3D Laser Imaging Research Articles

无扫描激光三维成像雷达研究进展及趋势分析

无扫描激光三维成像雷达研究进展及趋势分析

3D Fabrication: Multiphoton Direct Laser Writing and 3D Imaging of Polymeric Freestanding Architectures for Cell Colonization (Small 27/2017)

3D Fabrication: Multiphoton Direct Laser Writing and 3D Imaging of Polymeric Freestanding Architectures for Cell Colonization (Small 27/2017)

Multiphoton Direct Laser Writing and 3D Imaging of Polymeric Freestanding Architectures for Cell Colonization.

The realization of 3D architectures for the study of cell growth, proliferation, and differentiation is a task of fundamental importance for both technological and biological communities involved in the development of biomimetic cell culture environments. Here we report the fabrication of 3D freestanding scaffolds, realized by multiphoton direct laser writing and seeded with neuroblastoma cells, and their multitechnique characterization using advanced 3D fluorescence imaging approaches. The high accuracy of the fabrication process (≈200 nm) allows a much finer control of the micro- and nanoscale features compared to other 3D printing technologies based on fused deposition modeling, inkjet printing, selective laser sintering, or polyjet technology. Scanning electron microscopy (SEM) provides detailed insights about the morphology of both cells and cellular interconnections around the 3D architecture. On the other hand, the nature of the seeding in the inner core of the 3D scaffold, inaccessible by conventional SEM imaging, is unveiled by light sheet fluorescence microscopy and multiphoton confocal imaging highlighting an optimal cell colonization both around and within the 3D scaffold as well as the formation of long neuritic extensions. The results open appealing scenarios for the use of the developed 3D fabrication/3D imaging protocols in several neuroscientific contexts.

Field Monitoring of the Long Term Pavement Performance (LTPP) Warm-Mix Asphalt (WMA) Site in Oklahoma

As Warm-Mix Asphalt (WMA) moves into mainstream use, the lower WMA production temperature and injection of water in some WMA technologies have raised concerns on how it may affect short- and long-term field performance over the design life. Under the Long Term Pavement Performance (LTPP) Specific Pavement Study 10 (SPS-10) experiment initiative, the Oklahoma Department of Transportation (ODOT) constructed six testing sections with five different WMA methodologies and one HMA control section. This paper presents the application of several art-of-the-state high speed instruments to collect comprehensive array of pavement performance data for long term performance monitoring of this site. The newly developed 3D laser imaging technology is used to collect 1mm 3D surface data for the evaluation of pavement surface distress and transverse profiling for rutting. Longitudinal profiling for roughness and macro-texture for safety are acquired via a high speed inertial profiler, while pavement friction is continuously collected using a Grip Tester. Four data collection events have been performed since the construction of the site. Data collected on the WMA sections and the control HMA section are compared and evaluated for surface performance deterioration. It is demonstrated that the WMA sites using various technologies exhibit better or comparable performance relative to the conventional HMA, in terms of pavement cracking, rutting, and roughness. Aggregate properties and mixture design significantly impact the pavement macro-texture and skid resistance properties.

3D laser imaging using new photometric Gaussian range equation and Phong model reflection

This article tackles the challenging problem in creating 3D photorealistic scenes from mobile laser imaging data. The major disadvantage of this method is both its range and quality of reconstructed images. These parameters are strongly dependent among other on target materiel, size of the laser footprint and atmospheric attenuation. However, in this paper, we propose a new reformulation of the photometric Gaussian beam range equation on the basis of the Phong model reflection. The substantial contribution of this model in improving the quality of back return signals diffused from targets is confirmed. We prove that the novel model brings a capital gain in terms of the quality and maximum range of detection. This will increase significantly the resolution of reconstructed images and the accuracy of range measurement. Thus, the proposed approach appears promising for 3D active sensing for mapping and scenes modeling.

