- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Comparing sUAS Photogrammetrically-Derived Point Clouds with GNSS Measurements and Terrestrial Laser Scanning for Topographic Mapping
摘要： Interest in small unmanned aircraft systems (sUAS) for topographic mapping has significantly grown in recent years, driven in part by technological advancements that have made it possible to survey small- to medium-sized areas quickly and at low cost using sUAS aerial photography and digital photogrammetry. Although this approach can produce dense point clouds of topographic measurements, they have not been tested extensively to provide insights on accuracy levels for topographic mapping. This case study examines the accuracy of a sUAS-derived point cloud of a parking lot located at the Citizens Bank Arena (CBA) in Ontario, California, by comparing it to ground control points (GCPs) measured using global navigation satellite system (GNSS) data corrected with real-time kinematic (RTK) and to data from a terrestrial laser scanning (TLS) survey. We intentionally chose a flat surface due to the prevalence of flat scenes in sUAS mapping and the challenges they pose for accurately deriving vertical measurements. When the GNSS-RTK survey was compared to the sUAS point cloud, the residuals were found to be on average 18 mm and ?20 mm for the horizontal and vertical components. Furthermore, when the sUAS point cloud was compared to the TLS point cloud, the average difference observed in the vertical component was 2 mm with a standard deviation of 31 mm. These results indicate that sUAS imagery can produce point clouds comparable to traditional topographic mapping methods and support other studies showing that sUAS photogrammetry provides a cost-effective, safe, efficient, and accurate solution for topographic mapping.
关键词： terrestrial laser scanning (TLS),small unmanned aircraft system (sUAS),point cloud,accuracy,global navigation satellite system (GNSS),photogrammetry
更新于2025-09-19 17:13:59
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Simple automatic fluid displacement measurement by time-of-flight laser sensing technology for volume calibrator need
摘要： The measurement of ?uid displacement automatically is an urgent part to build an accurate calibrator of volume. The laser interferometer is the best accurate method, but it is not easy to be implemented. The primary standard of length quantity still refers to the speed of light in vacuum. Therefore, the application of laser to measure the ?uid displacement length by time-of-?ight technique is the simple best effort to achieve the suf?cient accurate results and minimize human error. The emitter and receiver of laser with 940 nm wavelength are implemented to solve this task. The purpose of this research is to measure automatically a small ?uid displacement by time-of-?ight laser method to ful?ll simply the accuracy need on volume calibrator. The measurement results indicated that this simple automatic method successfully achieved the accuracy of distance and displacement below 0.5% and 2%, respectively. However, the light refraction behavior on ?uid must be taken into account which can affect 0.6% of accuracy. In addition, limit shield can be applied to improve the measurement accuracy.
关键词： Volume calibrator,Measurement accuracy,Laser,Time of flight,Fluid displacement,Simple automatic
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Analysis of ARMA Solar Forecasting Models Using Ground Measurements and Satellite Images
摘要： Using parallel associative reduction, iterative re?nement, and conservative early termination detection, we show how to use tree-reduce parallelism to compute correctly rounded ?oating-point sums in Oelog NT depth. Our parallel solution shows how we can continue to exploit the scaling in transistor count to accelerate ?oating-point performance even when clock rates remain ?at. Empirical evidence suggests our iterative algorithm only requires two tree-reduce passes to converge to the accurate sum in virtually all cases. Furthermore, we develop the hardware implementation of two residue-preserving IEEE-754 double-precision ?oating-point adders on a Virtex 6 FPGA that run at the same 250 MHz pipeline speed as a standard adder. One adder creates the residue by truncation, requires only 22 percent more area than the standard adder, and allows us to support directed-rounding modes and to lower the cost of round-to-nearest modes. The second adder creates the residue while directly producing a round-to-nearest sum at 48 percent more area than a standard adder.
