Repeatable semantic reef-mapping through photogrammetry and label-augmentation

In an endeavor to study natural systems at multiple spatial and taxonomic resolutions, there is an urgent need for automated, high-throughput frameworks that can handle plethora of information. The coalescence of remote-sensing, computer-vision, and deep-learning elicits a new era in ecological research. However, in complex systems, such as marine-benthic habitats, key ecological processes still remain enigmatic due to the lack of cross-scale automated approaches (mms to kms) for community structure analysis. We address this gap by working towards scalable and comprehensive photogrammetric surveys, tackling the profound challenges of full semantic segmentation and 3D grid definition. Full semantic segmentation (where every pixel is classified) is extremely labour-intensive and difficult to achieve using manual labeling. We propose using label-augmentation, i.e., propagation of sparse manual labels, to accelerate the task of full segmentation of photomosaics. Photomosaics are synthetic images generated from a projected point-of-view of a 3D model. In the lack of navigation sensors (e.g., a diver-held camera), it is difficult to repeatably determine the slope-angle of a 3D map. We show this is especially important in complex topographical settings, prevalent in coral-reefs. Specifically, we evaluate our approach on benthic habitats, in three different environments in the challenging underwater domain. Our approach for label-augmentation shows human-level accuracy in full segmentation of photomosaics using labeling as sparse as 0.1%, evaluated on several ecological measures. Moreover, we found that grid definition using a leveler improves the consistency in community-metrics obtained due to occlusions and topology (angle and distance between objects), and that we were able to standardise the 3D transformation with two percent error in size measurements. By significantly easing the annotation process for full segmentation and standardizing the 3D grid definition we present a semantic mapping methodology enabling change-detection, which is practical, swift, and cost-effective. Our workflow enables repeatable surveys without permanent markers and specialized mapping gear, useful for research and monitoring, and our code is available online. Additionally, we release the Benthos data-set, fully manually labeled photomosaics from three oceanic environments with over 4500 segmented objects useful for research in computer-vision and marine ecology

A photomosaic image generation method using photo annotation in a social network environment

With the growing use of social networking services, various applications have been developed to utilize their vast capabilities. Photomosaic techniques, which combine many images to create a new rendering of an input image, can benefit from the capabilities of social networks. In this study, we propose a method that generates a photomosaic image by considering social network context. Our algorithm creates a photomosaic that incorporates photos posted by other users in the users network. We enable the matching function to easily select photos from the albums of users who are connected to the owner of the input image, by computing the closeness of those connections. Moreover, our technique allows the photos in the albums of friends who are annotated in the source image to be matched more effectively

Photo collage-based photograph display system on mobile computing platform

In the last few decades, mobile computing platform technology has grown rapidly, as observed from smart phones that have quickly become ubiquitous. The mobile computing platform is the most widely used platform in our life today, and digital photographs captured through these devices have become routine for most people. In this study, we propose a novel artistic method for displaying photographs in mobile devices as a photo collage. Using our system, users can view a representative photograph as a collage of photographs associated with a certain event and access each of photographs individually. To implement this, we employ centroidal Voronoi diagram to obtain an even distribution of tiles, and use the sites as the location of tiles. We use the edge avoidance technique to prevent tiles from being located across the edges. To obtain the direction of tiles that follow near a strong edge, we employ the Edge tangent Flow field and use the field as the directions of tiles. Finally, we search for photographs that best match the tiles calculated above by using a thumbnail difference metric

High spatial resolution photo mosaicking for the monitoring of coralligenous reefs

AbstractCoralligenous reefs are characterized by large bathymetric and spatial distribution, as well as heterogeneity; in shallow environments, they develop mainly on vertical and sub-vertical rocky walls. Mainly diver-based techniques are carried out to gain detailed information on such habitats. Here, we propose a non-destructive and multi-purpose photo mosaicking method to study and monitor coralligenous reefs developing on vertical walls. High-pixel resolution images using three different commercial cameras were acquired on a 10 m2 reef, to compare the effectiveness of photomosaic method to the traditional photoquadrats technique in quantifying the coralligenous assemblage. Results showed very high spatial resolution and accuracy among the photomosaic acquired with different cameras and no significant differences with photoquadrats in assessing the assemblage composition. Despite the large difference in costs of each recording apparatus, little differences emerged from the assemblage characterization: through the analysis of the three photomosaics twelve taxa/morphological categories covered 97–99% of the sampled surface. Photo mosaicking represents a low-cost method that minimizes the time spent underwater by divers and capable of providing new opportunities for further studies on shallow coralligenous reefs

