1,721,003 research outputs found
Evaluation of MODIS data for mapping oil slicks - the deepwater horizon oil spill case
Full text linkModerate Resolution Imaging Spectroradiometer (MODIS) multispectral imagery is used for oil spills mapping as an integration to radar data. MODIS images of the northern Gulf of Mexico (USA) are analyzed to study the sea anomalies from visible to thermal infrared in order to detect a reported oil slick. A simple Fluorescence/Emissivity Index and RGB false color bands combination are applied to detect fluorescence and emissivity anomalies due to oil spills in particular sun glint conditions. A monitoring system of sea surface may be built using high temporal resolution imagery as MODIS data. Applying the proposed index and RGB bands combination, also suitable on night-time overpasses, it’s possible to further increase the availability of clouds free images using optical sensors
Mapping large-scale microseepage signals for supporting oil and gas exploration in new ventures
No full textOptical remote sensing is emerging among non-conventional geophysical methods for oil & gas exploration and mineral prospecting. Complementary to all traditional technologies such as seismic, magnetic, gravity or electric methods, multispectral imaging is able to detect long-term biochemical and geochemical environmental alterations, known as microseepage effect, produced by invisible small fluxes of light hydrocarbons migrating from the underground deposits to the surface. This paper describes a case study where satellite multispectral data were used to detect large-scale microseepage signals nearby Lake Turkana (Republic of Kenya). The satellite analysis highlighted the presence of invisible surface signals on top of several oilfields discovered only many years after the image collection
Detection of moving vehicles with WorldView-2 satellite data
No full textTraffic monitoring in urban areas is a complex issue and recent Remote Sensing technologies can play an important role in planning and monitoring the urban environment. In this study a semi-automatic object-oriented workflow was designed to detect moving vehicles and their speed from single pass WorldView-2 multispectral data. The time lag in data recording between each spectral band causes a small image displacement of moving objects and this discrepancy is used to detect moving vehicles, their speed and direction of travel. The method proposed was applied to a very complex study area in the historical core of city of Multan, in the Pakistani southern province of Punjab, where very small and extremely dense built-up old style houses are mixed together with narrow roads and bazaar streets. First results show interesting applications of this new technology, with achieved accuracies of about 67% evaluated comparing automatic detection vs. manual interpretation
Integration of COSMO-SkyMed and GeoEye-1 Data With Object-Based Image Analysis
Full text linkThis paper describes the potentialities of data integration of high spatial resolution multispectral and single-polarization X-band radar for Object Based Image Analysis (OBIA) using already available algorithms and techniques. GeoEye-1 multispectral images (0.5/2.0 m) and COSMO-SkyMed stripmap images (3.0 m) were collected over a complex test site in the Venetian Lagoon, made up of an intricate mixture of settlements, cultivations, channels, roads, and marshes. The validation confirmed that the integration of optical and radar data substantially increased the thematic accuracy (about 20-30% for overall accuracy and about 25-35% for k coefficient) of multispectral data and, unlike the outcomes of some new researches, also confirmed that with appropriate pre-processing traditional OBIA could be applied also to X-band radar data without the need of developing ad hoc algorithms
Optimal spectral band configuration for forest land-cover classification of hyperspectral data: a study for the Italian-Canadian Joint Hyperspectral Mission
No full textIn 2006 the Italian and the Canadian Space Agencies started a collaboration to evaluate the feasibility of the Joint Hyperspectral Mission (JHM), a new mission for Earth Observation devoted to environmental applications. JHM was designed to operate with a 30 m resolution hyperspectral sensor able to collect 210 narrow spectral bands in the range of 400-2500 nm. This paper presents a study carried on for the Italian Space Agency during Phase A, aimed to suggest an optimal spectral setup for the land-cover key application. Just referring to the mapping of forest species, results on simulated JHM data suggested that an optimal configuration can be obtained using a 50 nm bandwidth
Multispectral technology for mining exploration in arid lands: a short review (tecnologia multispettrale per l’esplorazione d’idrocarburi in ambienti aridi: una breve review)
