Search

10 pages, 4 figures, supplemental material https://royalsocietypublishing.org/doi/suppl/10.1098/rspb.2021.2384.-- Data accessibility: All data and code supporting the results are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.18931zczk, Understanding the resilience of temperate reefs to climate change requires exploring the recovery capacity of their habitat-forming species from recurrent marine heatwaves (MHWs). Here, we show that, in a Mediterranean highly enforced marine protected area established more than 40 years ago, habitat-forming octocoral populations that were first affected by a severe MHW in 2003 have not recovered after 15 years. Contrarily, they have followed collapse trajectories that have brought them to the brink of local ecological extinction. Since 2003, impacted populations of the red gorgonian Paramuricea clavata (Risso, 1826) and the red coral Corallium rubrum (Linnaeus, 1758) have followed different trends in terms of size structure, but a similar progressive reduction in density and biomass. Concurrently, recurrent MHWs were observed in the area during the 2003–2018 study period, which may have hindered populations recovery. The studied octocorals play a unique habitat-forming role in the coralligenous assemblages (i.e. reefs endemic to the Mediterranean Sea home to approximately 10% of its species). Therefore, our results underpin the great risk that recurrent MHWs pose for the long-term integrity and functioning of these emblematic temperate reefs, We acknowledge the ‘Severo Ochoa Centre of Excellence’ (CEX2019–000928-S) funding, the MCIU/AEI/FEDER [HEATMED; RTI2018-095346-B-I00], Interreg-Med Programme (5216 | 5MED18_3.2_M23_007 and 1MED15_3.2_M2_337), Foundation Prince Albert II Monaco [MIMOSA], the TOTAL-Foundation [Perfect] and the European Union's Horizon 2020 research and innovation programme (grant nos. 689518 and SEP-210597628). D.G.-G. is supported by a FPU15/05457 grant. C.L. acknowledges the support of ICREA. J.B.L is supported by the strategic Funding [UIDB/04423/2020 and UIDP/04423/2020]. N.T. received funding by the French National Research Agency-Make Our Planet Great Again [4Oceans-MOPGA and ANR-17-MPGA-0001]. D.K.K. is supported by a IJCI-2017-31457. D.G.-G., C.L., J.B.L., E.C., P.L.-S., D.K.K. and J.G. are part of the Medrecover group [2017 SGR 1521]

International audience; This article proposes an innovative approach fully based on logic to determine the relative positions and orientations of objects in a scene photographed from different points of view as well as those of the cameras used to take the pictures. The proposal is absolutely not based on 2D feature extraction, projective geometry or least squares adjustment but on a logical approach based on an enumeration of simple relationships between the objects visible in the photos. It is an approach imitating a natural and unconscious reasoning that each of us makes by observing a scene: is this object more to the right than this one? And is this other one further away from me than the one who's partially hiding it from me? It is therefore a question of approaching the problem by identifying and recognizing objects in photographs and not by measuring millions of points in space without having any idea of the object to which they belong. This article presents a "proof of concept" based on virtual experimentation: in a discrete 3D space, a simple scene, composed of spheres of different colors and cameras, is modelled in a 3D format. In this work the positioning of the spheres and cameras is limited to a plane. Cameras are placed in the scene in order to see the spheres and then for each camera an image is generated. The application reads each image and deducts relationships between object and camera. These relationships based on the visible occlusions between the projections of the objects onto the photographs, are formalized according to Allen's relationships. A knowledge base is implemented to allow an iterative process of SPARQL queries for qualitative spatial reasoning leading to a set of possible solutions. Finally, the system deduces the relative positions between objects and cameras and the result is imported and can be used within several photogrammetry software suites.

International audience; Abstract. Although fully autonomous mapping methods are becoming more and more common and reliable, still the human operator is regularly employed in many 3D surveying missions. In a number of underwater applications, divers or pilots of remotely operated vehicles (ROVs) are still considered irreplaceable, and tools for real-time visualization of the mapped scene are essential to support and maximize the navigation and surveying efforts. For underwater exploration, image mosaicing has proved to be a valid and effective approach to visualize large mapped areas, often employed in conjunction with autonomous underwater vehicles (AUVs) and ROVs. In this work, we propose the use of a modified image mosaicing algorithm that coupled with image-based real-time navigation and mapping algorithms provides two visual navigation aids. The first is a classic image mosaic, where the recorded and processed images are incrementally added, named 2D sequential image mosaicing (2DSIM). The second one geometrically transform the images so that they are projected as planar point clouds in the 3D space providing an incremental point cloud mosaicing, named 3D sequential image plane projection (3DSIP). In the paper, the implemented procedure is detailed, and experiments in different underwater scenarios presented and discussed. Technical considerations about computational efforts, frame rate capabilities and scalability to different and more compact architectures (i.e. embedded systems) is also provided.

