic correlation, composite processes between aerial photographs and SPOT images, quite promising mathematical morphology associated with expert systems for retrieving linear or complex textured (built up area) elements, and manual cartography on image processing system. These results confirm the great benefits of SPOT system capabilities and the characteristics of flexibility, accuracy and reliability. The Photogrammetric Society and the Remote Sensing Society held a one-day symposium at Burlington House, London on 11th November, 1987. The SPOT (Système Probatoire d'observation de la Terre) satellite had then been operational for 18 months and many organisations had been working with the data. This symposium reviewed the operation of the satellite and studies which had been carried out for mapping and for thematic applications. Six of the symposium papers are published here. It is expected that other papers from the symposium will be published in the International Journal of Remote Sensing.     

Relative suitability of indices derived from Landsat ETM+ and SPOT 5 for detecting fire severity in sagebrush steppe

Remote sensing indices of burn area and fire severity have been developed and tested for forest ecosystems, but not sparsely vegetated, desert shrub-steppe in which large wildfires are a common occurrence and a major issue for land management. We compared the performance of remote sensing indices for detecting burn area and fire severity with extensive ground-based cover assessments made before and after the prescribed burning of a 3 km² shrub-steppe area. The remote sensing indices were based on either Landsat 7 ETM+ or SPOT 5 data, using either single or multiple dates of imagery. The indices delineating burned versus unburned areas had better overall, User, and Producer's accuracies than indices delineating levels of fire severity. The Soil Adjusted Vegetation Index (SAVI) calculated from SPOT had the greatest overall accuracy (100%) in delineating burned versus unburned areas. The relative differenced Normalized Burn Ratio (RdNBR) using Landsat ETM+ provided the highest accuracies (73% overall accuracy) for delineating fire severity. Though SPOT's spatial resolution likely conferred advantages for determining burn boundaries, the higher spectral resolution (particularly band 7, 2.21 μm) of Landsat ETM+ may be necessary for detecting differences in fire severity in sparsely vegetated shrub-steppe.     

Problems of bias in mapping linear landforms from satellite imagery

Remotely sensed images are an important data source for the mapping of glacial landforms and the reconstruction of past glacial environments. However the results produced can differ depending on a wide range of factors related to the type of sensors used and the characteristics of the landforms being mapped. This paper uses a range of satellite imagery to explore the three main sources of variation in the mapped results: relative size, azimuth biasing and landform signal strength. Recommendations include the use of imagery illuminated with low solar elevation, although an awareness of the selective bias introduced by solar azimuth is necessary. Landsat ETM+ imagery meets the requirements for glacial landform mapping and is the recommended data source. However users may well have to consider alternative data in the form of SPOT, Landsat TM or Landsat MSS images. Digital elevation models should also be considered a valuable data source.     

SPOT与TM图像的数字复合试验

陆地卫星TM图像含有丰富的光谱信息,SPOT全色波段图像数据分辨率较高,因此,如何将这两种图像数据有效地结合起来,在遥感应用领域中显得越来越重要。本文研究了SPOT和TM图像数据的数字复合方法。结果表明,复合后的图像提高了分辨率,增加了光谱信息。     

Development of a modified neural network-based land cover classification system using automated data selector and multiresolution remotely sensed data

Integrating multiple images with artificial neural networks (ANN) improves classification accuracy. ANN performance is sensitive to training datasets. Complexity and errors compound when merging multiple data, pointing to needs for new techniques. Kohonen's self-organizing mapping (KSOM) neural network was adapted as an automated data selector (ADS) to replace manual training data processes. The multilayer perceptron (MLP) network was then trained using automatically extracted datasets and used for classification. Two hypotheses were tested: ADS adapted from the KSOM network provides adequate and reliable training datasets, improving MLP classification performance; and fusion of Landsat thematic mapper (TM) and SPOT images using the modified ANN approach increases accuracy. ADS adapted from the KSOM network improved training data quality and increased classification accuracy and efficiency. Fusion of compatible multiple data can improve performance if appropriate training datasets are collected. This proved to be a viable classification scheme particularly where acquiring sufficient and reliable training datasets is difficult.     