Geometric texture indicators for safety on AC pavements with 1 mm 3D laser texture data

Surface texture and friction are two primary characteristics for pavement safety evaluation. Understanding their relationship is critical to reduce potential traffic crashes especially at wet conditions. Texture data obtained from existing systems are restricted on either a small portion on pavement surface or one line-of-sight profile, and the currently used texture indicators, such as Mean Profile Depth (MPD), and Mean Texture Depth (MTD) only reveal partial aspects of texture property. With the emerging 3D laser imaging technology, acquiring full-lane 3D pavement surface data at sub-millimeter resolution and at highway speeds has been made possible via the newly developed PaveVision3D Ultra data collection system. In this study using 1mm 3D data collected from PaveVision3D Ultra, four types of texture indicators (amplitude, spacing, hybrid, and functional parameters) are calculated to represent various texture properties for pavement friction estimation. The relationships among those texture indicators and pavement friction are examined. MPD and Skewness – two height texture parameters, Texture Aspect Ratio (TAR) – a spatial parameter, and Surface Bearing Index (SBI) – a functional parameter are found to be the four most contributing parameters for pavement friction prediction. Finally a multivariate regression model is developed based on residual plot analysis methods to estimate pavement friction with the R-squared value of 0.95. This study would be beneficial in the continuous measurement and evaluation of pavement safety for project- and network-level pavement surveys.

离轴三反光纤阵列激光三维成像发射系统

离轴三反光纤阵列激光三维成像发射系统

Hydroplaning on Sloping Pavements Based on Inertial Measurement Unit (IMU) and 1mm 3D Laser Imaging Data

The hydroplaning risk would increase on sloping pavements due to the fact that the presence of longitudinal and cross slopes would decrease the wheel load of vehicles perpendicular to the pavement surface. In previous studies, the effects of pavement slope on vertical wheel load and relevant hydroplaning speed prediction are ignored. To address this potential problem, the paper presents two improved models based on the existing Gallaway and University of South Florida (USF) models. Firstly, 1mm 3D laser imaging data is continuously collected at highway speed with the 1mm 3D PaveVision3D Ultra system, and simultaneously cross slope is acquired with an Inertial Measurement Unit (IMU) system and calibrated with1mm 3D data. A 4.35 km pavement section with five horizontal curves is selected to investigate hydroplaning speed predicted from Gallawayand USF models, and the two improved models. 1mm 3D pavement surface data is used to estimate texture information for the models in lieu of traditional spot-laser based texture measurement devices. Findings show that hydroplaning speeds at pavement segments with large slopes are lower than that at pavement segments with no grades. Moreover, pavement segments with potential hydroplaning risk are identified by comparing predicted hydroplaning speeds with posted speed limit. The significance of this paper is integrating the real-time 1mm 3D texture data and IMU data into the improved models for potential hydroplaning prediction of sloping pavement in network level survey.

Laser array imaging point cloud registration based on adaptive threshold

Laser three-dimensional (3D) image is a novel non-cooperative target 3D image acquisition technology, and the improvements in detection capability and imaging accuracy of the system are critically dependent on efficient echo-signal processing technique and 3D reconstruction method. The registration process is an essential step in array 3D imaging laser point cloud data processing. Registration of point clouds is an effective method that solves the problem caused by the target self-occlusion in the laser 3D imaging system. The accurate registration result will help provide better support for subsequent applications, such as object reconstruction and target recognition. In this study, a set of thresholds in the iterative closest point (ICP) algorithm is analysed on the basis of the characteristics of the laser array 3D imaging system and is combined with the range error and visual lateral resolution of the system, which are both important parameters in the imaging system. To improve the accuracy and speed of registration, the stop threshold of the iterative algorithm and the corresponding point-distance threshold in the algorithm are established in a novel way based on the range error and visual lateral resolution of the system. This forms the foundation, based on which an adaptive threshold ICP algorithm is proposed. The principal idea of the algorithm is to improve the threshold set that has a considerable effect on the accuracy and speed of registration. At first, the characteristics of the imaging point clouds of the laser array 3D imaging system are analysed in the algorithm. Based on this analysis, the distance between the two point clouds and corresponding points with ideal registrations are estimated theoretically, according to the range error and visual lateral resolution of the system. The simulation results show that the theoretically estimated results and actual results have the same variation tendency, thus providing a theoretical basis for subsequent improvements. Next, the estimated results are added according to the iterative closest point algorithm. This implies that the registration thresholds are capable of changing and adapting under different iterations and imaging systems, thus improving the speed and accuracy of registrations. This phenomenon is not seen in other algorithms. Experiments involving laser array imaging of a point cloud and laser scanning of depth imaging data show that the algorithm is practical and effective for both imaging types of point clouds and can improve the speed and accuracy of registration notably. The effectiveness and feasibility of the proposed algorithm are thus verified. In addition, for its full consideration of the imaging system, the basic idea of the proposed algorithm can be used for designing future applications as required.

