49 research outputs found

    VITO Remote Sensing

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    Monitoring inland waters with the APEX sensor, a wavelet approach

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    In this study a new curve fitting approach is presented to derive TSM, CHL and CDOM concentrations in inland and coastal waters from water leaving-reflectance spectra. The approach is based on the wavelet transform and is tested on simulated water-leaving reflectance spectra. For simulations SIOPS and water concentrations, representative for the Scheldt river, were used. The results shown that the approach is less sensitive to errors in the atmospheric correction or specific sensor noise. The idea is based on the development of a new minimization criteria for curve fitting. Instead of minimizing the difference between modeled and measured spectra using a simple RMSE, the RMSE is now combined with specific wavelet features. Several types of errors and noise are added to the simulated spectra to find robust features. Two minimization criteria were found which are almost insensitive to a white error and less sensitive to adjacency effects

    VITO combineert sensorplatformen met aardobservatie voor een betere monitoring van water

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    De huidige systemen om de toestand van het water op te volgen, voldoen vaak niet aan de noden van waterbeheerders, baggeraars, waterbedrijven, havenbeheerders, enzovoort. De data schieten tekort in kwaliteit en kwantiteit. Daarom ontwikkelt VITO een monitoringssysteem dat geautomatiseerde sensoren op onbemande vaartuigen combineert met aardobservatie: SAVEWATER. Ook het beschikbaar stellen van de data maakt deel uit van dit systeem. Het project wordt samen met de Europese ruimtevaartorganisatie ESA uitgewerkt

    A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters

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    In ocean colour remote sensing, the use of Near Infra Red (NIR) spectral bands for the retrieval of Total Suspended Matter (TSM) concentration in turbid and highly turbid waters has proven to be successful. In extremely turbid waters (TSMN 100 mgL−1) however, these bands are less sensitive to increases in TSM. Here it is proposed to use Short Wave Infra Red (SWIR) spectral bands between 1000 and 1300 nm for these extreme cases. This SWIR spectral region is subdivided into two regions, SWIR-I (1000 nm to 1200 nm) and SWIR-II (1200 nm to 1300 nm) which correspond to local minima in the pure water absorption spectrum. For both spectral regions the water reflectance signal was measured in situ with an ASD spectrometer in three different extremely turbid estuarine sites: Scheldt (Belgium), Gironde (France), and Río de la Plata (Argentina), along with the TSMconcentration.A measurable water reflectance was observed for all sites in SWIR-I, while in the SWIR-II region the signal was not significant compared to the Signal-to-Noise Ratio (SNR) of current Ocean Colour (OC) sensors. For the spectral band at 1020 nm (present in Ocean and Land Colour Instrument ? OLCI, onboard Sentinel-3) and at 1071 nm, an empirical single band TSM algorithm is defined which is valid for both the Gironde and Scheldt estuarine sites. This means that a single algorithm can be applied for both sites without expensive recalibration.The relationship between TSM and SWIR reflectance at 1020 and 1071 nm is linear and did not show any saturation for the concentrations measured here (up to 1400 mg L−1), while saturation was observed for the NIR wavelengths, as expected. Hence, for extremely turbid waters it is advised to switch from NIR to SWIR-I wavelengths to estimate TSM concentration. This was demonstrated for an airborne hyperspectral dataset (Airborne Prism Experiment, APEX) from the Gironde estuary having several spectral bands in the SWIR-I. The empirical single band SWIR TSM algorithm was applied to the atmospherically corrected scene providing a TSM concentration map of the Gironde from mouth to more upstream with concentrations expected in this region ranging from a few to several hundreds mg L−1. These results, i.e. the existence of a single relationship for the Scheldt and Gironde, not showing any decrease of sensitivity, highlights the importance of having SWIR bands in future ocean colour sensors for studying extremely turbid rivers, coastal areas and estuaries in the world. A further implication of these results is that there is a TSMlimit for application of atmospheric correction algorithms which assume zero SWIR marine reflectance. That limit is defined here as function of wavelength and sensor noise level.Fil: Knaeps, E.. Flemish Institute for Technological Research (VITO); BélgicaFil: Ruddick, K. G.. Flemish Institute for Technological Research ; BélgicaFil: Doxaran, D.. Laboratoire d; FranciaFil: Dogliotti, Ana Inés. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Nechad, B.. Royal Belgian Institute for Natural Sciences (RBINS); BélgicaFil: Raymaekers, D.. Flemish Institute for Technological Research; BélgicaFil: Sterckx, S.. Flemish Institute for Technological Research; Bélgic

