Boat Extraction in Harbours From High Resolution Satellite Images Using Marked Point Processes

International audienc

Estimation of the Weight Parameter with SAEM for Marked Point Processes Applied to Object Detection

International audienceWe consider the problem of estimating one of the parameters of a marked point process, namely the tradeoff parameter between the data and prior energy terms defining the probability density of the process. In previous work, the Stochastic Expectation-Maximization (SEM) algorithm was used. However, SEM is well known for having bad convergence properties, which might also slow down the estimation time. Therefore, in this work, we consider an alternative to SEM: the Stochastic Approximation EM algorithm, which makes an efficient use of all the data simulated. We compare both approaches on high resolution satellite images where the objective is to detect boats in a harbor.Nous traitons le problème de l'estimation du paramètre d'un processus ponctuel marqué réalisant le compromis entre attache aux données et à priori, dans la définition de la densité de probabilité du processus. Dans des travaux précédants, l'algorithme d'Espérance Maximisation Stochastique (SEM) était utilisé. Cependant, SEM est connu pour avoir de mauvaises propriétés de convergence, ce qui peut également allonger le temps de calcul. C'est pourquoi nous considérons ici une alternative à SEM : l'algorithme EM avec Approximation Stochastique (SAEM), qui fait bon usage de l'ensemble des données simulées. Nous comparons les deux approches sur des images satellitaires de haute résolution où l'objectif est de détecter des bateaux dans des ports

