572 research outputs found
UP4DREAM CAPACITY BUILDING PROJECT: UAS BASED MAPPING IN DEVELOPING COUNTRIES
UP4DREAM (UAV Photogrammetry for Developing Resilience and Educational Activities in Malawi) is a cooperative project cofounded by ISPRS between the Polytechnic University of Turin and the United Nations Children Fund (UNICEF) Malawi, with the support of two local Universities (Lilongwe University of Agriculture and Natural Resources, and Mzuzu University), and Agisoft LLC (for the use of their photogrammetry and computer vision software suite). Malawi is a flood-prone landlocked country constantly facing natural and health challenges, which prevent the country's sustainable socio-economic development. Frequent naturals shocks leave vulnerable communities food insecure. Moreover, Malawi suffers from high rates of HIV, as well as it has endemic malaria. The UP4DREAM project focuses on one of the drone project's critical priorities in Malawi (Imagery). It aims to start a capacity-building initiative in line with other mapping missions in developing countries, focusing on the realization and management of large-scale cartography (using GIS - Geographic Information Systems) and on the generation of 3D products based on the UAV-acquired data. The principal aim of UP4DREAM is to ensure that local institutions, universities, researchers, service companies, and manufacturers operating in the humanitarian drone corridor, established by UNICEF in 2017, will have the proper knowledge and understanding of the photogrammetry and spatial information best practices, to perform large-scale aerial data acquisition, processing, share and manage in the most efficient, cost-effective and scientifically rigorous way
TLS MODELS GENERATION ASSISTED BY UAV SURVEY
By now the documentation and 3D modelling activities of built heritage concern in an almost usual way terrestrial Lidar techniques (TLS, Terrestrial Laser Scanning), and large scale mapping derived by UAV (Unmanned Aerial Vehicle) survey. This paper refers an example of 3D survey and reality based modelling applied on landscape and architectural assets. The choice of methods for documentation, in terms of survey techniques, depends primarily on issues and features of the area.
The achieved experience, allow to consider that the easy handling of TLS has enabled the use in limited spaces among buildings and collapsed roofs, but the topographic measure of GCPs (Ground Control Points), neither by total station nor by GPS/RTK technique, was easily feasible. Even more than proving the ability of the integration of TLS and UAV photogrammetry to achieve a multi-source and multi-scale whole model of a village, the experience has been a test to experiment the registration of terrestrial clouds with the support of control points derived by UAV survey and finally, a comparison among different strategies of clouds registration is reported. Analysing for each approach a number of parameters (number of clouds registration, number of needed points, processing time, overall accuracy) the further comparisons have been achieved.
The test revealed that it is possible to decrease the large number of terrestrial control points when their determination by topographical measures is difficult, and it is possible to combine the techniques not only for the integration of the final 3Dmodel, but also to solve and make the initial stage of the drafting process more effective
Training of Crisis Mappers and Map Production from Multi-sensor Data: Vernazza Case Study (Cinque Terre National Park, Italy)
This aim of paper is to presents the development of a multidisciplinary project carried
out by the cooperation between Politecnico di Torino and ITHACA (Information
Technology for Humanitarian Assistance, Cooperation and Action). The
goal of the project was the training in geospatial data acquiring and processing for
students attending Architecture and Engineering Courses, in order to start up a
team of “volunteer mappers”. Indeed, the project is aimed to document the environmental
and built heritage subject to disaster; the purpose is to improve the capabilities
of the actors involved in the activities connected in geospatial data collection,
integration and sharing. The proposed area for testing the training
activities is the Cinque Terre National Park, registered in the World Heritage List since 1997. The area was affected by flood on the 25th of October 2011. According
to other international experiences, the group is expected to be active after
emergencies in order to upgrade maps, using data acquired by typical geomatic
methods and techniques such as terrestrial and aerial Lidar, close-range and aerial
photogrammetry, topographic and GNSS instruments etc.; or by non conventional
systems and instruments such us UAV, mobile mapping etc. The ultimate goal is
to implement a WebGIS platform to share all the data collected with local authorities
and the Civil Protection
DIRECT GEOREFERENCING APPROACHES FOR CLOSE-RANGE AND UAV PHOTOGRAMMETRY IN THE BUILT HERITAGE DOMAIN
Direct georeferencing uses onboard sensors to measure the position and orientation of the camera during image acquisition for photogrammetric applications. This approach aims to eliminate the use of traditional Ground Control Points (GCPs) in the photogrammetric process in order to reduce the costs and the time of the survey operations. The direct georeferencing technique involves integrating measurements from inertial measurement units (IMUs) and Global Navigation Satellite Systems (GNSS) data in order to evaluate the position and attitude of the camera with high accuracy (a few centimeters). In the Built Heritage survey domain, this approach is mainly followed by the employment of UAVs (Uncrewed aerial systems) platforms that are nowadays equipped with highly accurate systems able to evaluate the external parameters for the photogrammetric process. For terrestrial applications, few already achieved tests were performed; moreover, the sensors today available for extracting information from close-range acquisition systems are limited and sometimes under development. To evaluate the possibility offered by these new direct georeferencing tools, a test on the 3D ImageVector (REDcatch GmbH) has been performed. The results and the strategies followed will be presented and analyzed in order to understand better the accuracy and the potentiality of this new promising approach
Propriedades fĂsico-hĂdricas e Ăndice de qualidade dos solos no distrito de irrigação tabuleiros litorâneos do PiauĂ.
