In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation o...In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation of CCD pixels was analyzed,and its expression was given.Then,based on the discrete expression of deformation fringes obtained after sampling,its Fourier spectrum expression was derived,resulting in an infinitely repeated"spectra island"in the frequency domain.Finally,on the basis of using a low-pass filter to remove high-order harmonic components and retaining only one fundamental frequency component,the inverse Fourier transform was used to reconstruct the signal strength.A method of reducing the sampling interval,i.e.,reducing the number of sampling points per fringe,was proposed to increase the ratio between the sampling frequency and the fundamental frequency of the grating.This was done to reconstruct the object’s surface shape more accurately under the condition of m>4.The basic principle was verified through simulation and experiment.In the simulation,the sampling intervals were 8 pixels,4 pixels,2 pixels,and 1 pixel,the maximum absolute error values obtained in the last three situations were 88.80%,38.38%,and 31.50%in the first situation,respectively,and the corresponding average absolute error values are 71.84%,43.27%,and 32.26%.It is demonstrated that the smaller the sampling interval,the better the recovery effect.Taking the same four sampling intervals in the experiment as in the simulation can also lead to the same conclusions.The simulated and experimental results show that reducing the sampling interval can improve the accuracy of object surface shape measurement and achieve better reconstruction results.展开更多
目的为成都地区正常青年汉族人群上唇相关指标三维测量数据库的建立进行先期调查,并建立参考数值。方法采用随机数字表抽样法纳入2012年9月至2019年12月于四川省人民医院就诊的志愿者。分别收集其面部多层螺旋CT(MSCT)资料,获取影像数...目的为成都地区正常青年汉族人群上唇相关指标三维测量数据库的建立进行先期调查,并建立参考数值。方法采用随机数字表抽样法纳入2012年9月至2019年12月于四川省人民医院就诊的志愿者。分别收集其面部多层螺旋CT(MSCT)资料,获取影像数据生成三维模型,并使用3-matic Medical 13.0软件进行分析,对上唇相关线性指标[人中切迹点-唇珠最低点(Ls-Sto)、唇珠最低点-下唇红唇缘中点(Sto-Li)、鼻唇点-唇珠最低点(Sn-Sto)、鼻唇点-人中切迹点(Sn-Ls)、人中切迹点-下唇红唇缘中点(Ls-Li)、右侧唇峰点-左侧唇峰点(CphR-CphL)、右侧口角点-左侧口角点(ChR-ChL)、右侧人中嵴中点-左侧人中嵴中点(MphR-MphL)、右侧鼻翼基底点-左侧鼻翼基底点(SbalR-SbalL)、唇珠最低点-颏唇沟点(Sto-Sl)]、比例指标[人中切迹点-唇珠最低点/唇珠最低点-下唇红唇缘中点(Ls-Sto/Sto-Li)、右侧人中嵴中点-左侧人中嵴中点/右侧口角点-左侧口角点(MphR-MphL/ChR-ChL)、右侧人中嵴中点-左侧人中嵴中点/右侧唇峰点-左侧唇峰点(MphR-MphL/CphR-CphL)、人中切迹点-唇珠最低点/鼻唇点-唇珠最低点(Ls-Sto/Sn-Sto)、唇珠最低点-下唇红唇缘中点/唇珠最低点-颏唇沟点(Sto-Li/Sto-Sl)],以及鼻唇角角度进行测量,并采用唇珠—双侧口角三点拟合圆法对上唇弧度进行测量,包括右侧口角点-人中切迹点-左侧口角点(ChR-Ls-ChL)、右侧人中嵴中点-鼻唇点人中切迹点中点-左侧人中嵴中点(MphR-A-MphL)、右侧鼻翼基底点-鼻唇点-左侧鼻翼基底点(SbalR-Sn-SbalL)。采用t检验比较不同性别、年龄(18~24、25~30岁)上述指标的差异,对于不同弧度位置指标的比较采用方差分析及SNK-q法进行分析。结果本研究共纳入150名志愿者,其中男性68名(45.3%),女性82名(54.7%),年龄为18~30岁,平均24岁。(1)不同性别之间比较:线性指标中Ls-Sto、Sto-Li、Sn-Sto、Sn-Ls、Ls-Li、CphR-CphL、ChR-ChL、SbalR展开更多
