- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Pixels and 3-D Points Alignment Method for the Fusion of Camera and LiDAR Data
摘要： The fusion of light detection and ranging (LiDAR) and camera data is a promising approach to improve the environmental perception and recognition for intelligent vehicles because of the combination of depth and color information. One of the dif?culties in achieving the fusion is the accurate alignment of the 3-D points with the image pixels. Current methods of data alignment involve the steps of estimating the camera intrinsic parameters and developing a transformation matrix between the camera and LiDAR frame. The drawback of these methods is the accumulation of errors during the calculation of the camera intrinsic parameters and the transformation matrix. In order to improve the data alignment accuracy, we propose a novel algorithm that directly calculates the alignment between the 3-D points and the pixels without the need for camera parameters and calibration of the coordinate transformation matrix. We call the proposed method the pixel and 3-D point alignment (PPA) method. The alignment procedure is achieved by using the extracted corresponding points. First, we calculate a linear alignment matrix without considering the image distortion; and second, we optimize the parameters using the maximum likelihood estimation to consider the camera distortion. Simulation and experimental results indicate that the PPA method is able to align the 3-D points in LiDAR frame with the pixels in image frame with higher accuracy and increased robustness against noise in calibration process than comparable state-of-the-art methods.
关键词： intelligent vehicle,sensor fusion.,calibration,camera and light detection and ranging (LiDAR),Autonomous driving
更新于2025-09-04 15:30:14
-
[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - Light - fields of Circular Camera Arrays
摘要： The ray structure and sampling properties of different light-field representations inherently determine their use-cases. Currently prevalent linear data structures do not allow for joint processing of light-fields captured from multiple sides of a scene. In this paper, we review and highlight the differences in capturing and reconstruction between light-fields captured with linear and circular camera arrays. We also examine and improve the processing of light-fields captured with circular camera arrays with a focus on their use in reconstructing dense light-fields, by proposing a new resampling technique for circular light-fields. The proposed circular epipolar light-field structure creates a simple sinusoidal relation between the objects of the scene and their curves in the epipolar image, opening the way of efficient reconstruction of circular light-fields.
关键词： camera array,capture configuration,light-field
更新于2025-09-04 15:30:14
-
[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - A Study on the Impact of Visualization Techniques on Light Field Perception
摘要： Light Field imaging is a promising technology that allows to capture the whole set of light rays in a scene thus enabling the generation of perspective views from any position. This possibility can be exploited in several application scenarios, such as virtual and augmented reality or depth estimation. In this framework many issues arise due different aspects such as the large amount of generated data or to the need of dedicated and expensive hardware for Light Field capturing. Moreover, the Light Field carries information about the entire scene and the data that is delivered to the users largely differs from the traditional 2D and 3D media in terms of content and way of fruition. Dedicated rendering technology and devices for the Light Field are nowadays still not mature or quite expensive and the best option is to render the Light Field data on a conventional 2D screen. Consequently, there is the need for finding the best visualization technique that allows to exploit the information in the Light Field while being accepted by the viewers. In this paper we address this issue by considering six visualization options and by running experimental tests to study which is the technique preferred by the users.
关键词： Light Field,subjective quality assessment,2D rendering,visualization techniques
更新于2025-09-04 15:30:14
-
[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - On Multi-View Face Recognition Using Lytro Images
摘要： In this work, a simple and efficient approach for recognizing faces from light field images, notably from Lytro Illum camera, is proposed. The suggested method is based on light field images property of being rendered through a multi-view representation. In the preliminary analysis, feature vectors extracted from different views of the same Lytro picture are proved different enough to provide complementary information beneficial for face recognition purpose. Starting from a set of multiple views for each data, face verification problem is tackled and results are compared with those achieved with classical 2D images simulated using a single view, i.e. the central one. Two experiments are described and, in both cases, the presented method shows superior performances than standard algorithms adopted by classical imaging sensors.