Modeling and simulations of three-dimensional laser imaging based on space-variant structure

A three-dimensional (3D) laser imaging system based on time of flight is proposed, based on the human retina structure. The system obtains 3D images with space-variant resolution, and we further establish mathematical models of the system and carried out simulative comparison between space-variant structure (SVS) and space-invariant structure (SIS). The system based on SVS produces significant improvements over traditional system based on SIS in the following aspects: (1) The system based on SVS uses less pixels than that based on SIS under the same field of view (FOV) and resolution. Therefore, this property is more suitable for uses in situations that require high speed and large volume data processing. (2) The system based on SVS has higher efficiency of utilization of photodiode array than that based on SIS. (3) 3D image based on SVS has the properties of rotation and scaling invariance. (4) The system based on SVS has higher echo power in outside ring of large photodiode array, which is more effective in detecting targets with low reflectance.

Network level pavement evaluation with 1 mm 3D survey system

The latest iteration of PaveVision3D Ultra can obtain true 1 mm resolution 3D data at full-lane coverage in all 3 directions at highway speed up to 60 mph. This paper introduces the PaveVision3D Ultra technology for rapid network level pavement survey on approximately 1280 center miles of Oklahoma interstate highways. With sophisticated automated distress analyzer (ADA) software interface, the collected 1 mm 3D data provide Oklahoma Department of Transportation (ODOT) with comprehensive solutions for automated evaluation of pavement surface including longitudinal profile for roughness, transverse profile for rutting, predicted hydroplaning speed for safety analysis, and cracking and various surface defects for distresses. The pruned exact linear time (PELT) method, an optimal partitioning algorithm, is implemented to identify change points and dynamically determine homogeneous segments so as to assist ODOT effectively using the available 1 mm 3D pavement surface condition data for decision-making. The application of 1 mm 3D laser imaging technology for network survey is unprecedented. This innovative technology allows highway agencies to access its options in using the 1 mm 3D system for its design and management purposes, particularly to meet the data needs for pavement management system (PMS), pavement ME design and highway performance monitoring system (HPMS).

Stabilization of PE/PEO Cocontinuous Blends by Interfacial Nanoclays

Organomodified clays are known to be effective in polymer blend compatibilization if located preferentially at the domain interfaces, but little is known regarding the origin of their localization. In this study, we investigate the effect of organomodifier, clay loading, and shear environment on the compatibilization extent in nonreactive polyethylene (LDPE)/poly(ethylene oxide) (PEO) and reactive maleic anhydride functional polyethylene (PE-g-MA)/PEO polymer blends. We pose important questions: If clay is to compatibilize blends by interfacial localization, how does organomodifier affect its localization? How does an increase in clay loading affect the shape and elasticity of the interface? What is the shear intensity needed to overcome the equilibrium distribution of clays and delaminate it from the interface? We utilize laser scanning confocal microscopy and 3D image analysis to calculate characteristic phase size and gain unique insights into the connection between the clay loading and the interfacial...

Assessment of Rut Depth Measurement Accuracy of Point-Based Rut Bar Systems Using Emerging 3D Line Laser Imaging Technology

Point-based rut bar systems are commonly used by transportation agencies. However, potential measurement errors exist in these systems because of the limited number of sample points (e.g. 3 to 31 points). Now, advanced sensing technology can acquire high-resolution transverse profiles of more than 4,000 points using 3D line laser imaging technology (termed the 3D line laser hereafter). This study, sponsored by the United States Department of Transportation (USDOT) Research and Innovative Technology Administration (RITA) program, is a) to explore the feasibility of using the 3D line laser to accurately and reliably measure rut depth, and b) to quantify the potential rut depth measurement errors using point-based rut bar systems. The rut depth measurement accuracy and repeatability of the 3D line laser were validated in laboratory and field tests. Results show that the absolute rut-depth measurement error is less than 3 mm, and, therefore, the transverse profiles acquired by the 3D line laser can be used to quantitatively evaluate the accuracy and reliability of point-based rut bar systems. Rut bar systems having 3 to 31 sensors were simulated using transverse profiles acquired by the 3D line laser. Test results show that the relative rut-depth measurement error generally decreases with the increasing number of laser sensors. However, the trend is unclear for rut bar systems with fewer sensors because the rut shape affects the rut depth measurement error more than the number of sensors. Thus, a 3-point rut bar system could outperform a 5-point system occasionally. Test results also show that the commonly used 3-point and 5-point rut bar systems can underestimate rut depth by 16% to 51% and 22% to 64%, respectively. The relative rut-depth measurement error is less than 10% only when the number of sensors is greater than 29.

