Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pa...Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pattern projection.However,the imaging speed of conventional fringe projection profilometry(FPP)remains limited by the native sensor refresh rates due to the inherent"one-to-one"synchronization mechanism between pattern projection and image acquisition in standard structured light techniques.Here,we present dual-frequency angular-multiplexed fringe projection profilometry(DFAMFPP),a deep learning-enabled 3D imaging technique that achieves high-speed,high-precision,and large-depth-range absolute 3D surface measurements at speeds 16 times faster than the sensor's native frame rate.By encoding multi-timeframe 3D information into a single multiplexed image using multiple pairs of dual-frequency fringes,high-accuracy absolute phase maps are reconstructed using specially trained two-stage number-theoretical-based deep neural networks.We validate the effectiveness of DFAMFPP through dynamic scene measurements,achieving 10,000 Hz 3D imaging of a running turbofan engine prototype with only a 625 Hz camera.By overcoming the sensor hardware bottleneck,DFAMFPP significantly advances high-speed and ultra-high-speed 3D imaging,opening new avenues for exploring dynamic processes across diverse scientific disciplines.展开更多
Two- dimensional Fourier transform profilometry (2 -D FTP) for data acquisition of fabric surface shapes isproposed. Phase unwrapping technique based on digitalweighted filter and reliability mask are employed. Ex-per...Two- dimensional Fourier transform profilometry (2 -D FTP) for data acquisition of fabric surface shapes isproposed. Phase unwrapping technique based on digitalweighted filter and reliability mask are employed. Ex-perimentai results of shape measurement for several fab-ric appearances are given. From the measured results, itis shown that this method can make up for not only thedisadvantage of the gray level image analysis which isonly suitable for simple structure and solid - pattern fab-ric, but also the low speed and high cost of laser dotscanning technique.展开更多
Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a sing...Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a single fringe image.In this paper,we demonstrate that the deep neural networks can be trained to directly recover the absolute phase from a unique fringe image that involves spatially multiplexed fringe patterns of different frequencies.The extracted phase is free from spectrum-aliasing problem which is hard to avoid for traditional spatial-multiplexing methods.Experiments on both static and dynamic scenes show that the proposed approach is robust to object motion and can obtain high-quality 3D reconstructions of isolated objects within a single fringe image.展开更多
Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measure...Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector-camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method.展开更多
2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to ...2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.展开更多
The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is abl...The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is able to automatically recognize any position between depression and elevation on an object surface.Theoretical analysis and experimental verification are presented.展开更多
BACKGROUND Artificial urethral sphincter(AUS)implantation is currently the gold standard for treating moderate and severe urinary incontinence.Currently,cuffs are chosen based on the surgeon’s experience,and adjustin...BACKGROUND Artificial urethral sphincter(AUS)implantation is currently the gold standard for treating moderate and severe urinary incontinence.Currently,cuffs are chosen based on the surgeon’s experience,and adjusting cuff tightness is crucial.The TDOC air-charged catheter has not been proven to be inferior to traditional catheters.We report how intraoperative urethral pressure profilometry is performed using a T-DOC air-charged catheter with ambulatory urodynamic equipment,to guide cuff selection and adjustment.CASE SUMMARY A 67-year-old man presented to our hospital with complete urinary incontinence following transurethral prostatectomy,using five pads/d to maintain local dryness.Preoperatively,the maximum urethral pressure(MUP)and maximum urethral closure pressure(MUCP)were 52 cmH2O and 17 cmH2O,respectively.An AUS was implanted.Intraoperatively,in the inactivated state,the MUP and MUCP were 53 cmH2O and 50 cmH2O,respectively;in the activated state,they were 112 cmH2O and 109 cmH2O,respectively.The pump was activated 6 wk postoperatively.Re-measurement of the urethral pressure on the same day showed that in the inactivated state,MUP and MUCP were 89 cmH2O and 51 cmH2O,respectively,and in the activated state,120 cmH2O and 92 cmH2O,respectively.One month after device activation,telephonic follow-up revealed that pad use had decreased from five pads/d to one pad/d,which met the standard for social continence(0-1 pad per day).There were no complications.CONCLUSION The relationship between intraoperative urethral pressure and urinary continence post-surgery can provide data for standardizing AUS implantation and evaluating efficacy.展开更多
An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain ...An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one step phase shift algorithm.In comparison with traditional phase shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.展开更多