关键词： Lytro camera,Multi-view,light field images,face recognition
更新于2025-09-04 15:30:14
-
The Impact of Blue Light Cystoscopy with Hexaminolevulinate (HAL) on Progression of Bladder Cancer – A New Analysis
摘要： Background: The International Bladder Cancer Group (IBCG) recently proposed a new de?nition of disease progression in non-muscle invasive bladder cancer (NMIBC), including change in T-stage, change to T2 or higher or change from low to high grade. Objective: To establish whether blue light cystoscopy with hexaminolevulinate (HAL) impacts the rate of progression and time to progression using the revised de?nition. Methods: An earlier long-term follow-up of a controlled Phase III study reported outcomes following blue light cystoscopy with HAL (255 patients) or white light (WL) cystoscopy (261 patients) in NMIBC patients. The data was re-analysed according to the new de?nition. Results: In the original analysis, after 4.5 years (median), eight HAL and 16 WL patients were deemed to have progressed (transition from NMIBC to muscle invasive bladder cancer, (T2-4)). According to the new de?nition, additional patients in both groups were found to have progressed: 31 (12.2%) HAL vs 46 (17.6%) WL (p = 0.085) with four (1.6%) HAL and 11 (4.2%) WL patients progressing from Ta to CIS. Time to progression was longer in the HAL group (p = 0.05). Conclusions: Applying the new IBCG de?nition there was a trend towards a lower rate of progression in HAL patients, particularly in those progressing from Ta to CIS. Time to progression was signi?cantly prolonged. This suggests that patients should receive blue light cystoscopy with HAL rather than WL at resection. Adoption of the new de?nition could allow more patients at risk of progression to be treated appropriately earlier.
关键词： NMIBC,blue light cystoscopy,Hexaminolevulinate,progression,bladder cancer
更新于2025-09-04 15:30:14
-
Electrical Manipulation of Electromagnetically Induced Transparency for Slow Light Purpose Based on Metal-Graphene Hybrid Metamaterial
摘要： A terahertz metamaterial is presented and numerically investigated to achieve tunable electromagnetically induced transparency (EIT) for slow light. The unit cell consists of cut-wire pairs and U-shaped ring resonators with graphene strips placed between the metal film and the SiO2/Si substrate. Through bright-dark mode coupling, the radiative resonance induced by the U-shaped ring is suppressed, and then the typical EIT effect is realized. The transparency window and the accompanied group delay can be electrically manipulated with different Fermi energy of the graphene. By analyzing the surface distribution, the underlying tuning mechanism of this hybrid metamaterial is investigated in detail. Moreover, the transparency peak decreases slightly with the increasing strip width of the graphene layer but completely vanishes as the strip width exceeds the length of the covered U-shaped ring. The influence of the critical index of graphene quality, i.e., carrier mobility on the EIT effect, is considered. The results of this study may provide valuable guidance in designing and analyzing tunable EIT structures based on a metal-graphene hybrid structure for slow light purposes.
关键词： slow light,electromagnetically induced transparency,graphene,metamaterial
更新于2025-09-04 15:30:14
-
The Absorption of the Curing Light Intensity by the Ceramic Material Used for Porcelain Veneers
摘要： Introduction: Porcelain veneers are widely used in aesthetic prosthetic restoration of teeth in the anterior region. The application of dental porcelain facilitates obtaining excellent, natural-looking results with minimum invasive preparation of the tooth tissues. From both the mechanical and the aesthetic point of view, the strength and the durability of an adhesive bond depends on the correct conditioning of the luted surfaces and the polymerization procedure resulting in a high monomer conversion rate in the cement. Aim: The aim of this study was to measure the absorption of the intensity of curing light passing through samples of feldspar ceramic of various colors and thicknesses. Materials and methods: The study used disc-shaped samples prepared from Feldspathic porcelain. The diameter of each disc was 9.0 mm and their thickness ranged from 0.8 mm to 2.1 mm. Discs were prepared in different shades. The curing light intensity was measured for polymerization device Blue phase LED lamp (Ivoclar Vivadent, Liechtenstein) at a 1200 mW/cm2 light intensity (± 10%) and a wavelength ranging from 380 to 515 nm. Light intensity was measured using power gauge FieldMax (Coherent, USA). Results: Based on the measurements performed, it can be concluded that curing light intensity transmission decreases exponentially with the increase of the ceramic layer thickness. The results obtained indicated that the increase in color intensity and the decrease in ceramic brightness result in a reduction of the curing light transmission. Conclusion: To achieve adequate polymerization of the composite material placed beneath the restoration layer, the curing time should be adjusted according to the specified parameters.
