Reconstruction of 3D scenes from pairs of uncalibrated images : creation of an interactive system for extracting 3D data points and investigation of automatic techniques for generating dense 3D data maps from pairs of uncalibrated images for remote sensing applications

Much research effort has been devoted to producing algorithms that contribute directly or indirectly to the extraction of 3D information from a wide variety of types of scenes and conditions of image capture. The research work presented in this thesis is aimed at three distinct applications in this area: interactively extracting 3D points from a pair of uncalibrated images in a flexible way; finding corresponding points automatically in high resolution images, particularly those of archaeological scenes captured from a freely moving light aircraft; and improving a correlation approach to dense disparity mapping leading to 3D surface reconstructions. The fundamental concepts required to describe the principles of stereo vision, the camera models, and the epipolar geometry described by the fundamental matrix are introduced, followed by a detailed literature review of existing methods. An interactive system for viewing a scene via a monochrome or colour anaglyph is presented which allows the user to choose the level of compromise between amount of colour and ghosting perceived by controlling colour saturation, and to choose the depth plane of interest. An improved method of extracting 3D coordinates from disparity values when there is significant error is presented. Interactive methods, while very flexible, require significant effort from the user finding and fusing corresponding points and the thesis continues by presenting several variants of existing scale invariant feature transform methods to automatically find correspondences in uncalibrated high resolution aerial images with improved speed and memory requirements. In addition, a contribution to estimating lens distortion correction by a Levenberg Marquard based method is presented; generating data strings for straight lines which are essential input for estimating lens distortion correction. The remainder of the thesis presents correlation based methods for generating dense disparity maps based on single and multiple image rectifications using sets of automatically found correspondences and demonstrates improvements obtained using the latter method. Some example views of point clouds for 3D surfaces produced from pairs of uncalibrated images using the methods presented in the thesis are included.EThOS - Electronic Theses Online ServiceAl-Baath UniversityGBUnited Kingdo

Study on the suspended particulate matter of a Mediterranean artificial lake (Sos Canales Lake) using Stable Isotope Analysis of carbon and nitrogen

Stable isotope analysis of carbon (C) and nitrogen (N) was used to study the nature and origin of the suspended particulate matter (SPM) in a small Mediterranean reservoir, Lake Sos Canales (SC). The δ13C and δ15N isotopic ratios, physical-chemical parameters, nutrients and phytoplankton were analyzed ca. monthly over a hydrological year on the vertical profile at two stations (lacustrine and riverine). SPM quantity and composition were related to the hydrological annual dynamic. In Mediterranean reservoirs, water-level fluctuation is one of the most important stressors, largely dependent on the strong seasonality of climate and water exploitation for human uses. Mediterranean reservoirs show different phases during a hydrological year, alternating empty and low water level (summer–autumn), re-filling (winter–spring) and high water (spring–summer) phases. Isotopic ratios of C and N were similar on the vertical profile and at the two stations during the low water phase, but differed during the re-filling and high water phases. Significant correlations were found between δ15N and water level, and between δ13C and temperature in the surface layer at the lacustrine station. An unusual δ13C distribution along the water column during the re-filling phase was interpreted on the basis of phytoplankton species composition, mainly due by Gymnodinium uberrimum

Assessment of harmful algal species using different approaches: the case study of the Sardinian coasts

The presence and distribution of harmful algal species were investigated along the coasts of Sardinia in the summer of 2012. Fourteen potentially noxious taxa were identified at 74 beaches. The majority of the recovered taxa were potentially toxic and/or high biomass producers. Alexandrium taylorii, Gymnodinium instriatum, and Ostreopsis cf. ovata were the most frequent and abundant taxa, although Barrufeta bravensis reached the highest density (4.4 106 cells L 1). Barrufeta bravensis, A. taylorii, and G. instriatum were responsible for intense water discoloration at two of the beaches sampled. Polymerase chain reaction (PCR) analyses supported the identification of several taxa and decisively identified B. bravensis. PCR assays increased the information available on the species distributions. The locations studied were heterogeneous in their prevailing environmental conditions and their morphodynamic profiles. Statistical analyses indicated that the distributions of harmful algal species correlated with gravel and medium-fine sand substrata. These data provide substantial knowledge on the distributions of harmful algal species on beaches, which have been poorly studied on a global scale. The apparent relationship between noxious species and grain size suggests that vegetative cells may be recruited from cyst beds in beach sediments

Comparison of biological and ecological long-term marine trends related to northern hemisphere climate in different marine ecosystems

Data from five sites of the International Long Term Ecological Research (ILTER) network in the North-Eastern Pacific, Western Arctic Ocean, Northern Baltic Sea, South-Eastern North Sea and in the Western Mediterranean Sea were analyzed by dynamic factor analysis (DFA) to trace common multi-year trends in abundance and composition of phytoplankton, benthic fauna and temperate reef fish. Multiannual trends were related to climate and environmental variables to study interactions. Two common trends in biological responses were detected, with temperature and climate indices as explanatory variables in four of the five LTER sites considered. Only one trend was observed at the fifth site, the Northern Baltic Sea, where no explanatory variables were identified. Our findings revealed quasi-synchronous biological shifts in the different marine ecosystems coincident with the 2000 climatic regime shift and provided evidence on a possible further biological shift around 2010. The observed biological modifications were coupled with abrupt or continuous increase in sea water and air temperature confirming the key-role of temperature in structuring marine communities

The Italian Long-Term Ecosystem Research (LTER-Italy) network: results, opportunities, and challenges for coastal transitional ecosystems

1 - The Long-Term Ecosystem Research (LTER) network, now a global reality, was founded on a combination of long-term ecological studies, short-term experiments, and comparisons among sites and eco-domains. 2 - The LTER-Italy network was officially established as a formal member of the LTER international network in 2006, following a wider on-going process in Europe; it currently consists of 22 sites representing the main ecosystem typologies of Italy. Four coastal transitional ecosystem sites are included in the LTER-Italy network: on the northern Peninsula, these include the Venice Lagoon and the lagoons of the Po River Delta, which are characterized by a temperate climate and the influence of tides; and in the southern sector, these include the coastal ecosystems of Sardinia and the Mar Piccolo of Taranto, which are characterized by a Mediterranean climate and the absence of sensible tides. 3 - In this paper, we present and discuss three main issues: (1) the LTER-International and LTER-Europe context, emphasising the most practical issues and activities that must be addressed for the effective organization and maintenance of LTER networks; (2) the history, structure, and perspectives of the national LTER-Italy network; and (3) the opportunities, strengths, and weaknesses related to participation of the LTER-Italy network in the study of coastal transitional ecosystems