An integrated and reliable phase unwrapping algorithm is proposed based on residues and blocking-lines detection, closed contour extraction and quality map ordering for the measurement of 3D shapes by Fourier-transfor...An integrated and reliable phase unwrapping algorithm is proposed based on residues and blocking-lines detection, closed contour extraction and quality map ordering for the measurement of 3D shapes by Fourier-transform profilometry (FTP). The proposed algorithm first detects the residues on the wrapped phase image, applies wavelet analysis to generate the blocking-lines that can just connect the residues of opposite polarity, then carries out the morphology operation to extract the closed contour of the shape, and finally uses the modulation intensity information and the Laplacian of Gaussian operation of the wrapped phase image as the quality map. The unwrapping process is completed from a region of high reliability to that of low reliability and the blocking-lines can prevent the phase error propagation effectively. Furthermore, by using the extracted closed contour to exclude the invalid areas from the phase unwrapping process, the algorithm becomes more efficient. The experiment shows the effec-tiveness of the new algorithm.展开更多
In Fourier transform profilometry （FTP）, we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device （CCD） and increase the measurement accuracy of the object shape. Firstly, the ...In Fourier transform profilometry （FTP）, we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device （CCD） and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical ex- planation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.展开更多
In order to study the strength of the composite material plate problems, need to adopt a nondestructive testing method to obtain the specimen surface under the effect of high-speed impact regularity of shape. The proj...In order to study the strength of the composite material plate problems, need to adopt a nondestructive testing method to obtain the specimen surface under the effect of high-speed impact regularity of shape. The projection profilometry was used to measure the surface profile or the full field deformation. Furtherly, by using the Fourier transform algorithm, there is only one frame of captured image</span><span style="font-family:Verdana;"> which</span><span style="font-family:Verdana;"> is needed in the measurement, so that it can be introduced into the high speed impaction procedure measurement. An experimental system, which was contained with an impact setup and the projection profilometry measurement part, was constructed for the impaction action characteristic research. The metallic impact object can be launched by a gas gun or a spin fan, respectively. The detected object </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> manufactured by composite materials. In order to increase the surface deformation measurement accuracy, the calibration method and the error was discussed with different calibration specimen. And then, the proposed profilometry measurement method is proved by the gas gun and spin fan projectile test. The surface deformation of the manufactured composite plates and fan case are measured in the impaction procedure. So that the impact action details can be described much more clearly than the traditional video monitoring method.展开更多
Fringe projection profilometry(FPP)is a method that determines height by analyzing distortional fringes,which is widely used in high-accuracy 3D imaging.Now,one major reason limiting imaging speed in FPP is the projec...Fringe projection profilometry(FPP)is a method that determines height by analyzing distortional fringes,which is widely used in high-accuracy 3D imaging.Now,one major reason limiting imaging speed in FPP is the projection device;the capture speed of high-speed cameras far exceeds the projection frequency.Among various devices,an LED array can exceed the speed of a high-speed camera.However,non-sinusoidal fringe patterns in the LED array systems can arise from several factors that will reduce the accuracy,such as the spacing between adjacent LEDs,the inconsistency in brightness across different LEDs,and the residual high-order harmonics in binary defocusing projection.It is challenging to resolve by other methods.In this paper,we propose a method that creates a look-up table using system calibration data of phase-height models.Then we utilize the look-up table to compensate for the phase error during the reconstructing process.The foundation of the proposed method relies on the time-invariance of systematic error;any factor that impacts the sinusoidal characteristic would present as an anomaly in the unwrapped phase.Experiments have demonstrated that the root mean square errors(RMSEs)of the results yielded by the proposed method were reduced by over 90%compared to those yielded by the traditional method,reaching 20μm accuracy.This paper offers an alternative approach for high-speed and high-accuracy 3D imaging with an LED array and presents a workable solution for addressing complex errors from non-sinusoidal fringes.展开更多
Fringe projection profilometry,a powerful technique for three-dimensional(3D)imaging and measurement,has been revolutionized by deep learning,achieving speeds of up to 100,000 frames per second(fps)while preserving hi...Fringe projection profilometry,a powerful technique for three-dimensional(3D)imaging and measurement,has been revolutionized by deep learning,achieving speeds of up to 100,000 frames per second(fps)while preserving highresolution.This advancement expands its applications to high-speed transient scenarios,opening new possibilities for ultrafast 3D measurements.展开更多