Saavutettavuus mahdollisuuksien määrittäjänä : tapaustutkimus Perun Amazonilta

Accessibility is a crucial factor for interaction between areas in economic, cultural, political and environmental terms. Therefore, information concerning accessibility is relevant for informed decision making, planning and research. The Loreto region in the Peruvian Amazonia provides an interesting scene for an accessibility study. Loreto is sparsely populated and because there are few roads in the region, in practice all movement and transportation happens along the river network. Due to the proximity of the Andes, river dynamics are strong and annual changes in water level combined with these dynamic processes constantly reshape accessibility patterns of the region. Selling non-timber forest products (NTFP) and agricultural products (AP) in regional centres is an important income source for local rain forest dwellers. Thus, accessibility to the centres is crucial for the livelihood of local population. In this thesis I studied how accessible the regional centre Iquitos is from other parts of Loreto. In addition, I studied the regional NTFP/AP trade patterns and compared them with patterns of accessibility. Based on GPS-measurements, using GIS, I created a time-distance surface covering Loreto. This surface describes the time-distance to Iquitos, along the river network. Based on interview material, I assessed annual changes to accessibility patterns in the region. The most common regional NTFP/AP were classified according to the amount of time they can be preserved, and based on the accessibility surface, I modelled a catchment area for each of these product classes. According to my results, navigation speeds vary considerably in different parts of the river network, depending on river types, vessels, flow direction and season. Navigating downstream is, generally, faster than upstream navigation. Thus, Iquitos is better accessible from areas situated south and south west of the city, like along the rivers Ucayali and Marañon. Differences in accessibility between different seasons are also substantial: during the dry season navigation is slower due to lower water levels and emerging sand bars. Regularly operating boats follow routes only along certain rivers and close to Iquitos transport facilities are more abundant than in more distant areas. Most of the products present in Iquitos market places are agricultural products, and the share of NTFP is significantly smaller. Most of the products were classified in product class 2, and the catchment area for these products is rather small. Many products also belonged to class 5, and the catchment area for these products reaches up to the edges of my study area, following the patterns of the river network. The accessibility model created in this study predicts travel times relatively well, although in some cases the modelled time-distances are substantially shorter than observed time-distances. This is partly caused by the fact that real-life navigation routes are more complicated than the modelled routes. Rain forest dwellers having easier access to Iquitos have more opportunities in terms of the products they decide to market. Thus, they can better take advantage of other factors affecting the market potential of different products. In all, understanding spatial variation in accessibility is important. In the Amazonian context it is difficult to combine the accessibility-related needs of the local dwellers with conservation purposes and the future challenge lies in finding solution that satisfy both of these needs.Saavutettavuus on keskeinen tekijä eri alueiden välisessä vuorovaikutuksessa, olipa kyse taloudellisista, kulttuurisista, poliittisista tai ympäristöseikoista. Sen huomioiminen päätöksenteossa, suunnittelussa ja tutkimuksessa on tärkeää. Loreton maakunta Perun Amazonialla on mielenkiintoinen tutkimuskohde saavutettavuutta ajatellen. Alue on harvaanasuttua ja vaikeakulkuista; teitä on vähän, joten käytännössä kaikki liikkuminen ja kuljetukset perustuvat alueen jokiverkkoon. Andien läheisyydestä johtuen jokidynamiikka on alueella voimakasta, ja vuosittaiset tulvat sekä virtaaman vaihtelu yhdistettynä näihin dynaamisiin prosesseihin muokkaavat jatkuvasti alueen eri osien saavutettavuutta. Viljely- ja keräilytuotteiden myyminen isompien keskusten markkinoilla on yksi keskeisimmistä tulonhankkimismuodoista sademetsän asukkaille, joten keskusten saavutettavuudella on heidän elinkeinojensa kannalta tärkeä merkitys. Tässä tutkimuksessa selvitettiin, kuinka Iquitosin kaupunki on saavutettavissa muualta Loreton maakunnasta ja kuinka tämä saavutettavuus vaikuttaa viljely- ja keräiltytuotteiden kauppaan. Kenttätyöjakson aikana tehtyihin GPS-mittauksiin perustuen Loreton maakunnasta luotiin paikkatietomenetelmin aikaetäisyyspinta, joka kuvaa Iquitosin kaupungin saavutettavuutta jokiverkkoa pitkin. Saavutettavuuden vuotuista vaihtelua arvioitiin haastatteluaineiston pohjalta. Alueen tavallisimmat viljely- ja keräilytuotteet luokiteltiin niiden säilyvyyden perusteella ja kullekin tuoteluokalle mallinnettiin saavutettavuuteen pohjautuva keräilyalue. Tutkimus osoitti, että navigointinopeudet vaihtelevat huomattavasti jokiverkon eri osissa, riippuen jokityypistä, kulkuvälineestä, kulkusuunnasta ja vuodenajasta. Myötävirtaan navigointi on pääsääntöisesti nopeampaa kuin vastavirtaan navigointi, mistä johtuen Iquitos on paremmin saavutettavissa alueilta, joilta kuljetaan kaupunkiin myötävirtaan. Vuodenaikojen väliset erot saavutettavuudessa ovat myös suuret, sillä kuivana kautena navigointi on hitaampaa alhaisen vedenpinnan tason ja jokiin muodostuvien särkkien takia. Säännöllisesti liikennöivät laivat ja veneet kulkevat vain tiettyjä jokia pitkin, ja lähellä Iquitosia kuljetusmahdollisuudet ovat huomattavasti paremmat kuin kauempana keskuksesta. Suurin osa toreilla esiintyvistä tuotteista on viljelytuotteita, ja puhtaasti keräilytuotteiden osuus kaikista tuotteista on melko pieni. Suurin osa tuotteista luokiteltiin noin kolme päivää säilyviin tuotteisiin, joiden keräilyalue on hyvin suppea. Paljon tuotteita kuului myös yli viisi päivää säilyvien tuotteiden luokkaan, ja niiden keräilyalue ulottuu jokiverkkoa mukaillen monin paikoin maakunnan rajoille saakka. Saavutettavuusmalli arvioi aikaetäisyyttä suhteellisen hyvin, joskin paikoittain mallin mukaiset arvot ovat huomattavasti todellisia aikaetäisyyksiä lyhempiä. Todelliset navigointireitit ovat siis mallia monimutkaisempia. Paremman saavutettavuuden piirissä olevilla asukkailla on enemmän valinnanvaraa tuotteissa, joita he markkinoivat. Näin ollen he voivat kiinnittää enemmän huomiota muihin tekijöihin, joilla on vaikutusta tuotteiden markkinapotentiaalin. Saavutettavuuden alueellisen vaihtelun ymmärtäminen on tärkeää. Amazonialla haasteellista on yhdistää suojelunäkökulma ja paikallisten ihmisten tarpeet saavutettavuuden suhteen, ja tulevaisuuden haasteena on löytää ratkaisuja, jotka tyydyttävät molempia tarpeita