1st Iberian Ecological Society Meeting (2019); XIV Congreso Nacional de la Asociación Española de Ecología Terrestre (AEET), Ecology: an integrative science in the Anthropocene, 4-7 February 2019, Barcelona, Spain, Characterizing the eco-evolutionary processes underlying population dynamics is a crucial task for evolutionary ecologists because of its conservation implications. The study of fine-scale spatial genetic structure (SGS), the nonrandom spatial distribution of genotypes within a population, is particularly relevant in this context because it allows inferring the interaction among demographic and evolutionary processes acting within populations. Corallium rubrum, is a habitat-forming precious octocoral from the coralligenous, one of the most diverse but also most threatened Mediterranean habitats. This long-lived species, showing low population dynamics and restricted dispersal capacity, is affected by overfishing (for its use in jewelry) and warming-induced mortality events. While these two pressures lead to dramatic shifts in population demographic structure, little is known regarding their impact on red coral population dynamics. Here, we combined population genetics (14 microsatellites), demographic surveys and photogrammetric methods to further our understanding of red coral population dynamics and to test how it may be impacted by population decline. First, focusing on a pristine-like population, we showed a decrease of SGS from recruits to adults as expected when recruits thin. Then, we compared the patterns of SGS in three populations with contrasted conservation status to characterize the interaction among demographic structure and eco-evolutionary processes (effective dispersal and genetic drift). We showed that demographic erosion induced a simplification of the network of relationships among colonies impacting the underlying processes. This study sheds new light on the dynamics of the red coral with implications for the restoration of similar species

International audience; This paper provides details of hardware and software conception and realization of a stereo embedded system for underwater imaging. The system provides several functions that facilitate underwater surveys and run smoothly in real-time. A first post-image acquisition module provides direct visual feedback on the quality of the taken images which helps appropriate actions to be taken regarding movement speed and lighting conditions. Our main contribution is a light visual odometry method adapted to the underwater context. The proposed method uses the captured stereo image stream to provide real-time navigation and a site coverage map which is necessary to conduct a complete underwater survey. The visual odometry uses a stochastic pose representation and semi-global optimization approach to handle large sites and provides long-term autonomy, whereas a novel stereo matching approach adapted to underwater imaging and system attached lighting allows fast processing and suitability to low computational resource systems. The system is tested in a real context and shows its robustness and promising future potential.

Cultural heritage (CH) resources are very diverse, heterogeneous , discontinuous and subject to possible updates and revisions in nature. The use of semantic web technologies associated with 3D graphical tools is proposed to improve the access, the exploration, the mining and the enrichment of this CH data in a standardized and more structured form. This paper presents a new ontology-based tool that allows to visualize spatial clustering over 3D distribution of CH artifacts. The data that we are processing consists of the archaeological shipwreck "Xlendi, Malta", which was collected by photogrammtry and modeled by the Arpenteur ontology. Following semantic web best practices, the produced CH dataset was published as linked open data (LOD)., peer-reviewed

UID/HIS/04209/2013 Cultural heritage (CH) resources are very diverse, heterogeneous, discontinuous and subject to possible updates and revisions in nature. The use of semantic web technologies associated with 3D graphical tools is proposed to improve the access, the exploration, the mining and the enrichment of this CH data in a standardized and more structured form. This paper presents a new ontology-based tool that allows to visualize spatial clustering over 3D distribution of CH artifacts. The data that we are processing consists of the archaeological shipwreck ”Xlendi, Malta”, which was collected by photogrammtry and modeled by the Arpenteur ontology. Following semantic web best practices, the produced CH dataset was published as linked open data (LOD). publishersversion published

International Conference on Ecological Sciences (sfecologie 2016), 24-28 October 2016, Marseille.-- 1 page, Understanding how different disturbances and protection levels shape demography and the long-term viability of structural species is a challenge in marine conservation. In this study, we focus on the long-lived Mediterranean red coral Corallium rubrum as a model species. Due to the high value of its carbonate skeleton for the ornamental industry, C. rubrum has been intensively harvested for millennia. Nowadays, most of its populations at shallow depths remain functionally impaired and warming represents a new threat to the viability of this species. We used long-term photographic series over nine C. rubrum populations located in the NW Mediterranean Sea subjected to different disturbance levels to develop population projection models to address two questions: (I) What are the demographic processes underlying the extreme life-history strategy of C. rubrum; (II) Are marine protected areas (MPAs) an effective tool to preserve the long-term viability and functional dynamics of C. rubrum populations? The results were complemented with an extensive literature review of demographic studies of marine sessile species to understand the evolution of extreme longevities. The precious C. rubrum was at the slow extreme of the fast-slow continuum of marine sessile species, given its high survival and low reproduction success. Due to high survival of C. rubrum colonies, marine protected areas did not affect C. rubrum population's extinction risk. However, protection decreased partial mortality rates and enhanced the functional dynamics of C. rubrum populations. Our results provide important insights into the management implications for marine invertebrates with extreme life-history strategies

National audience; The registration of two 3D point clouds is an essential step in many applications. The objective of our work is to estimate the isometric transformation to merge two heterogeneous point clouds obtained from two different sensors. In this paper, we present a new approach for 3D - 3D registration which is distinguished by the nature of the extracted signature on each point and by the similarity criterion used to measure the degree of similarity. The descriptor that we propose is invariant to the rotation and also to the translation and overcomes the problem of multi - resolution that is related to heterogeneous data. At the end, our approach has been tested on synthetic data and applied on heterogeneou s real data.; Le recalage de deux nuages de points 3D est une étape essentielle dans de nombreuses applications. L’objectif de notre travail est d’estimer une transformation isométrique permettant de fusionner au mieux deux ensembles hétérogènes de points issus de deux capteurs différents. Dans cet article, nous présenterons une méthode de recalage 3D - 3D originale qui se distingue par la nature de la signature extraite en chaque point et par le critère de similarité utilisé pour mesurer le degré de ressemblance. Le descripteur que nous pr oposons est invariant à la rotation et à la translation et permet également de s’affranchir du problème de la multi - résolution relatif aux données hétérogènes. Dans le but de valider notre approche, nous l’avons testé sur des données synthétiques et nous l’avons appliqué sur des données réelles hétérogènes.