1,086 research outputs found
MULTI-TEMPORAL ANALYSIS OF LANDSCAPES AND URBAN AREAS
This article presents a 4D modelling approach that employs multi-temporal and historical aerial images to derive spatio-temporal information for scenes and landscapes. Such imagery represent a unique data source, which combined with photo interpretation and reality-based 3D reconstruction techniques, can offer a more complete modelling procedure because it adds the fourth dimension of time to 3D geometrical representation and thus, allows urban planners, historians, and others to identify, describe, and analyse changes in individual scenes and buildings as well as across landscapes. Particularly important to this approach are historical aerial photos, which provide data about the past that can be collected, processed, and then integrated as a database. The proposed methodology employs both historical (1945) and more recent (1973 and 2000s) aerial images from the Trentino region in North-eastern Italy in order to create a multi-temporal database of information to assist researchers in many disciplines such as topographic mapping, geology, geography, architecture, and archaeology as they work to reconstruct building phases and to understand landscape transformations (Fig. 1)
Underwater calibration of dome port pressure housings.
Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g.
archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to
the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional
optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the
most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the
manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and
decentering distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief
introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat
and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies
JOINT ALIGNMENT OF UNDERWATER AND ABOVE-THE-WATER PHOTOGRAMMETRIC 3D MODELS BY INDEPENDENT MODELS ADJUSTMENT
The surveying and 3D modelling of objects that extend both below and above the water level, such as ships, harbour structures, offshore platforms, are still an open issue. Commonly, a combined and simultaneous survey is the adopted solution, with acoustic/optical sensors respectively in underwater and in air (most common) or optical/optical sensors both below and above the water level. In both cases, the system must be calibrated and a ship is to be used and properly equipped with also a navigation system for the alignment of sequential 3D point clouds. Such a system is usually highly expensive and has been proved to work with still structures. On the other hand for free floating objects it does not provide a very practical solution. In this contribution, a flexible, low-cost alternative for surveying floating objects is presented. The method is essentially based on photogrammetry, employed for surveying and modelling both the emerged and submerged parts of the object. Special targets, named Orientation Devices, are specifically designed and adopted for the successive alignment of the two photogrammetric models (underwater and in air). A typical scenario where the proposed procedure can be particularly suitable and effective is the case of a ship after an accident whose damaged part is underwater and necessitate to be measured (Figure 1). The details of the mathematical procedure are provided in the paper, together with a critical explanation of the results obtained from the adoption of the method for the survey of a small pleasure boat in floating condition
Body Temperatures and Activity Patterns of Tasmanian Devils (Sarcophilus harrisii) and Eastern Quolls (Dasyurus viverrinus) through a Subalpine Winter
During a field study of carnivorous dasyurid marsupials in subalpine Tasmania, the trapping success for Tasmanian devils (Sarcophilus harrisii), but not for spotted-tailed quolls (Dasyurus maculatus) or eastern quolls (Dasyurus viverrinus), was significantly lower when winter weather conditions turned to sleet or snow or when deep snow lay on the ground. This field study was instigated to determine if devils and eastern quolls spend more time in burrows in severe weather conditions and if they enter torpor. Torpor is known to occur in eutherian mammals as large as devils and in a similar-sized congeneric marsupial, the western quoll (Dasyurus geoffroyi). Using radiotelemetry, body temperatures of Tasmanian devils and eastern quolls ranging freely in their natural habitat were monitored throughout winter. Neither species was observed in torpor, even under prolonged severe weather conditions, and the number of hours spent active did not differ between summer and winter or between moderate and severe winter weather conditions. Body temperatures averaged 36.5 degrees C (SD = 0.079, range of 33.5 degrees -38.6 degrees C) for the three male eastern quolls and 35.7 degrees C (SD = 0.575, range of 31.3 degrees - 37.5 degrees C) for the four (male and female) devils. A diel cycle in body temperature occurred in both species; temperatures rose each evening when animals became active, remained high throughout the night despite ambient temperatures falling to the diel minima, and were lower during the day when the individuals were inactive in dens. The amplitude of this cycle was greater in eastern quolls (1.1 degrees C, SD = 0.142) than in devils (0.6 degrees C, SD = 0.252)
