Search results for "image processing"
showing 10 items of 3285 documents
Structure of a molluscan hemocyanin didecamer (HtH1 from Haliotis tuberculata) at 12 Å resolution by cryoelectron microscopy
2000
A 12 A resolution three-dimensional density map of the Haliotis tuberculata hemocyanin type 1 (HtH1) didecamer has been obtained by cryoelectron microscopy of unstained molecules and angular reconstitution. The dyad symmetry of the 8 MDa D5 HtH1 didecamer, formed by the pairing of two asymmetric 4 MDa ring-like C5 decamers, is emphasised. The major and minor surface helical grooves of the didecamer are well defined, in agreement with earlier data on molluscan hemocyanins. The location of the obliquely orientated repeating unit, a subunit dimer, within the decamer has been defined. Following interactive extraction of this dimer, several new structural features of the dimer and of the subunit…
Comparative 11A structure of two molluscan hemocyanins from 3D cryo-electron microscopy
2006
Abstract Hemocyanins are giant extracellular proteins that transport oxygen in the hemolymph of many molluscs. Molluscan hemocyanins are cylindrical decamers or didecamers of a 350–400 kDa subunit that contains seven or eight different covalently linked globular functional units (FUs), arranged in a linear manner. Each FU carries a single copper active site and reversibly binds one dioxygen molecule. As a consequence, the decamer can carry up to 70 or 80 O 2 molecules. Although complete sequence information is now available from several molluscan hemocyanins, many details of the quaternary structure are still unclear, including the topology of the 10 subunits within the decamer. Here we sho…
Bɪ-CомDᴇт: Community Detection in Bipartite Networks
2019
Abstract Extracting hidden communities from bipartite networks witnessed a determined effort. In this respect, different streams of research relied on bipartite networks to unveil communities. In this paper, we introduce a new approach, called Bi-Comdet, that aims to an efficient community detection in bipartite networks. The main trust of the introduced approach is that it stresses on the importance of grouping two types of nodes in communities having a full connection between its nodes. The quality of the unveiled communities, is assessed through some metrics borrowed from the FCA community, to wit modularity, overlapping and stability. These metrics are then aggregated through the use of…
Ralistic visual immersion : Proposal of an evaluation model
2018
The thesis "Hyper-realistic and multi-sensorial 3D visual immersion" was carried out within the framework of a CIFRE contract established between Arts et Métiers on the one hand and Renault SAS on the other. It proposes a score model to objectively evaluate the ability of an immersive display system to reproduce the right level of sensory stimulation for a user, compared to what he would receive in reality and to the modeling of the human visual system.First, we were interested in laying the foundations of the model: it is composed of twelve criteria, equitably divided into a sum of vision indices and immersion indices. Each criterion is given, as far as possible, a score from 0 to 100. A s…
Weed detection by aerial imagery : toward weed management by UAV
2016
The agricultural framework aims to reduce pesticide use on fields. Weed management, which is highly herbicide consuming, became a great issue. In order to develop a weed management service using UAV, this PhD dissertation studies how to adapt the acquisition system (UAV + multispectral camera) developed by AIRINOV to detect weeds in row crops. The acquisition chain was modeled to assess some of its parameters (optical filters and spatial resolution) impact on weed detection quality. Orthoimages and orthorectified images were created using a multispectral camera (4 to 8 filters) with 6 mm to 6 cm spatial resolutions. Several weed location methods were specifically developed to study multispe…
Automatic Assessment of Depression Based on Visual Cues: A Systematic Review
2019
International audience; Automatic depression assessment based on visual cues is a rapidly growing research domain. The present exhaustive review of existing approaches as reported in over sixty publications during the last ten years focuses on image processing and machine learning algorithms. Visual manifestations of depression, various procedures used for data collection, and existing datasets are summarized. The review outlines methods and algorithms for visual feature extraction, dimensionality reduction, decision methods for classification and regression approaches, as well as different fusion strategies. A quantitative meta-analysis of reported results, relying on performance metrics r…
Real-Time Monocular Pose Estimation of 3D Objects Using Temporally Consistent Local Color Histograms
2017
We present a novel approach to 6DOF pose estimation and segmentation of rigid 3D objects using a single monocular RGB camera based on temporally consistent, local color histograms. We show that this approach outperforms previous methods in cases of cluttered backgrounds, heterogenous objects, and occlusions. The proposed histograms can be used as statistical object descriptors within a template matching strategy for pose recovery after temporary tracking loss e.g. caused by massive occlusion or if the object leaves the camera’s field of view. The descriptors can be trained online within a couple of seconds moving a handheld object in front of a camera. During the training stage, our approac…
Real-Time Monocular Segmentation and Pose Tracking of Multiple Objects
2016
We present a real-time system capable of segmenting multiple 3D objects and tracking their pose using a single RGB camera, based on prior shape knowledge. The proposed method uses twist-coordinates for pose parametrization and a pixel-wise second-order optimization approach which lead to major improvements in terms of tracking robustness, especially in cases of fast motion and scale changes, compared to previous region-based approaches. Our implementation runs at about 50–100 Hz on a commodity laptop when tracking a single object without relying on GPGPU computations. We compare our method to the current state of the art in various experiments involving challenging motion sequences and diff…
The Many Faces of a Translation
2000
First-order translations have recently been characterized as the maps computed by aperiodic single-valued nondeterministic finite transducers (NFTs). It is shown here that this characterization lifts to "V-translations" and "V-single-valued-NFTs", where V is an arbitrary monoid pseudovariety. More strikingly, 2-way V-machines are introduced, and the following three models are shown exactly equivalent to Eilenberg's classical notion of a bimachine when V is a group variety or when V is the variety of aperiodic monoids: V-translations, V-single-valued-NFTs and 2-way V-transducers.
Motion Analysis for Dynamic 3D Scene Reconstruction and Understanding
2017
This thesis studies the problem of dynamic scene 3D reconstruction and understanding using a calibrated 2D-3D camera setup mounted on a mobile platform via the analysis of objects' motions. For static scenes, the sought 3D map reconstruction can be obtained by registering the point cloud sequence. However, with dynamic scenes, we require a prior step of moving object elimination, which yields to the motion detection and segmentation problems. We provide solutions for the two practical scenarios, namely the known and unknown camera motion cases, respectively. When camera motion is unknown, our 3D-SSC and 3D-SMR algorithms segment the moving objects by analysing their 3D feature trajectories.…