A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a...A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a coastal location and to characterize their properties and behaviors. Primary and secondary field observation methods were utilized in this data-centric study. Forensic engineering principles and methodologies guided the study. The challenges set forward were object detection, observation, and characterization, where multispectral electro-optical devices and radar were employed due to limited visual acuity and intermittent presentation of the phenomena. The primary means of detection utilized a 3 cm X-band radar operating in two scan geometries, the X- and Y-axis. Multispectral electro-optical devices were utilized as a secondary means of detection and identification. Data was emphasized using HF and LF detectors and spectrum analyzers incorporating EM, ultrasonic, magnetic, and RF field transducers to record spectral data in these domains. Data collection concentrated on characterizing VIS, NIR, SWIR, LWIR, UVA, UVB, UVC, and the higher energy spectral range of ionizing radiation (alpha, beta, gamma, and X-ray) recorded by Geiger-Müller counters as well as special purpose semiconductor diode sensors.展开更多
目的配准是术前影像引导的椎弓根螺钉内固定术中的重要环节。术前CT影像三维重建获得的点云和术中捕获的暴露部位点云重叠率低,易受噪声、遮挡等因素的干扰,使点云配准更具挑战性。本文采用局部特征和距离度量相结合的方式应对低重叠率...目的配准是术前影像引导的椎弓根螺钉内固定术中的重要环节。术前CT影像三维重建获得的点云和术中捕获的暴露部位点云重叠率低,易受噪声、遮挡等因素的干扰,使点云配准更具挑战性。本文采用局部特征和距离度量相结合的方式应对低重叠率配准问题。方法首先利用方向直方图描述子(signature of histograms of orientations,SHOT)和随机抽样一致算法(random sample consensus,RANSAC)提取并匹配几何特征相似的点,完成初始对齐。应用目标函数对称ICP,通过最小化对称化点到面目标函数得到最终变换矩阵。对来源于SpineWeb公开数据集的5组腰椎数据进行配准实验。结果术前术中点云配准实验中平均配准误差为0.128 mm,平均运行时间为5.750 s。结论实验结果验证了该算法在低重叠率术前术中点云配准中的有效性,使得外科医生能及时根据配准结果调整手术器械,从而提高椎弓根螺钉置入准确率。展开更多
文摘A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a coastal location and to characterize their properties and behaviors. Primary and secondary field observation methods were utilized in this data-centric study. Forensic engineering principles and methodologies guided the study. The challenges set forward were object detection, observation, and characterization, where multispectral electro-optical devices and radar were employed due to limited visual acuity and intermittent presentation of the phenomena. The primary means of detection utilized a 3 cm X-band radar operating in two scan geometries, the X- and Y-axis. Multispectral electro-optical devices were utilized as a secondary means of detection and identification. Data was emphasized using HF and LF detectors and spectrum analyzers incorporating EM, ultrasonic, magnetic, and RF field transducers to record spectral data in these domains. Data collection concentrated on characterizing VIS, NIR, SWIR, LWIR, UVA, UVB, UVC, and the higher energy spectral range of ionizing radiation (alpha, beta, gamma, and X-ray) recorded by Geiger-Müller counters as well as special purpose semiconductor diode sensors.
文摘目的配准是术前影像引导的椎弓根螺钉内固定术中的重要环节。术前CT影像三维重建获得的点云和术中捕获的暴露部位点云重叠率低,易受噪声、遮挡等因素的干扰,使点云配准更具挑战性。本文采用局部特征和距离度量相结合的方式应对低重叠率配准问题。方法首先利用方向直方图描述子(signature of histograms of orientations,SHOT)和随机抽样一致算法(random sample consensus,RANSAC)提取并匹配几何特征相似的点,完成初始对齐。应用目标函数对称ICP,通过最小化对称化点到面目标函数得到最终变换矩阵。对来源于SpineWeb公开数据集的5组腰椎数据进行配准实验。结果术前术中点云配准实验中平均配准误差为0.128 mm,平均运行时间为5.750 s。结论实验结果验证了该算法在低重叠率术前术中点云配准中的有效性,使得外科医生能及时根据配准结果调整手术器械,从而提高椎弓根螺钉置入准确率。
