Search publications of the members of the Royal Belgian institute of natural Sciences
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Aerial imagery and structure-from-motion based DEM reconstruction of region-sized areas (Sierra Arana, Spain and Namur Province, Belgium) using an high-altitude drifting balloon platform.
- A new type of untethered balloon based mapping platform allows affordable remote sensing applications from higher altitudes and with a greater range and payload capacity than common motorized UAV’s. The airborne device, called “Stratochip”, is based on a dual helium balloons configuration. At a defined altitude (comprised between 1000 and 30000m), the first balloon is released, drastically reducing the platform climbing rate. The payload (up to 10kg) can then drift in a sub-horizontal trajectory until it leaves a pre-defined area of interest. Leaving the pre-defined area, the second balloon is released and the payload is recovered after a parachute landing. The predicted flight path of the Stratochip, launch site and surveyed area are calculated using both forecasted (NOAA model) and real-time (inborne instruments) meteorological data, along with the physical parameters of the balloons and parachute. The predicted recovery area can also be refined in real-time to secure and facilitate equipment retrieval. In this study, we present the results of two cartographic campaigns made in Belgium (Famennian outcrops near Beauraing, Namur Province) and Spain (karstic field in the Eastern part of Sierra Arana, Granada region). Those campaigns aimed to test the usability of the Stratochip to survey a large area at medium altitudes (3000m-8000m) and produced an updated Digital Elevation Model and orthophoto mosaic of those regions. For that purpose, the instrument installed in the Stratochip payload was constituted of a digital camera stabilized with two IMU’s and two brushless motors. An automated routine then tilted the camera at predefined angles while taking pictures of the ground. This technique allowed to maximize the photogrammetric information collected on a single pass flight, and improved the DEM reconstruction quality, using structure-from-motion algorithms. Three sets of data (DEM + orthophoto) were created from those campaigns, using pictures sets collected a different elevations. A 1m/pixel ground resolution set covering an area of about 200km² and mapping the eastern part of the Sierra Arana (Andalucía, Spain) includes a kartsic field directly to the south-east of the ridge and the cliffs of the “Riscos del Moro”. A 4m/pixel ground resolution set covering an area of about 900km² includes the landslide active Diezma region (Andalucía, Spain) and the water reserve of Francisco Abellan lake. The third set has a 3m/pixel ground resolution, covers about 100km² and maps the Famennian rocks formations, known as part of “La Calestienne”, outcropping near Beauraing and Rochefort in the Namur Province (Belgium). The DEM and orthophoto’s have been referenced using ground control points from satellite imagery (Spain, Belgium) and DPGS (Belgium). The quality of produced DEM were then evaluated by comparing the level and accuracy of details and surface artefacts between available topographic data (SRTM- 30m/pixel, topographic maps) and the three Stratochip sets. This evaluation showed that the models were in good correlation with existing data, and can be readily be used in geomorphology, structural and natural hazard studies.
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High-altitude free balloon trajectory predictions and applications in remote sensing
- A new type of untethered balloon based mapping platform allows affordable remote sensing applications from higher altitudes and with a greater range and payload capacity than common motorized UAV’s. The airborne device, called “Stratochip”, is based on a dual helium balloons configuration. At a defined altitude (comprised between 1000 and 30000m), a GPS based controller automatically releases the first balloon, drastically reducing the ascent rate. The payload (up to 10kg) can then float in a sub-horizontal trajectory until it leaves a pre-defined area of interest. At this point, the second balloon is released and the payload is recovered after a parachute landing. The predicted flight path of the Stratochip, launch site and surveyed area are calculated using physical parameters of balloons and parachute, as well as sounding meteorological data (NOAA windgram model) and real-time flight rates, along with the. The predicted recovery area can also be refined in real-time to secure and facilitate equipment retrieval. The Stratochip was tested to survey large areas at medium altitudes (1500m-8000m) in mountainous areas (Sierra Nevada, Spain) and hilly landscapes (Belgium). In a few flights, the platform allowed to produce several hundred squares kilometers of Digital Elevation Models and orthophoto mosaics. For that purpose, the instrument installed in the Stratochip payload was constituted of a digital camera stabilized with two IMU’s and two brushless motors. An automated routine then tilted the camera at predefined angles while taking pictures of the ground. This technique allowed to maximize the photogrammetric information collected on a single pass flight, and improved the DEM reconstruction quality, using structure-from-motion algorithms. Recontructed DEM’s and orthophoto’s have been referenced using ground control points from satellite imagery (Spain, Belgium) and DPGS (Belgium). The quality of produced DEM were then evaluated by comparing the level and accuracy of details and surface artifacts with available topographic data. This evaluation showed good correlation with existing data, improved the detail level in some areas and can be readily be used in Geomorphology, Structural Geology and Natural Hazards studies.
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Geoarchaeological records in temperate European valleys: Quantifying the resource, assessing its potential and managing its future
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Where Earth Scientists meet Cleopatra: Geoarchaeology and Geoprospection of ancient landscapes.
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Sandy aeolian deposits from the Gent Formation (Flanders, Belgium): lithostratigraphy, geomorphology and age. XIX Inqua congress, Nagoya, Japan.
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Another candidate species of Pelomedusa (Testudines: Pelomedusidae) from the Democratic Republic of the Congo?
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An unusual juvenile coloration of the whip snake Dolichophis jugularis (Linnaeus, 1758) observed in Southwestern Anatolia, Turkey
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Revision of the genus Paraphamartania Engel with description of two new species and comments on the related Nearctic genus Cophura Osten Sacken (Diptera: Asilidae)
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Molecular systematics and undescribed diversity of Madagascan scolecophidian snakes (Squamata: Serpentes)
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The geography of snake reproductive mode: A global analysis of the evolution of snake viviparity
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A modelling study of the drift and fate of large oil spills in seven sub-regions of the North Sea and the English Channel
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BEAWARE II : Data Provision Report
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An independent study to assess and validate the shape and size of the Potentially Impacted Areas used in BEAWARE 2 – Qualitative results
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BEAWARE II : Review of the physical oceanography in the area of the Bonn Agreement
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Mons / Obourg : évaluation archéologique à l’emplacement de la nouvelle écluse, au lieu-dit « Les Wartons ».
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Grez-Doiceau-Grez-Doiceau: le site La Tène de « Gastuche » : résultats des fouilles et premières analyses.
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Hurdles in investigating UVB damage in the putative ancient asexual Darwinula stevensoni (Ostracoda, Crustacea)
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On the Strandesia obtusata/elliptica – lineage (Crustacea, Ostracoda, Cyprididae) in the alluvial valley of the upper Paraná River (Brazil), with the description of three new species
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Cryptic diversity in putative ancient asexual darwinulids (Crustacea: Ostracoda)
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Molecular analyses of ostracod flocks from Lake Baikal and Lake Tanganyika