    Alternatieve stortstrategie voor de Westerschelde : Voortzetting monitoringsprogramma proefstorting walsoorden LOT 2: Ecologische monitoring

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    Contains fulltext : 35149.pdf (publisher's version ) (Open Access)148 p

    Airborne Drones for Water Quality Mapping in Inland, Transitional and Coastal Waters—MapEO Water Data Processing and Validation

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    Using airborne drones to monitor water quality in inland, transitional or coastal surface waters is an emerging research field. Airborne drones can fly under clouds at preferred times, capturing data at cm resolution, filling a significant gap between existing in situ, airborne and satellite remote sensing capabilities. Suitable drones and lightweight cameras are readily available on the market, whereas deriving water quality products from the captured image is not straightforward; vignetting effects, georeferencing, the dynamic nature and high light absorption efficiency of water, sun glint and sky glint effects require careful data processing. This paper presents the data processing workflow behind MapEO water, an end-to-end cloud-based solution that deals with the complexities of observing water surfaces and retrieves water-leaving reflectance and water quality products like turbidity and chlorophyll-a (Chl-a) concentration. MapEO water supports common camera types and performs a geometric and radiometric correction and subsequent conversion to reflectance and water quality products. This study shows validation results of water-leaving reflectance, turbidity and Chl-a maps derived using DJI Phantom 4 pro and MicaSense cameras for several lakes across Europe. Coefficients of determination values of 0.71 and 0.93 are obtained for turbidity and Chl-a, respectively. We conclude that airborne drone data has major potential to be embedded in operational monitoring programmes and can form useful links between satellite and in situ observations

    Aerobic fitness is a potential crucial factor in protecting paralympic athletes with locomotor impairments from atherosclerotic cardiovascular risk

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    PurposeTo test the hypothesis that aerobic fitness is inversely related to the risk of atherosclerotic cardiovascular disease (ACVD) in athletes with locomotor impairments deriving from health conditions, such as spinal cord injury (SCI), lower limb amputation, cerebral palsy, poliomyelitis, and other health conditions different from the previous ones.MethodsA total of 68 male athletes who competed in either summer or winter Paralympic games were divided in two health conditions groups (35 with SCI, mean age 37.28.0 years, and 33 with different health conditions, mean age 37.89.9 years) and in four sport type groups (skill, power, intermittent-mixed metabolism-and endurance). They were evaluated through anthropometric and blood pressure measurements, laboratory blood tests, and graded cardiopulmonary maximal arm cranking exercise test, with oxygen uptake peak (VO2peak) measurement. Cardiovascular risk profile was assessed in each athlete.ResultsThe prevalence of ACVD-risk factors in the overall population was 20.6% for hypertension; 47% and 55.9% for high values of total and LDL cholesterol, respectively; 22.1% for reduce glucose tolerance; and 8.8% for obesity. No difference was found between athletes with and without SCI, while the prevalence of obesity was significantly higher in those practicing skill sports (22.7%, p=0.035), which was the sport type group with Paralympic athletes with the lowest VO2peak (22.5 +/- 5.70 ml kg(-1) min(-1)). VO2peak was lower in athletes with SCI than those with different health conditions (28.6 +/- 10.0 vs 33.6 +/- 8.9 ml kg(-1) min(-1)p=0.03), and in those with 3-4 risk factors (19.09 +/- 5.34 ml kg(-1) min(-1)) than those with 2 risk factors (27.1 +/- 5.50 ml kg(-1) min(-1)), 1 risk factor (31.6 +/- 8.55 ml kg(-1) min(-1)), or none (36.4 +/- 8.76 ml kg(-1) min(-1)) (p<0.001).ConclusionsThe present study suggests that having higher VO2peak seems to offer greater protection against ACVD in individuals with a locomotor impairment. Prescribing physical exercise at an intensity similar to that of endurance and intermittent sports should become a fundamental tool to promote health among people with a locomotor impairment.Open access funding provided by Universita degli Studi dell'Aquila within the CRUI-CARE Agreement
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