Focus on lasers and imaging

Focus on lasers and imaging

3D Laser Imaging Reconstruction of Scenes Using New Photometric Gaussian Beam Range Equation

In this article the problem of three-dimensional (3-D) reconstruction of scenes from terrestrial laser rangefinder data is processed, we present the simulations results of radiometric range function of the laser range finder imaging system for better optimization of maximum range detection with a given SNR (Signal-to-noise ratio). The study proposes a new reformulation of the radiometric Gaussian beam range equation on the basis of the photodetector active area. The adjustment of the optical and geometrical characteristics of the laser range finder so defined can be used to minimize the signal span to avoid the saturation of the detector cell and improve the ranging measurements (accuracy and range) for a 3D imaging application.

8×8 APD阵列激光三维成像接收机研制

In order to realize scannerless three dimensional( 3D) laser imaging and analyze system parameters impact on ranging precision,a 3D imaging receiver with 8 × 8 elements is implemented. The receiver utilizes linear mode APD array. Analog signal amplification and threshold processing is applied to convert the optical signal to digital pulse. Then a 64 channel time to digital convertor array is implemented in FPGA,and 3D laser imaging receiver is invented which can acquire 3D information of target in real-time. First the principle of3 D imaging and construction of the receiver is introduced,including procedure and implementation of the array signal processing. Then electrical test and 3D imaging experiment are carried out for FPGA timing unit and receiver respectively,which indicate a timing resolution of 140 ps and range resolution of 0. 2 m. At last,range resolution error is analyzed and we come to the conclusion that laser pulse energy fluctuation is the main error source.

Three-dimensional imaging reconstruction algorithm of gated-viewing laser imaging with compressive sensing.

Three-dimensional (3D) laser imaging combining compressive sensing (CS) has an advantage in lower power consumption and less imaging sensors; however, it brings enormous stress to subsequent calculation devices. In this paper we proposed a fast 3D imaging reconstruction algorithm to deal with time-slice images sampled by single-pixel detectors. The algorithm implements 3D imaging reconstruction before CS recovery, thus it saves plenty of runtime of CS recovery. Several experiments are conducted to verify the performance of the algorithm. Simulation results demonstrated that the proposed algorithm has better performance in terms of efficiency compared to an existing algorithm.

3D photon counting imaging at 1550 nm with 1.5-GHz sine-wave-gated InGaAs/InP GAPD

We demonstrated a 3D laser imaging system at 1550nm with a 1.5-GHz sine-wave gated Geiger-mode InGaAs/InP avalanche photodiode (APD). An optical fiber bundle with 100 individual fiber outputs was implemented at the focal plane of the telescope, providing a 2.5-mrad imaging view. The system used single-pixel near-infrared single-photon detector to measure photons at fiber outputs instead of a photon counting array. The 1.5-GHz gated Geiger-mode InGaAs/InP APD with a timing jitter of 290ps was operated in quasi-continuous mode with detection efficiency of ∼4.3%. We achieved higher than 6-cm surface-to-surface resolution at single-photon level, showing a potential of low-energy and eye-safe laser imaging system for long-distance measurements.

Active imaging systems to see through adverse conditions: Light-scattering based models and experimental validation

Onera, the French aerospace lab, develops and models active imaging systems to understand the relevant physical phenomena affecting these systems performance. As a consequence, efforts have been done on the propagation of a pulse through the atmosphere and on target geometries and surface properties. These imaging systems must operate at night in all ambient illumination and weather conditions in order to perform strategic surveillance for various worldwide operations. We have implemented codes for 2D and 3D laser imaging systems. As we aim to image a scene in the presence of rain, snow, fog or haze, we introduce such light-scattering effects in our numerical models and compare simulated images with measurements provided by commercial laser scanners.

The Pavement Laser 3D Data Denoising Algorithm Based on the Morphology

According to the request for 3D pavement surface precise reconstruction and feature extraction as well as detection of pavement diseases, 3D data denoising algorithm was put forward for data collected by 3D laser imaging system. The main sources of 3D laser imaging system noise were analyzed. The algorithm based on biphase standard deviation filtering method and composite structural elements of the cascaded morphology filtering method is proposed, considering noise characteristics of pavement 3D data including the discontinuity and zero noise, which is combined with digital image processing technology. Denoising effect was analyzed from three aspects including the whole data, rows and columns. Experimental result shows that the denoising method can achieve good denoising effect in the total noise, rows noise and columns noise.