Methods for coastal monitoring and erosion risk assessment: two Portuguese case studies

Coastal zones are naturally dynamic and mobile systems exposed to natural (river flows, waves and storms) as well as human interventions that continuously reshape their morphology. Erosion phenomena related to extreme weather events and sediment scarcity are common, threatening buildings and infrastructures, as well as beaches, ecosystems and valuable wetland; conditions that pose challenges to coastal security and defence. Regular monitoring of coastal areas, assessment of their morphodynamics and identification of the processes influencing sediment transport are thus increasingly important for a better understanding of changes and evolutionary trends in coastal systems. This demands a multi-disciplinary approach involving researchers with expertise in coastal processes and state-of-the-art observation technologies. In this paper state-of-the-art surveying methods for an efficient quantification of changes in coastal environments are described and evaluated, and two NW-Portuguese case studies are presented. Survey methods included: topographic surveys based on terrestrial videogrammetric mobile mapping and aerial photogrammetry; sub-tidal bathymetry with sonar imagery using an Autonomous Surface Vehicle (ASV); as well as field observations, with sediment sampling and beach characterisation. In the first case study erosion/accretion patterns in the Douro estuary sand spit are analysed, considering its breakwater, river flow, wave and wind effects. Prior to the construction of a detached breakwater, the spitâ s morphodynamics was related to extreme river flow events, wave and wind conditions; afterwards the spit stabilized its shape and increased its area and volume. In the second case study the coast of Vila Nova de Gaia was broadly analysed, including the shoreface, foreshore and dunes, the characterization of major features and a short-period analysis of installed dynamics. Results obtained from field data, topographical surveys and numerical wave models were combined for the erosion risk assessment, using a methodology specifically developed for the study area. Both monitoring programs achieved their proposed objectives and provided valuable information to the local authorities, as gathered and processed information constitutes a valuable database for coastal planning and for ICZM purposes. They demonstrate the potential of several approaches, supported by advanced technologies, for the study of complex coastal morphodynamic processes.Zonas costeiras são sistemas naturalmente dinâmicos e móveis, expostos a fatores naturais (fluxos de rios, ondas e tempestades) e intervenções humanas, que alteram continuamente a sua morfologia. Fenómenos de erosão relacionados com temporais e escassez de sedimentos são comuns. Eles ameaçam construções e infraestruturas, praias, ecossistemas e zonas húmidas, o que constitui um desafio para a segurança e defesa costeiras. Uma monitorização regular de áreas costeiras, com avaliação da sua morfodinâmica e identificação dos processos que influenciam o transporte de sedimentos, visando uma melhor compreensão das alterações e tendências evolutivas nos sistemas costeiros, torna-se portanto cada vez mais importante. Para tal necessita-se de uma abordagem multidisciplinar e investigadores especializados em processos costeiros e tecnologias de observação de ponta. O presente trabalho descreve e avalia métodos de monitorização de última geração para uma quantificação eficiente de alterações em ambientes costeiros e apresenta dois estudos de caso Portugueses. Os métodos de observação incluem: levantamentos topográficos terrestres em modo cinemático baseados em videogrametria; levantamentos topográficos aéreos baseados em fotogrametria; batimetria sub-tidal e imagens de fundo obtidas com sonar a partir de um veículo autónomo de superfície; e observações de campo com análise de sedimentos e caracterização de praias. O primeiro caso de estudo referese à análise de padrões de erosão e acreção na restinga do estuário do Douro, tendo em conta efeitos causados pelo molhe, o caudal do rio, ondas e vento. Antes da construção de um molhe destacado, a morfodinâmica da restinga estava relacionada com eventos extremos de caudal, agitação marítima e vento. Após a construção, a forma da restinga estabilizou e observou-se um aumento da sua área e do seu volume. No segundo caso de estudo, a costa de Vila Nova de Gaia foi amplamente estudada, incluindo shoreface, foreshore e dunas, com a caracterização dos principais atributos e uma análise de curto-período da dinâmica instalada. Os resultados obtidos a partir de dados de campo, dos levantamentos topográficos e de modelos numéricos de ondas foram combinados numa análise de risco com métodos especificamente desenvolvidos para a área de estudos. Ambos os programas de monitorização atingiram os seus objetivos e geraram informação relevante para as autoridades locais. A informação recolhida e processada constitui uma base de dados valiosa para o planeamento costeiro e a Gestão Integrada de Zonas Costeiras. Os estudos demonstram o potencial das diversas abordagens, apoiadas por tecnologias avançadas, para o estudo dos processos complexos de morfodinâmica costeira.This research was partially supported by the European Regional Development Fund (ERDF) through the COMPETE – Operational Competitiveness Programme and national funds through FCT – Foundation for Science and Technology, under the project “Pest-C/ MAR/LA0015/2013”, and partially funded by the Project ECORISK (reference NORTE-07-0124-FEDER- 000054), co-financed by the North Portugal Regional Operational Programme (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF). Wave climate analyses were supported by the FCT-funded RAP project (PTDC/MAR/111223/2009)