文摘In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation of CCD pixels was analyzed,and its expression was given.Then,based on the discrete expression of deformation fringes obtained after sampling,its Fourier spectrum expression was derived,resulting in an infinitely repeated"spectra island"in the frequency domain.Finally,on the basis of using a low-pass filter to remove high-order harmonic components and retaining only one fundamental frequency component,the inverse Fourier transform was used to reconstruct the signal strength.A method of reducing the sampling interval,i.e.,reducing the number of sampling points per fringe,was proposed to increase the ratio between the sampling frequency and the fundamental frequency of the grating.This was done to reconstruct the object’s surface shape more accurately under the condition of m>4.The basic principle was verified through simulation and experiment.In the simulation,the sampling intervals were 8 pixels,4 pixels,2 pixels,and 1 pixel,the maximum absolute error values obtained in the last three situations were 88.80%,38.38%,and 31.50%in the first situation,respectively,and the corresponding average absolute error values are 71.84%,43.27%,and 32.26%.It is demonstrated that the smaller the sampling interval,the better the recovery effect.Taking the same four sampling intervals in the experiment as in the simulation can also lead to the same conclusions.The simulated and experimental results show that reducing the sampling interval can improve the accuracy of object surface shape measurement and achieve better reconstruction results.
文摘目的为成都地区正常青年汉族人群上唇相关指标三维测量数据库的建立进行先期调查,并建立参考数值。方法采用随机数字表抽样法纳入2012年9月至2019年12月于四川省人民医院就诊的志愿者。分别收集其面部多层螺旋CT(MSCT)资料,获取影像数据生成三维模型,并使用3-matic Medical 13.0软件进行分析,对上唇相关线性指标[人中切迹点-唇珠最低点(Ls-Sto)、唇珠最低点-下唇红唇缘中点(Sto-Li)、鼻唇点-唇珠最低点(Sn-Sto)、鼻唇点-人中切迹点(Sn-Ls)、人中切迹点-下唇红唇缘中点(Ls-Li)、右侧唇峰点-左侧唇峰点(CphR-CphL)、右侧口角点-左侧口角点(ChR-ChL)、右侧人中嵴中点-左侧人中嵴中点(MphR-MphL)、右侧鼻翼基底点-左侧鼻翼基底点(SbalR-SbalL)、唇珠最低点-颏唇沟点(Sto-Sl)]、比例指标[人中切迹点-唇珠最低点/唇珠最低点-下唇红唇缘中点(Ls-Sto/Sto-Li)、右侧人中嵴中点-左侧人中嵴中点/右侧口角点-左侧口角点(MphR-MphL/ChR-ChL)、右侧人中嵴中点-左侧人中嵴中点/右侧唇峰点-左侧唇峰点(MphR-MphL/CphR-CphL)、人中切迹点-唇珠最低点/鼻唇点-唇珠最低点(Ls-Sto/Sn-Sto)、唇珠最低点-下唇红唇缘中点/唇珠最低点-颏唇沟点(Sto-Li/Sto-Sl)],以及鼻唇角角度进行测量,并采用唇珠—双侧口角三点拟合圆法对上唇弧度进行测量,包括右侧口角点-人中切迹点-左侧口角点(ChR-Ls-ChL)、右侧人中嵴中点-鼻唇点人中切迹点中点-左侧人中嵴中点(MphR-A-MphL)、右侧鼻翼基底点-鼻唇点-左侧鼻翼基底点(SbalR-Sn-SbalL)。采用t检验比较不同性别、年龄(18~24、25~30岁)上述指标的差异,对于不同弧度位置指标的比较采用方差分析及SNK-q法进行分析。结果本研究共纳入150名志愿者,其中男性68名(45.3%),女性82名(54.7%),年龄为18~30岁,平均24岁。(1)不同性别之间比较:线性指标中Ls-Sto、Sto-Li、Sn-Sto、Sn-Ls、Ls-Li、CphR-CphL、ChR-ChL、SbalR