O objetivo desta pesquisa foi diagnosticar as propriedades fĂsico-hĂdricas como granulometria, densidade do solo, água disponĂvel Ă s culturas, Ăndice de degradação fĂsica dos solos, bem como os teores de matĂ©ria orgânica do Distrito de Irrigação Tabuleiros Litorâneos do PiauĂ, em ParnaĂba, PI..
Mezzi aerei non convenzionali a volo autonomo per il rilievo fotogrammetrico in ambito archeologico
I rilievi fotogrammetrici aerei sono generalmente costosi e permettono comunque di acquisire immagini con risoluzione limitata a causa delle quote a cui possono generalmente volare gli aerei attrezzati. Per questa ragione, sono stati sviluppati e verificati numerosi sistemi in grado di acquisire immagini digitali ad alta risoluzione per applicazioni fotogrammetriche a basso costo (palloni aerostatici, mongolfiere, aerei ed elicotteri ultraleggeri, ecc.): in questo ambito, i mezzi aerei non convenzionali a volo autonomo (in inglese Unmanned Aerial Vehicle, UAV) rappresentano una delle tecniche piĂą promettenti se dotati di camera digitale ad alta risoluzione.
In questo contributo, gli autori descrivono le modalità operative per l’acquisizione di immagini digitali a bassa quota mediante UAV multi-rotore e la loro successiva elaborazione per produrre, nel modo più automatico possibile, un supporto cartografico a grandissima scala (l’ortofoto solida di precisione) di ausilio a studi archeologici
Collective transport of droplets through porous media
The flow of deformable particles, such as droplets, dragged by a fluid,
through a network of narrow pores inside rocks or other porous media is key in
a range of applications, from enhanced oil recovery and water filtration to lab
on a chip sorting of cells. The collective dynamics and its impact on the flow
are poorly understood. Here, using droplets as a prototype, we show that
collective transport can occur for conditions under which a single particle
would get trapped at a pore channel. When a series of droplets gets trapped,
the fluids flow is affected significantly, leading to an increase of the
pressure difference across the pore channels, which in turn squeezes the
particles through the channels. We analyze the conditions for a single droplet
to flow through one pore and derive the corresponding Bond number. We also
obtain a rule for the collective flow of droplets in porous media
Physical properties and soil degration index in the "Plateau of Guadalupe irrigation district", PiauĂ state, Brazil.
The management of water and soil is an important aspect of sustainable agricultural production. Knowledge of the physical properties of the soil is essential for the characterization of the soil-water-plant interactions and also for the establishment of irrigation management, in accordance with soil and crop requirements. The objective of this study was to evaluate the physical properties i.e. that pertain to water content, granulometry, bulk density, along with the water retention curve and soil physical degradation index of the "Plateaus of Guadalupe Irrigation District", Piaui State, Brazil. Undisturbed and disturbed soil samples were collected in plots, randomly chosen, as well as in areas of initial preparation, at depths of 0 to 0.2 m and 0.2 to 0.4 m. The water retention curves were molded with suction pressure of -6, -10, -30, -100, -300, -500 and -1500 kPa and adjusted by the Genucthen model. There was an increase in clay levels of the soil depth. The bulk density showed lower values in the areas of initial preparation. The average available soil water was higher in the layer 0 to 0.2 m. Three plots presented problems with the soil physical degradation index, but in general, the soil had good physical conditions for cultivation
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