关键词： Floating-point arithmetic,accumulation,IEEE-754,parallel,accuracy,correct rounding,FPGA
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - High Performance Monolithic Dual-Wavelength InAs/InP Quantum Dash C-Band DFB Laser
摘要： Accurate depth estimation is still an important challenge after a decade, particularly from stereo images. The accuracy comes from a good depth level and preserved structure. For this purpose, a depth post-processing framework is proposed in this paper. The framework starts with the ‘‘Adaptive Random Walk with Restart (2015)’’ algorithm. To re?ne the depth map generated by this method, we introduced a form of median solver/?lter based on the concept of the mutual structure, which refers to the structural information in both images. This ?lter is further enhanced by a joint ?lter. Next, a transformation in image domain is introduced to remove the artifacts that cause distortion in the image. The proposed post-processing method is then compared with the top eight algorithms in the Middlebury benchmark. To explore how well this method is able to compete with more widely known techniques, a comparison is performed with Google’s new depth map estimation method. The experimental results demonstrate the accuracy and ef?ciency of the proposed post-processing method.
关键词： edge preserving,Stereo matching,accuracy,depth map
更新于2025-09-19 17:13:59
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Single‐reference coupled cluster methods for computing excitation energies in large molecules: The efficiency and accuracy of approximations
摘要： While methodological developments in the last decade made it possible to compute coupled cluster (CC) energies including excitations up to a perturbative triples correction for molecules containing several hundred atoms, a similar breakthrough has not yet been reported for excited state computations. Accurate CC methods for excited states are still expensive, although some promising candidates for an efficient and accurate excited state CC method have emerged recently. This review examines the various approximation schemes with particular emphasis on their performance for excitation energies and summarizes the best state-of-the-art results which may pave the way for a robust excited state method applicable to molecules of hundreds of atoms. Among these, special attention will be given to exploiting the techniques of similarity transformation, perturbative approximations as well as integral decomposition, local and embedding techniques within the equation of motion CC framework.
关键词： single reference,coupled cluster,efficiency,excited states,accuracy
更新于2025-09-19 17:13:59
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Evaluation of Factors, Influencing the Accuracy of the Digital Model, Obtained by Laser Scanning
摘要： Measurements in terrestrial laser scanning (TLS) are not perfect and are subject to errors caused by various factors affecting the quality of the capture process and the resulting final product. Careful consideration of all these factors and errors provides a good basis for assessing the quality of the data and the information received. The accuracy of the 3D model obtained from laser scanning is influenced by the density of the measurements and the modelling methods. 3D modelling algorithms allow accuracy to be improved, but modelling software cannot solve all the problems, and it is impossible to achieve high quality 3D modelling without taking into account the factors that affect the accuracy of the measurements. The investigation of error sources in TLS measurements is rather complicated due to the large number of influencing factors that are interconnected. In addition to angular and longitudinal measurements, most scanning systems also offer a measure of the intensity of the reflected signal. Because the TLS is a non-reflective geodetic technology, it means that the measurement results are highly dependent on the reflectivity of the materials. The energy of the reflected signal depends on the following physical factors: object material properties, surface colour of the object, surface temperature, surface humidity, illumination. From the experimental studies it has been confirmed that the illumination and humidity of the scanned surfaces have a significant impact on their reflecting ability and the density of the received point cloud. Evaluation of digital model accuracy is made with а plane approximation and comparison with control points. Areas with different point densities were created in order to analyse the accuracy of 3D model and to determine the optimum scanning density.
关键词： accuracy,illumination,humidity,terrestrial laser scanning,TLS,point cloud,3D model,reflectivity
更新于2025-09-16 10:30:52
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Reliability of Terrestrial Laser Scanner Measurement in Slope Monitoring
摘要： Dense 3D point clouds provided by terrestrial laser scanner (TLS) has demonstrated significant reliability of TLS in landslide monitoring. However, existence of errors in measurement is inevitable which eventually has decreased the quality of TLS data. To concretely measure the capability of TLS in landslide monitoring, this study has performed two epoch measurements using tacheometry (for benchmarking) and TLS (Topcon GLS-2000) at Kulim Techno City, Kedah, Malaysia. Sixteen (16) artificial targets were well-distributed on the slope to determine the accuracy of the employed TLS. Results obtained revealed that Topcon GLS-2000 provides 0.006m of accuracy. However, the presence of high incidence angles in TLS measurement has limited the capability to identify the significant displacement of the targets.
