1,154 research outputs found
Underwater laser-based structured light system for one-shot 3D reconstruction
No full textA Laser-based Structured Light System (LbSLS) has been designed to perform underwater close-range 3D reconstructions even with high turbidity conditions and outperform conventional systems. The system uses a camera and a 532 nm green laser projector. The optical technique used is based on the projection of a pattern obtained placing a Diffractive Optical Element (DOE) in front of the laser beam. In the experiments described in this manuscript, the DOE used diffracts the laser beam in 25 parallel lines providing enough information in a single camera frame to perform a 3D reconstruction
One-shot underwater 3D reconstruction
No full textA one-shot sensor for underwater 3D reconstruction is presented and tested underwater in a water tank. The system is composed of a RGB CCD camera and a 532 nm green laser with a Diffractive Optical Element attached to it. The laser projects a pattern of parallel lines into the scene. The deformed pattern obtained in the camera frame is then processed to obtain a non-dense 3D point cloud that can be later used for autonomous manipulation and grasping, or for detailed mapping of textureless objects or scenarios
Optical Sensors and Methods for Underwater 3D Reconstruction
No full textThis paper presents a survey on optical sensors and methods for 3D reconstruction in underwater environments. The techniques to obtain range data have been listed and explained, together with the different sensor hardware that makes them possible. The literature has been reviewed, and a classification has been proposed for the existing solutions. New developments, commercial solutions and previous reviews in this topic have also been gathered and considered
Evaluation of a laser based structured light system for 3D reconstruction of underwater environments
No full textPeer Reviewe
The intellectual legacy of Miquel Batllori.
No full textThe Catalan historian Miquel Batllori (1909-2003), had developed an important performance in many aspects of intellectual activities. He developed an extensive studies in many historical subjects. The author considers mainly the Batllori works connected with cultural history.The Catalan historian Miquel Batllori (1909-2003), had developed an important performance in many aspects of intellectual activities. He developed an extensive studies in many historical subjects. The author considers mainly the Batllori works connected with cultural history
Texture analysis of seabed images: Quantifying the presence of Posidonia oceanica at Palma Bay
No full textAn automatic classifier algorithm has been designed to assess the population of Posidonia oceanica over a set of underwater images at Palma Bay. Law's energy filters and statistical descriptors of the Gray Level Co-occurrence Matrix have been use to correctly classify the input image patches in two classes: Posidonia oceanica or not Posidonia oceanica. The input images have been first preprocessed and splitted in three different patch sizes in order to find the best patch size to better classify this seagrass. From all the attributes obtained in these patches, a best subset algorithm has been run to choose the best ones and a decision tree classifier has been trained. The classifier was made by training a Logistic Model Tree from 125 pre-classified images. This classifier was finally tested on 100 new images. The classifier outputs gray level images where black color indicates Posidonia oceanica presence and white no presence. Intermediate values are obtained by overlapping the processed patches, resulting in a smoother final result. This images can be merged in an offline process to obtain density maps of this algae in the sea
Notes sobre la vida i l'obra de Miquel Joan Bodí
No full textCom a conclusió, podem dir que Miquel Joan Vimbodí va estar al servei del Cardenal Espínola, que es pot considerar un erudit interessat, sobretot, en la història, com són la major part de les seues obres, i com manifesten les seues relacions, primer amb l'historidador Juan de Mariana, amb els cronistes Tamayo de Vargas, Gil Dávila i Andrés de Ustarroz, i el que realment respectaven i en certa manera admiraven els seus amics i que el caracteritza és la pràctica de l'escriptura en llatí
Stereo-vision graph-SLAM for robust navigation of the AUV SPARUS II
No full textThis paper presents the integration of a stereo-vision Graph-SLAM system in the navigation and control architecture of the Autonomous Underwater Vehicle (AUV) SPARUS II. The navigation architecture of SPARUS II is endowed with an Extended Kalman Filter (EKF) that fuses the data provided by a Doppler Velocity Log (DVL), a pressure sensor, a GPS (when the vehicle is in the surface) and an Inertial Measurement Unit (IMU). But due to the nature of the aforementioned sensors, this localization data is prone to drift. Instead, the stereo-vision Graph-SLAM clearly improves the localization data thanks to the additional pose constraints computed from visual (stereo) loop closings. SLAM estimates are thereafter inserted in the control architecture to increase the precision in the navigation and mission tasks. Experiments with SPARUS II in simulated environments show the improvement and benefits in the application of this SLAM approach for localization, navigation and control, with respect to the use of the EKF odometry
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