Mapping trees in high resolution imagery across large areas using locally variable thresholds guided by medium resolution tree maps

Large area tree maps, important for environmental monitoring and natural resource management, are often based on medium resolution satellite imagery. These data have difficulty in detecting trees in fragmented woodlands, and have significant omission errors in modified agricultural areas. High resolution imagery can better detect these trees, however, as most high resolution imagery is not normalised it is difficult to automate a tree classification method over large areas. The method developed here used an existing medium resolution map derived from either Landsat or SPOT5 satellite imagery to guide the classification of the high resolution imagery. It selected a spatially-variable threshold on the green band, calculated based on the spatially-variable percentage of trees in the existing map of tree cover. The green band proved more consistent at classifying trees across different images than several common band combinations. The method was tested on 0.5 m resolution imagery from airborne digital sensor (ADS) imagery across New South Wales (NSW), Australia using both Landsat and SPOT5 derived tree maps to guide the threshold selection. Accuracy was assessed across 6 large image mosaics revealing a more accurate result when the more accurate tree map from SPOT5 imagery was used. The resulting maps achieved an overall accuracy with 95% confidence intervals of 93% (90–95%), while the overall accuracy of the previous SPOT5 tree map was 87% (86–89%). The method reduced omission errors by mapping more scattered trees, although it did increase commission errors caused by dark pixels from water, building shadows, topographic shadows, and some soils and crops. The method allows trees to be automatically mapped at 5 m resolution from high resolution imagery, provided a medium resolution tree map already exists.     

Neue Analyse der Chandler-Bewegung

Summary TheChandler movement is essentially an oscillation having an assumed period of the order of time of a double revolution of the moon’s nodes. The variation in its period is only apparent and relies upon a sudden change of phase which occurred at the beginning of 1928. If attention is paid to the residuals, a secondary oscillation with an 11-year period can be detected. This explains theWitting perturbations, and is possibly connected with the sun-spot cycle.

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Resumen El movimientoChandler es en su esencia un balanceo que tiene una duración admitida del órden de la doble revolución de los nodos de la Luna. La variabilidad de su periodo no es más que simulada, debido a un salto de fase situada en el comienzo del a?o 1928. Utilizando los residuos, se puede demostrar un balanceo suplementario de 11 a?os, que explica lasperturbacionésWitting y que está posiblemente relacionado con el periodo de las manchas solares.

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Résumé La période deChandler correspond, dans son essence, à un balancement ayant une durée présumée de l’ordre de la double révolution des nœuds de la Lune. La variabilité de sa période n’est que dissimulée et ceci grace à un saut de phase situé au commencement de l’année 1928. En utilisant les résidus, on peut démontrer un balancement supplémentaire de 11 ans, qui explique les perturbationsWitting, et qui est en liaison possible avec la période des taches solaires.

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Sommario Il movimento diChandler è essenzialmente un’oscillazione avente presumibilmente un periodo doppio della rivoluzione dei nodi lunari. La variabilità di questo periodo è soltanto apparente, in consequenza di un salto di fase situato al principio del 1928. Utilizzando i residui, si può mostrare un’oscillazione supplementare del periodo di 11 anni, che spiega la perturbazione diWitting e che sta forse in relazione con il periodo delle macchie solari.

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Communication présentée à l’Assemblée Générale de Bruxelles     

Regional mapping of the South Armorican shear zone (Brittany, France) using remotely sensed SPOT imagery

The South Armorican shear zone is one of the major occurrences of Variscan basement in Europe. The objectives of the study were to compile a lineament and a structural map from remotely sensed SPOT imagery. Transparent color films, enhanced by high-pass filtering and by stretching color composites, and spatial filtered images were analysed. The major structure mapped corresponds to a dextral transcurrent shear belt in which C and S axes have been described. Late Paleozoic and Tertiary fracturations truncate these structures. The localisation, extension and geometry of granite domes were also precised. Lastly, this study provides a good example of structural interpretation of a moderate-relief terrain using high-resolution SPOT imagery.     

基于多进制小波变换的遥感影像融合

首先介绍了遥感影像融合的理论和方法 ,然后在讨论多进制小波理论的基础上 ,提出了一种基于特征的多进制小波变换的影像融合算法 ,该算法根据待融合影像分辨率之比确定采用多进制小波 ,从而最大限度的利用了待融合影像的信息 ,防止影像信息的丢失。通过对具体影像的实验 ,证明融合后的影像最大限度地保留了待融合影像的光谱信息 ,同时提高了待融合影像的清晰度和空间分辨率。文中给出了SPOT全色影像与SPOT多光谱波段影像、SPOT全色影像与TM影像的融合结果 ,并与其他方法进行了比较 ,证明了本方法的优越性和自适应能力     