关键词： Dental cavities,Teeth discolouration,Photoinitiator,Tooth tissue,Light intensity
更新于2025-09-04 15:30:14
-
Surface scanning for 3D dose calculation in intraoperative electron radiation therapy
摘要： Dose calculations in intraoperative electron radiation therapy (IOERT) rely on the conventional assumption of water-equivalent tissues at the applicator end, which defines a flat irradiation surface. However, the shape of the irradiation surface modifies the dose distribution. Our study explores, for the first time, the use of surface scanning methods for three-dimensional dose calculation of IOERT. Two different three-dimensional scanning technologies were evaluated in a simulated IOERT scenario: a tracked conoscopic holography sensor (ConoProbe) and a structured-light three-dimensional scanner (Artec). Dose distributions obtained from computed tomography studies of the surgical field (gold standard) were compared with those calculated under the conventional assumption or from pseudo-computed tomography studies based on surfaces. In the simulated IOERT scenario, the conventional assumption led to an average gamma pass rate of 39.9% for dose values greater than 10% (two configurations, with and without blood in the surgical field). Results improved when considering surfaces in the dose calculation (88.5% for ConoProbe and 92.9% for Artec). More accurate three-dimensional dose distributions were obtained when considering surfaces in the dose calculation of the simulated surgical field. The structured-light three-dimensional scanner provided the best results in terms of dose distributions. The findings obtained in this specific experimental setup warrant further research on surface scanning in the IOERT context owing to the clinical interest of improving the documentation of the actual IOERT scenario.
关键词： Intraoperative radiotherapy,Structured-light 3D scanner,IOERT,Dose distribution,Surface scanning,Conoscopic holography
更新于2025-09-04 15:30:14
-
Semiconductor Heterojunctions for Enhanced Visible Light Photocatalytic H2 Production
摘要： Semiconductor-based heterojunctions have been shown to be effective photocatalytic materials to overcome the drawbacks of low photocatalytic efficiency that results from a high rate of electron?hole recombination and narrow photo-response range. In this paper, we report on the study of heterojunctions made from visible light active, graphitic carbon nitride, g-C3N4), and UV light active, strontium pyroniobate, Sr2Nb2O7. Heterojunctions made from a combination of g-C3N4 and nitrogen-doped Sr2Nb2O7 obtained at different temperatures were also studied to determine the effect of N doping. The photocatalytic performance was evaluated by using photocatalytic hydrogen evolution reaction (HER)from water g under visible light irradiation. It was found that the photocatalytic activities of as prepared heterojunctions are significantly higher than that of individual components under similar conditions. Heterojunction formed from g-C3N4 and N-doped Sr2Nb2O7 at 700oC (CN/SNON-700) showed better performance than heterojunction made from g-C3N4 and Sr2Nb2O7 (CN/SNO). A plausible mechanism for the heterojunction enhanced photocatalytic activity is proposed based on, relative band positions, and photoluminescence data.
关键词： graphitic carbon nitride,visible light photocatalysis,strontium pyroniobate,Semiconductor heterojunctions,hydrogen production
更新于2025-09-04 15:30:14
-
Physiological Response to Different Irradiation Regimes during Barley Seedlings Growth Followed by Drought Stress under Non-Photoinhibitory Light
摘要： Differences in physiological response of barley seedlings cultivated under low (LI, ~65 μmol m-2 s-1) and elevated irradiation (EI, ~450 μmol m-2 s-1) to upcoming drought were evaluated. After ten days of cultivation, drought stress was induced under LI by withholding water and was defined as: mild stress (MS), severe stress (SS), extreme stress (ES) and control (C, well watered). Decreased relative water content (RWC) in both LI and EI grown plants was associated with increased lipid peroxidation (TBARS) and electrolyte leakage (%EL) as well as with decreased total chlorophylls content at SS and ES. Antioxidative response to drought was, generally, indicated by higher accumulation of free proline, increased activities of catalase (CAT), guaiacol peroxidase (GPOD) and ascorbate peroxidase (APX). Even the majority of estimated physiological and biochemical parameters showed no differences between investigated light regimes before drought stress induction, the LI grown plants responded on drought by adjustment of the photosynthetic apparatus to prevent photoinhibitory oxidative damage. Photosynthesis downregulation in EI grown plants under ES was revealed due to reduced values of maximum quantum yield of photosystem II (Fv/Fm) and performance index (PIABS) showing that acclimatization to EI conditions lowered their tolerance to the following drought stress although it was applied under low irradiation (LI). Therefore, those plants had reduced capability to cope with the challenge of upcoming drought stress showing more pronounced cellular oxidative damage (SS and ES), less efficient and almost dysfunctional photosynthetic apparatus in extreme drought (ES).
关键词： antioxidative response,photosynthesis,Hordeum vulgare,light regime,drought stress,lipid peroxidation
更新于2025-09-04 15:30:14