1,020 research outputs found
A 3d geoscience information system framework
Two-dimensional geographical information systems are extensively used in the geosciences to create and analyse maps. However, these systems are unable to represent the Earth's subsurface in three spatial dimensions. The objective of this thesis is to overcome this deficiency, to provide a general framework for a 3d geoscience information system (GIS), and to contribute to the public discussion about the development of an infrastructure for geological observation data, geomodels, and geoservices. Following the objective, the requirements for a 3d GIS are analysed. According to the requirements, new geologically sensible query functionality for geometrical, topological and geological properties has been developed and the integration of 3d geological modeling and data management system components in a generic framework has been accomplished. The 3d geoscience information system framework presented here is characterized by the following features: - Storage of geological observation data and geomodels in a XML-database server. According to a new data model, geological observation data can be referenced by a set of geomodels. - Functionality for querying observation data and 3d geomodels based on their 3d geometrical, topological, material, and geological properties were developed and implemented as plug-in for a 3d geomodeling user application. - For database queries, the standard XML query language has been extended with 3d spatial operators. The spatial database query operations are computed using a XML application server which has been developed for this specific purpose. This technology allows sophisticated 3d spatial and geological database queries. Using the developed methods, queries can be answered like: "Select all sandstone horizons which are intersected by the set of faults F". This request contains a topological and a geological material parameter. The combination of queries with other GIS methods, like visual and statistical analysis, allows geoscience investigations in a novel 3d GIS environment. More generally, a 3d GIS enables geologists to read and understand a 3d digital geomodel analogously as they read a conventional 2d geological map
Euclid preparation XXVI. The Euclid Morphology Challenge. Towards structural parameters for billions of galaxies
The various Euclid imaging surveys will become a reference for studies of
galaxy morphology by delivering imaging over an unprecedented area of 15 000
square degrees with high spatial resolution. In order to understand the
capabilities of measuring morphologies from Euclid-detected galaxies and to
help implement measurements in the pipeline, we have conducted the Euclid
Morphology Challenge, which we present in two papers. While the companion paper
by Merlin et al. focuses on the analysis of photometry, this paper assesses the
accuracy of the parametric galaxy morphology measurements in imaging predicted
from within the Euclid Wide Survey. We evaluate the performance of five
state-of-the-art surface-brightness-fitting codes DeepLeGATo, Galapagos-2,
Morfometryka, Profit and SourceXtractor++ on a sample of about 1.5 million
simulated galaxies resembling reduced observations with the Euclid VIS and NIR
instruments. The simulations include analytic S\'ersic profiles with one and
two components, as well as more realistic galaxies generated with neural
networks. We find that, despite some code-specific differences, all methods
tend to achieve reliable structural measurements (10% scatter on ideal S\'ersic
simulations) down to an apparent magnitude of about 23 in one component and 21
in two components, which correspond to a signal-to-noise ratio of approximately
1 and 5 respectively. We also show that when tested on non-analytic profiles,
the results are typically degraded by a factor of 3, driven by systematics. We
conclude that the Euclid official Data Releases will deliver robust structural
parameters for at least 400 million galaxies in the Euclid Wide Survey by the
end of the mission. We find that a key factor for explaining the different
behaviour of the codes at the faint end is the set of adopted priors for the
various structural parameters.Comment: Accepted by A&A. 30 pages, 23+6 figures, Euclid pre-launch key paper.
Companion paper: Euclid Collaboration XXV: Merlin et al. 2022 Minor
corrections after journal revie
Visual Analytics framework for borders of human mobility
This thesis illustrates and discusses the design and development procedures of Mobility Atlas, a small web framework for interactive and visual analytics applied on a real-life situation such as Human Mobility.
Mobility Atlas is a web application that gives the opportunity to the common user and data analyst the ability to visually explore and interact with mobility data with the end goal of acquiring knowledge and discovering new insights. In the pages ahead this thesis discusses all the steps taken to the development of the final framework, considering all aspects which include technological and analytical elements. Particularly, these steps include the definition of a theoretical framework which illustrates the abstract model of the data, the formalization of the analytical functions based on this model, the design and the implementation of the framework. A real life situation is taken in consideration by utilizing a large dataset of human trajectories, a GPS dataset from more than 150k vehicles in Italy. Some examples of analysis performed on the data are also provided in order to show the potential of the analytical tool. The resulting web framework is built using several technologies, such as Node.js, HTML, CSS and d3.js, the JavaScript library which is nowadays the standard for web-based data visualization projects
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