Morphostratigraphy and fan morphology of doon valley

In the present study analysis of Landsat MSS, TM and SPOT imagery and digital analysis of IRS LISS-1 data of Doon Valley was carried out. Various geomorphic features were identified and classified, morphostratigraphy of the area has been established. Main geomorphic units of the area are Mussoorie Hill Range (Denudational), Siwalik Hills (Structural), Remnant Hills (Residual). Siwalik Piedmont. Doon Piedmont, River Terraces and Flood Plain. Three large fan lobes are identified on Doon Piedmont deposits, viz., Western fan lobe, Central fan lobe and Eastern fan lobe. Average slope of these three fan lobes are 2°21′, 2°3′, and 1°24′ for the western, central and eastern fan lobes respectively. Western and central fan lobes have been affected by neotectonic activity which is reflected in transverse profiles.     

Early-season mapping of crops and cultural operations using very high spatial resolution Pléiades images

The aim of this study was to assess the contribution of very high spatial resolution (VHSR) Pléiades images to both early season crop identification and the mapping of bare soil surface characteristics due to cultural operations. The study region covering 21 km² is located west of the peri-urban territory of the Versailles plain and the Alluets plateau (Yvelines, France). About 100 cropped fields were observed on the ground synchronously with two Pléiades images of 3 and 24 April 2013 and one SPOT4 image of 2 April 2013. The GIS structuring of these field data along with vector information about field boundaries was used for delimitating both training and test zones for the support vector machine classifier with polynomial function kernel (pSVM). The pSVM was computed on the spectral bands and NDVI for both single-date Pléiades and the bi-temporal Pléiades pair. For the single-date classifications of crops, the overall per-pixel accuracy reached 87% for the SPOT4 image of 2 April (6 classes), 79% for the Pléiades image of 3 April (6 classes) and 82% for that of 24 April (7 classes). At the earlier date (2–3 April), the Pléiades image very well discriminated cultural operations (>77%, user’s or producer’s accuracies) as well as fallows and grasslands, while winter cereals and rapeseed were better discriminated by the SPOT4 image winter cereals (>70%, user’s or producer’s accuracies). As Pléiades images revealed within-field spatial variations of early phenological stages of winter cereals that could be critical for adjusting management of zones with delayed development during the growing season, they brought information complementary to multispectral images with high spatial resolution. For the bi-temporal Pléiades image, the overall per-pixel accuracy was about 80% (7 classes), winter crops, grasslands and fallows being very well detected while confusions occurred between spring barley at initial stages (2–3 leaves) and bare soils prepared for other spring crops. Using an additional validation field set covering ∼1/3 of the study area croplands, the crop map resulting from the bi-temporal Pléiades pair achieved correct crop prediction for about 89.7% of the validation fields when considering composite classes for winter cereals and for spring crops. Early-season Pléiades images therefore show a considerable potential for anticipating regional crop patterns and detecting soil tillage operations in spring.     

Field spectroradiometer and simulated multispectral bands for discriminating invasive species from morphologically similar cohabitant plants

One of the challenges in fighting plant invasions is the inefficiency of identifying their distribution using field inventory techniques. Remote sensing has the potential to alleviate this problem effectively using spectral profiling for species discrimination. However, little is known about the capability of remote sensing in discriminating between shrubby invasive plants with narrow leaf structures and other cohabitants with similar ecological niche. The aims of this study were therefore to (1) assess the classification performance of field spectroradiometer data among three bushy and shruby plants (Artemesia afra, Asparagus laricinus, and Seriphium plumosum) from the coexistent plant species largely dominated by acacia and grass species, and (2) explore the performance of simulated spectral bands of five space-borne images (Landsat 8, Sentinel 2A, SPOT 6, Pleiades 1B, and WorldView-3). Two machine-learning classifiers (boosted trees classification and support vector machines) were used to classify raw hyperspectral (n = 688) and simulated multispectral wavelengths. Relatively high classification accuracies were obtained for the invasive species using the original hyperspectral bands for both classifiers (overall accuracy, OA = 83–97%). The simulated data resulted in higher accuracies for Landsat 8, Sentinel 2A, and WorldView-3 compared to those computed for bands simulated to SPOT 6 and Pleiades 1B data. These findings suggest the potential of remote-sensing techniques in the discrimination of different plant species with similar morphological characteristics occupying the same niche.