Globally aligned photomosaic of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37°18.5′N) : release of georeferenced data, mosaic construction, and viewing software

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q12009, doi:10.1029/2008GC002204.We present a georeferenced photomosaic of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37°18′N). The photomosaic was generated from digital photographs acquired using the ARGO II seafloor imaging system during the 1996 LUSTRE cruise, which surveyed a ∼1 km2 zone and provided a coverage of ∼20% of the seafloor. The photomosaic has a pixel resolution of 15 mm and encloses the areas with known active hydrothermal venting. The final mosaic is generated after an optimization that includes the automatic detection of the same benthic features across different images (feature-matching), followed by a global alignment of images based on the vehicle navigation. We also provide software to construct mosaics from large sets of images for which georeferencing information exists (location, attitude, and altitude per image), to visualize them, and to extract data. Georeferencing information can be provided by the raw navigation data (collected during the survey) or result from the optimization obtained from image matching. Mosaics based solely on navigation can be readily generated by any user but the optimization and global alignment of the mosaic requires a case-by-case approach for which no universally software is available. The Lucky Strike photomosaics (optimized and navigated-only) are publicly available through the Marine Geoscience Data System (MGDS, http://www.marine-geo.org). The mosaic-generating and viewing software is available through the Computer Vision and Robotics Group Web page at the University of Girona (http://eia.udg.es/∼rafa/mosaicviewer.html).This work has been supported by the EU Marie Curie RTNs MOMARNet (OD, RG, JE, LN, JF, NG) and FREESUBNet (RG, NG, XC), the Spanish Ministry of Science and Innovation (grant CTM2007–64751; RG, JE), CNRS and ANR (grant ANR NT05–3_42212, JE), ICREA (LN), and by the Generalitat de Catalunya (JE, RG). JF has been funded by MICINN under FPI grant BES-2006-12733 and NG has been supported by MICINN under the ‘‘Ramon y Cajal’’ program

Perceptually Inspired Real-time Artistic Style Transfer for Video Stream

This study presents a real-time texture transfer method for artistic style transfer for video stream. We propose a parallel framework using a T-shaped kernel to enhance the computational performance. With regard to accelerated motion estimation, which is necessarily required for maintaining temporal coherence, we present a method using a downscaled motion field to successfully achieve high real-time performance for texture transfer of video stream. In addition, to enhance the artistic quality, we calculate the level of abstraction using visual saliency and integrate it with the texture transfer algorithm. Thus, our algorithm can stylize video with perceptual enhancements

Characterization of benthic communities at Loki’s Castle vent field using a photomosaic

Postponed access: the file will be accessible after 2022-08-30Loki’s Castle was the first black smoker hydrothermal vent field to be discovered on the Arctic Mid-Ocean Ridge (AMOR), and is known to host a specialized and highly endemic fauna. Despite being studied since its discovery in 2008 there are still knowledge gaps, especially regarding the diversity and spatial distribution of the faunal community. The increasing interest in opening areas at the AMOR to deep sea mining makes it crucial to gather baseline data from the sites that could be affected, including Loki’s Castle. The purpose of this thesis was to characterize the abundance, diversity and spatial distribution of the benthic megafauna community at Loki’s Castle and to investigate the influence of abiotic factors on this community. To achieve this, an ortophotomosaic created from seafloor images of the area was used to annotate and quantify all visible fauna. These observations were analyzed together with pre-existing data of abiotic parameters (temperature and heat flux) and topographic variables (slope, aspect and roughness) from the vent field, using a multivariate analytical framework. A total of 14743 observations were recorded, and 20 morphospecies belonging to eight different phyla were identified. There were statistically significant differences between diffuse venting areas, focused venting areas and peripheral areas in density, diversity and morphospecies distribution. The diffuse venting site called the Barite field supports a diverse and dense community of organisms. Some of these, such as the tubeworm Sclerolinum contortum, are dependent on symbiosis with chemosynthetic bacteria, while others are likely influenced by a facilitating cascade where S. contortum is the primary foundation species. Temperature and slope were found to significantly influence the spatial distribution of most of the prominent morphospecies, total abundance and species richness. However, most of the species distributions could not be explained by temperature and slope, and it is likely that other biological and abiotic factors such as food availability, competition, predation, substrate and hydrothermal fluid composition also contribute to the observed patterns. This hypothesis should be investigated in future experimental studies. A seabed mining event at or near Loki’s Castle could change the benthic megafaunal community through elimination of vital habitat and alteration of the hydrothermal circulation from vents. This thesis provides baseline knowledge that can be useful in assessing how the benthic megafaunal community will be impacted by a possible future mining event.Masteroppgave i biologiBIO399MAMN-BIOMAMN-HAVS