No full textA oggi non esistono stime attendibili sull’effettiva consistenza delle risorse d’idrocarburi e solamente poco più di un quarto dei bacini potenzialmente interessanti ai fini dell’esplorazione sono stati adeguatamente studiati. Anche le tecniche d’indagine più sofisticate spesso si rivelano inadeguate o contraddittorie e per questo motivo numerose compagnie petrolifere stanno valutando le potenzialità offerte da altre nuove tecnologie, come ad esempio il Telerilevamento multispettrale. Questa breve review descrive lo stato dell’arte nella ricerca di microseep d’idrocarburi in ambienti aridi mediante l’utilizzo di tecniche di Telerilevamento ottico multispettrale
Minimum noise fraction transform for improving the classification of airborne hyperspectral data: two case studies
No full textThis paper investigates the use of Minimum Noise Fraction (MNF) components to improve the spectral separability of two specific thematic classes in airborne hyperspectral imagery using Spectral Angle Mapper (SAM). Particularly, we compared trends on data distribution before and after MNF transform. Two different data sets recorded with the Multispectral Infrared Visible Imaging Spectrometer (MIVIS) were analyzed. In the first case study, the classification of MNF-transformed data led to an overall enhancement in mapping asbestos roofs. In the second case study, the classification of MNF-transformed data succeeded to distinguish between two different artificial lakes, whereas classification of original hyperspectral data failed. Overall, this study showed how the use of MNF as pre-processing could improve the capability to extract information from two different airborne hyperspectral data sets
Hierarchical classification of complex landscape with VHR pan-sharpened satellite data and OBIA techniques
Full text linkLand-cover/land-use thematic maps are a major need in urban and country planning. This paper demonstrates the capabilities of Object Based Image Analysis in multi-scale thematic classification of a complex sub-urban landscape with simultaneous presence of agricultural, residential and industrial areas using pan-sharpened very high resolution satellite imagery. The classification process was carried out step by step through the creation of different hierarchical segmentation levels and exploiting spectral, geometric and relational features. The framework returned a detailed land-cover/land-use map with a Cohen’s kappa coefficient of 0.84 and an overall accuracy of 85%
Supporting hydrocarbon exploration in new venture areas with optical remote sensing
Full text linkIn past time, exploration geologists mainly used Earth Observation systems for basin-wide analysis of gravimetry, magnetomerty, structural faults, lithology and land-cover. After two decades of research, nowadays multispectral and hyperspectral remote sensing represent a cutting-edge technology in the oil and gas industry. The application fields of optical remote sensing not only range from the monitoring of the oilfields to the evaluation of pollution, but also to hydrocarbon exploration. With reference to exploration activities, the observation of the territory from above into several different wavelengths is able to supply inestimable geophysical information related to the microseepage effect, different and complementary to tradition geophysical methods.
It is almost accepted that many of the oil and gas fields leak light hydrocarbon gases along nearly vertical pathways and, thus, their detection with multi/hyperspectral imaging can support the detection of active petroleum systems. Indeed, several independent oil companies are using satellite and airborne observations for reducing exploration risks in new venture areas and for optimizing their seismic surveys.
This study shows some examples of microseepage-related geochemical and geobotanical alterations detected in several different environments, from sandy desert to vegetated savannah, both using airborne hyperspectral data and multispectral satellite time series. All the examples analyze real onshore concession blocks in Africa and Asia and results clearly show a correlation between the spectral signals recorded form remote with in situ measures, well logs, the knowledge of the subsurface and the position of known oilfields
Fusione di dati COSMO-SkyMed e Geoeye-1 per la classificazione del land cover nella laguna di Venezia
Full text linkIl presente studio si inquadra nel Programma di ricerca “The demonstration of the COSMO-SkyMed capabilities and exploitation for science and civilian applications” dell’Agenzia Spaziale Italiana e ha lo scopo di dimostrare le potenzialità dell’utilizzo congiunto di dati ottici multispettrali e SAR in banda X ad alta risoluzione geometrica per la classificazione del land-cover/land-use. Un primo test di classificazione tematica con dati GeoEye-1 e COSMO-SkyMed è stato realizzato nella zona litoranea circostante la città di Venezia, scelta per la presenza di un land-cover ricco e unico nel suo genere. Il confronto tra le classificazioni pixel-based e object-based mostrano che come la seconda dia sempre risultati più accurati. Inoltre, l’aggiunta del dato radar a quello ottico è ininfluente nel caso della classificazione pixel-based (si passa da una Overall Accuracy di 68,4% a 69,4%) mentre produce un incremento di accuratezza di circa il 15% nel caso dell’OBIA (si passa da una Overall Accuracy di 73,0% a 88,8%)
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