关键词： Slope Monitoring,Incidence Angles,Terrestrial Laser Scanner,Landslide Monitoring,Accuracy
更新于2025-09-16 10:30:52
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Integration of ZY3-02 Satellite Laser Altimetry Data and Stereo Images for High-Accuracy Mapping
摘要： Integration of satellite laser altimetry data and stereo images without ground control points (GCPs) is an attractive method for global mapping. In this paper, we propose a new strategy of integrating Ziyuan3-02 (ZY3-02) satellite stereo images and laser altimetry data using a rigorous sensor model (RSM) with laser ranging constraint under the synchronized and rational function model (RFM) with laser elevation constraint under the non-synchronized capture for high-accuracy mapping without GCPs. Four experimental regions in China are selected to validate the method. The results show that the ZY3-02 satellite laser altimetry data can be used to improve the elevation accuracy of stereo images to better than 3.0 m without GCPs. All of the conclusions are valuable for the development of China’s next generation of surveying and mapping satellites.
关键词： high-accuracy mapping,global mapping,satellite laser altimetry,ZY3-02 satellite,stereo images
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Computing, Electronics & Communications Engineering (iCCECE) - London, United Kingdom (2019.8.22-2019.8.23)] 2019 International Conference on Computing, Electronics & Communications Engineering (iCCECE) - Detailed Analysis of IRIS Recognition Performance
摘要： Iris recognition is a well-known biometric identification system which distinguishes authentic and imposter individuals based on the features of their irides. It employs stringent statistical analyses of the features of irides due to the fact that each person has a unique iris, just like a fingerprint. In this work, the approach adopted towards the iris recognition problem is through an exhaustive and careful analysis of the statistical properties of the iris images and the randomness of spurious noise effects. The ability to differentiate two different templates from each other improves with the increase in the number of the degrees of freedom (DOF). The DOF depends on the encoding schemes utilized and moreover, it is hypothesized that the encoding schemes used in themselves could influence the recognition performance. The CASIA (Chinese Academy of Sciences Institute of Automation) version 1 database of iris images used in this study has been modified by the addition of artificial noise in order to simulate practical real life in situ noisy iris capture environments. The classical and state-of-the-art segmentation techniques have been compared, determining whether they are superior to the others under several conditions. The 1D, 2D Gabor filters and the short window implementation were all tested. The conclusion was that the 2D Gabor Filters produce a lower equal error rate (EER), higher accuracy and decidability than by using the one-dimensional log Gabor filter. After modifying the one-dimensional log Gabor filters, a lower EER and higher accuracy was found as the noise level increased. This makes the modified 1D log Gabor Filters a better proposition in noisy conditions. The generated iris templates have a predetermined theoretical value of DOF and from the statistical analysis, an experimental value can be determined. The relation between these values can be used as a metric to compare different databases.
关键词： CASIA iris image database,decidability,equal error rate,degrees of freedom,recognition,accuracy,iris encoding,low-resolution images,CASIA-iris segmentation
更新于2025-09-16 10:30:52
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[IEEE 2019 24th Microoptics Conference (MOC) - Toyama, Japan (2019.11.17-2019.11.20)] 2019 24th Microoptics Conference (MOC) - High-Speed Electro-Optics Based on Lithium Niobate Nanophotonics
摘要： The strapdown inertial navigation system (SINS) can be installed on a shearer and used for monitoring its position. However, under the complex environment of the mechanized mining face, the strong vibration of the shearer may cause large calculation error. First, the dynamic model of a double-drum shearer is built with a force analysis, and the spectrum characteristics of linear vibration and angular vibration for the fuselage are then obtained. Second, the coning error and sculling error compensation models of SINS for the shearer are derived based on vibration characteristics. Meanwhile, according to the factor of the uncompensated model, multi-sample compensation model, and different coal and rock traits and different vibration frequencies of the fuselage, the shearer SINS error compensation property under multiple parameters is researched and analyzed in simulation. Finally, simulations indicate that the SINS error compensation model with the three-sample algorithm and four-sample algorithm can improve the calculating accuracy of the shearer SINS. The coning and sculling errors can be compensated effectively by the shearer error compensation model under many vibration conditions, such as different coal and rock traits and different frequencies of the fuselage.
关键词： error compensation,dynamic model of shearer,vibration characteristic,accuracy analysis,Strapdown inertial navigation system (SINS)
更新于2025-09-16 10:30:52