Pushing the Boat Out: A study of spatial organisation and harbour spaces in the early Swahili ports of the Zanzibar Archipelago, 550-1100 CE

The aim of this thesis is to identify maritime activity and patterns of spatial organisation through archaeological survey at first millennium coastal settlements in the Zanzibar Archipelago, in order to explore the nature of proto-Swahili harbours and evaluate the role of maritime activity as a component of proto-Swahili settlement in the region. Despite frequent scholarly reference to the maritime cultural identity of the Swahili there has been little consideration of the maritime archaeology of first millennium East African coastal settlements. Although intertidal zones associated with later sites have been surveyed, no investigation has ever been conducted into the nature of proto-Swahili harbours. The work presents an inductive investigation of proto-Swahili harbours between the sixth and eleventh centuries in the Zanzibar Archipelago, based on observations of industrial and maritime activity in open areas along the shorelines of Swahili ports. This thesis focuses on the geophysical survey, GIS analysis, and evaluation of the maritime areas of three contemporary sites; Unguja Ukuu (c. 600-1100 CE) and Fukuchani (c. 550-800 CE) on Zanzibar, and Tumbe (c. 600-950 CE) on Pemba. The analysis demonstrates the existence of communal harbourfront activity areas hosting iron-working, crafting, and trade, and a previously unknown shoreline mosque. The comparison of the three sites indicates a pattern of maritime activity and settlement organisation in the Zanzibar Archipelago based on knowledgeable exploitation of the maritime cultural landscape. It is argued that the proto-Swahili coastal settlements of the Zanzibar Archipelago were deliberately located on beaches with shallow, sheltered harbours and convenient land-sea access in order to exploit the near-shore coastscape. Maritime activity therefore appears to have been an important component of proto-Swahili settlement from the earliest phases of permanent occupation, whilst the construction of shoreline mosques in the ninth century reflects the development of a syncretic maritime-Islamic coastal Swahili identity

“Robin Hook”: The developmental effects of Somali piracy

Copyright @ 2011 Brunel UniversityNaval counter-piracy measures off Somalia have failed to change the incentives for pirates, raising calls for land-based approaches that may involve replacing piracy as a source of income. This paper evaluates the effects of piracy on the Somali economy to establish which (domestic) groups benefit from ransom monies. Given the paucity of economic data on Somalia, we evaluate province-level market data, nightlight emissions and high resolution satellite imagery. We show that significant amounts of ransom monies are spent within Somalia. The impacts appear to be spread widely, benefiting the working poor and pastoralists and offsetting the food price shock of 2008 in the pirate provinces. Pirates appear to invest their money principally in the main cities of Garowe and Bosasso rather than in the backward coastal communities