Knowledge and valorization of historical sites through 3D documentation and modeling
The paper presents the first results of an interdisciplinary project related to the 3D documentation, dissemination, valorization and digital access of archeological sites. Beside the mere 3D documentation aim, the project has two goals: (i) to easily explore and share via web references and results of the interdisciplinary work, including the interpretative process and the final reconstruction of the remains; (ii) to promote and valorize archaeological areas using reality-based 3D data and Virtual Reality devices. This method has been verified on the ruins of the archeological site of Pausilypon, a maritime villa of Roman period (Naples, Italy). Using Unity3D, the virtual tour of the heritage site was integrated and enriched with the surveyed 3D data, text documents, CAAD reconstruction hypotheses, drawings, photos, etc. In this way, starting from the actual appearance of the ruins (panoramic images), passing through the 3D digital surveying models and several other historical information, the user is able to access virtual contents and reconstructed scenarios, all in a single virtual, interactive and immersive environment. These contents and scenarios allow to derive documentation and geometrical information, understand the site, perform analyses, see interpretative processes, communicate historical information and valorize the heritage location
Managing benign tracheal stenosis during COVID-19 outbreak
If elective surgery has been recommended to be postponed
some diseases could potentially become life-threatening
and cannot be delayed. Among these conditions, tracheal idiopathic stenosis, primary caused by endotracheal intubation
or tracheostomy, usually become symptomatic when reach
50% obstruction.
Endoscopic procedures could be considered as frst
treatment in selected patients after stenosis evaluation, such
as non-complex stenosis with low grade of cartilage involvement or tracheomalaci
Wintertime transport processes in the Gulf of Naples investigated by HF radar measurements of surface currents
Transport processes play a fundamental role in regulating the water renewal in coastal systems. The Gulf of Naples (Southern Tyrrhenian Sea) is a highly urbanised area, receiving pollutant discharges and terrestrial inputs that
may reside inside the basin. For this reason, understanding the processes governing coast-offshore transport is of paramount importance for the welfare of the ecosystem
and the sustainable exploitation of environmental resources. In this work, we analyse the wind-driven transport over lags of three days in winter reconstructing
the basin scale surface circulation by means of
High-Frequency radars and evaluating its dependence on wind circulation. Simulations of particle exchange between a
coastal and an offshore area have been carried out, outlining the strong relationship between particle fate and circulation structures. Results are interpreted in terms of
residence times and possible aggregative areas in the Gulf of Naples
Consumer perception of food variety in the UK: an exploratory mixed-methods analysis
Background: ‘Food variety’ is a key term that is frequently used in dietary guidelines around the world. Consuming a variety of foods – be it within a meal, across meals, or as part of the whole diet – is one factor that has been shown to increase food intake. However, little is known about consumer understanding of variety, and this may be a potential barrier to the success of dietary guidelines in today’s ‘obesogenic’ environment. This research sought to explore 1) consumer recognition of different forms of variety, and 2) consumer definitions of variety. Methods: In an online study (N = 240), participants were asked to discuss a range of photographs depicting different forms of variety, and to directly define the term ‘food variety’. They were unaware of the research aim. Results: Using a mixed methods approach, directed content analysis of these data showed that individuals referenced multiple forms of variety in the presence of food photographs. However, when asked to define variety, participants tended to only discuss variety in the context of the whole diet. Conclusions: These findings emphasise a need to educate consumers about variety to encourage adherence to dietary guidelines and help consumers better manage their own food intake
Underwater photogrammetry for 3D modeling of floating objects: The case study of a 19-foot motor boat
3D modeling of floating or semi-submerged objects is a challenging and attractive task for the marine industry especially if the manufacturing of components that have to be replaced or repaired after a damage is necessary or the ship itself has to be converted. Up to now the 3D reverse engineering of ships has required docking operations to carry out a geodetic or photogrammetric survey with high costs for shipowners. In this paper an innovative 3D acquisition method for digital recording of floating objects is presented. The method is based on digital photogrammetry both underwater and terrestrial. Preliminary tests are presented for the case study of a 19-foot motor boat. Two surveys of the boat in floating conditions are carried out and then joined by means of special rigid orientation devices built ad hoc
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