Architecture of coarse grained (conglomeratic) deep water lobes at the base of a sandstone dominated fan, Jurassic Los Molles Formation, Neuquén Basin, Argentina

textThe complex structural and stratigraphic framework of the Neuquén Basin developed by Triassic-Jurassic extensional processes formed a deep basin and accumulated coarse-grained gravity flow deposits on slope and basin floor. The Los Molles Formation exposes the succession of gravity flow deposits from conglomerates to mudstones over a 9 km outcrop belt in southern Neuquén Basin. The Los Molles Fm. is over 1000 meters thick and its basal part is ~200 meters thick consisting of two fan units capped by 0.5-3 m of conglomerate beds. The initial deepwater fan units start with unusual pebble- and cobble-rich conglomerate beds at their base. To characterize the conglomerate lobes and their link with the correlative and overlaying basin-floor lobe complexes, satellite images, DEM (Digital Elevation Model), photomosaics (a few km), and 19 measured sections (30-190m thick) have been collected and interpreted. In all units measured, each lobe contains, from bottom to top, very coarse, poorly sorted, and erosional-based conglomerates (1-3m) overlain by amalgamated, normal graded turbidite sandstone beds (20-30m), and silty mudstone beds (up to 15m). Each of these three facies associations forms a succession (about 30-40 m thick) of lobe complexes with an overall fining upward trend. The conglomerate thickness and lateral extent decreases upwards as the third (uppermost) conglomerate layer demonstrates rather discontinuous, lenticular bodies. In contrast, the sandstone beds increase upward in thickness with finer grain size and better sorting. The conglomerate beds are interpreted as debris flow deposits based on their structureless and poorly sorted texture. However, some conglomerates are at times erosional at the base, poorly sorted throughout, but others are capped by normal grading for up to a third of their thickness. Normal grading suggests debris flow transforming into turbidity flow vertically. Flute marks associated with sandstone and conglomerate beds indicate paleoflow toward the east, in contrast to younger sandy fans that shows progradation dominantly north-northeastwards. The modern Var River system in southern France has a similar morphology with pebbles and cobbles transported to deepwater via steep gradient slope. As in the Var system, coarse sediments in the Los Molles Fm. bypass the shelf and steep slope to build the initial base of the fan. In summary, the earliest Los Molles conglomeratic fans were linked with high relief of the basin margin. Later, this margin relief decreased, and sandstone dominated fans.Geological Science

Tree species identification on large-scale aerial photographs in a tropical rain forest, French Guiana—application for management and conservation

International audienceManagement and conservation planning of any ecosystem requires knowledge of species composition. This is a real challenge in tropical rain forests that are characterised by very high species richness and canopy access limitations. The possibility of approaching trees from remote sensing on large-scale aerial photographs, takes on its full significance in this context. Results of tree species identification by photo-interpretation in a French Guianan forest canopy are discussed, as well as an overview of the part of the forest accessible from the photographs. Two sets of aerial photographs were used. One set (1:3700 colour slides) covers 15 ha of primary forest, divided into a training set (TS, 5 ha) and a validation set (VS 1: 10 ha). Another validation set, taken in different conditions of acquisition, scale and season, is available for an adjacent area (VS 2: 6.5 ha). Aerial photographs captured a quarter of the tree community (dbh ! 10 cm) on average, and about 45% of the SGS (Species or Group of Species) on the training set. The crown appearance of 12 major canopy SGS, including commercial species and species of ecological interest, had been described in a previous work on the same training set. Following these descriptions, two photo-interpreters separately identified 309 tree crowns overall on VS 1, with a good agreement in their respective judgements. After their interpretations were checked in the field, the overall average identification success was high (87%) but the results varied according to the SGS. The results on VS 2 showed that some species displayed major seasonal and scale variations and were hardly recognized, whereas some others could be identified without modifying the learning process. The results are encouraging and this work will be extended as the identification of tropical rain forest trees from remote sensing has many applications, ranging from fundamental ecological knowledge of canopy species to the management and conservation of such highly diverse and hardly inventoried ecosystems