New Global Perspectives on Archaeological Prospection

This volume is a product of the 13th International Conference on Archaeological Prospection 2019, which was hosted by the Department of Environmental Science in the Faculty of Science at the Institute of Technology Sligo. The conference is held every two years under the banner of the International Society for Archaeological Prospection and this was the first time that the conference was held in Ireland. New Global Perspectives on Archaeological Prospection draws together over 90 papers addressing archaeological prospection techniques, methodologies and case studies from 33 countries across Africa, Asia, Australasia, Europe and North America, reflecting current and global trends in archaeological prospection. At this particular ICAP meeting, specific consideration was given to the development and use of archaeological prospection in Ireland, archaeological feedback for the prospector, applications of prospection technology in the urban environment and the use of legacy data. Papers include novel research areas such as magnetometry near the equator, drone-mounted radar, microgravity assessment of tombs, marine electrical resistivity tomography, convolutional neural networks, data processing, automated interpretive workflows and modelling as well as recent improvements in remote sensing, multispectral imaging and visualisation

Coastal Erosion and Flooding Threaten Low-Lying Coastal Tracts at Lipari (Aeolian Islands, Italy)

Lipari is the largest and most populated island in the Aeolian Archipelago, a UNESCO site, and a highly frequented touristic destination. As in many other insular settings, the low-lying coastal stretches in the E and NE sectors of Lipari are locally exposed to coastal erosion and flooding, enhanced by subsidence effects leading to local sea level rise. Most of these coastal sectors appear critical, being narrow and increasingly threatened by the risk of permanent inundation and beach disappearance. In this study, this setting is placed in the wider context of the decadal evolution of the main beaches, analysed through a multidisciplinary approach, which includes remote sensing techniques (aero-photogrammetry, unmanned aerial vehicle survey, and satellite data), offshore geophysical surveys (high-resolution multibeam bathymetry), and field observations. The results show a variable interaction in space and time between natural and anthropogenic factors in the long- and mid-term evolution of the studied coastal areas. Considering that part of the local economy at Lipari depends on beach tourism, proper future management is required in the view of natural risk reduction and in the light of future climate changes and related impacts

Selected Papers from the 2018 IEEE International Workshop on Metrology for the Sea

This Special Issue is devoted to recent developments in instrumentation and measurement techniques applied to the marine field. ¶The sea is the medium that has allowed people to travel from one continent to another using vessels, even today despite the use of aircraft. It has also been acting as a great reservoir and source of food for all living beings. However, for many generations, it served as a landfill for depositing conventional and nuclear wastes, especially in its deep seabeds, and we are assisting in a race to exploit minerals and resources, different from foods, encompassed in it. Its health is a great challenge for the survival of all humanity since it is one of the most important environmental components targeted by global warming. ¶ As everyone may know, measuring is a step that generates substantial knowledge about a phenomenon or an asset, which is the basis for proposing correct solutions and making proper decisions. However, measurements in the sea environment pose unique difficulties and opportunities, which is made clear from the research results presented in this Special Issue

HERRING : An analysis of spawning ground management, ecological conditions and human impacts in Greifswald Bay, Vistula Lagoon and Hanö Bight.

This book compiles the findings of the HERRING project which was conducted from 2012 until 2015 and part-financed by the EU South Baltic Programme. The main objective of the HERRING project is to improve the consideration of including herring spawning grounds in coastal management. Herring as a resource recourse would be part of the economic development of coastal areas, and HERRING strongly emphasizes the importance of foster an integrated coastal management in the South Baltic Sea. Three case study areas in Germany, Poland and Sweden serve as the basis of the approach, which can be roughly distinguished in two parts. The analysis of the ecological parameters and conditions as well as the impacts of present and future human activities, spatial uses and natural changes The analysis and compilation of the multi-level institutions and manage- ment instruments that govern the use and protection of coastal herring spawning grounds. The management of coastal spawning areas can function as an example to show the huge diversity of interest, demands and actors that need to be considered for the sustainable use of resources and ecosystems.https://commons.wmu.se/mer_book/1002/thumbnail.jp