Recent advances in imaging sensors and digital light projection technology have facilitated rapid progress in 3D optical sensing,enabling 3D surfaces of complexshaped objects to be captured with high resolution and ac...Recent advances in imaging sensors and digital light projection technology have facilitated rapid progress in 3D optical sensing,enabling 3D surfaces of complexshaped objects to be captured with high resolution and accuracy.Nevertheless,due to the inherent synchronous pattern projection and image acquisition mechanism,the temporal resolution of conventional structured light or fringe projection profilometry(FPP)based 3D imaging methods is still limited to the native detector frame rates.In this work,we demonstrate a new 3D imaging method,termed deep-learning-enabled multiplexed FPP(DLMFPP),that allows to achieve high-resolution and high-speed 3D imaging at near-one-order of magnitude-higher 3D frame rate with conventional low-speed cameras.By encoding temporal information in one multiplexed fringe pattern,DLMFPP harnesses deep neural networks embedded with Fourier transform,phase-shifting and ensemble learning to decompose the pattern and analyze separate fringes,furnishing a high signal-to-noise ratio and a ready-to-implement solution over conventional computational imaging techniques.We demonstrate this method by measuring different types of transient scenes,including rotating fan blades and bullet fired from a toy gun,at kHz using cameras of around 100 Hz.Experiential results establish that DLMFPP allows slow-scan cameras with their known advantages in terms of cost and spatial resolution to be used for high-speed 3D imaging tasks.展开更多
In 2019,the Event Horizon Telescope(EHT)released the first-ever image of a black hole event horizon.Astronomers are now aiming for higher angular resolutions of distant targets,like black holes,to understand more abou...In 2019,the Event Horizon Telescope(EHT)released the first-ever image of a black hole event horizon.Astronomers are now aiming for higher angular resolutions of distant targets,like black holes,to understand more about the fundamental laws of gravity that govern our universe.To achieve this higher resolution and increased sensitivity,larger radio telescopes are needed to operate at higher frequencies and in larger quantities.Projects like the next-generation Very Large Array(ngVLA)and the Square-Kilometer Array(SKA)require building hundreds of telescopes with diameters greater than 10 ms over the next decade.This has a twofold effect.Radio telescope surfaces need to be more accurate to operate at higher frequencies,and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities.Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution.This leads to faster and more accurate panel alignment and,therefore,a more productive observatory.In this paper,we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish.The measurement takes only 10 min and directly delivers feedback on the tip,tilt,and piston of each panel to create the ideal reflector shape.展开更多
The Fringe Projection Profilometry(FPP)system with a single exposure time or a single projection intensity is limited by the dynamic range of the camera,which can lead to overexposure and underexposure of the image,re...The Fringe Projection Profilometry(FPP)system with a single exposure time or a single projection intensity is limited by the dynamic range of the camera,which can lead to overexposure and underexposure of the image,resulting in point cloud loss or reduced accuracy.To address this issue,unlike the pixel modulation method of projectors,we utilize the characteristics of color projectors where the intensity of the three-channel LED can be controlled independently.We propose a method for separating the projector's three-channel light intensity,combined with a color camera,to achieve single exposure and multi-intensity image acquisition.Further,the crosstalk coefficient is applied to predict the three-channel reflectance of the measured object.By integrating clustering and channel mapping,we establish a pixel-level mapping model between the projector's three-channel current and the camera's three-channel image intensity,which realizes the optimal projection current prediction and the high dynamic range(HDR)image acquisition.The proposed method allows for high-precision three-dimensional(3D)data acquisition of HDR scenes with a single exposure.The effectiveness of this method has been validated through experiments with standard planes and standard steps,showing a significant reduction in mean absolute error(44.6%)compared to existing singleexposure HDR methods.Additionally,the number of images required for acquisition is significantly reduced(by 70.8%)compared to multi-exposure fusion methods.This proposed method has great potential in various FPP-related fields.展开更多
Fringe projection profilometry(FPP)has been extensively studied in the field of three-dimensional(3D)measurement.Although FPP always uses high-frequency fringes to ensure high measurement accuracy,too many patterns ar...Fringe projection profilometry(FPP)has been extensively studied in the field of three-dimensional(3D)measurement.Although FPP always uses high-frequency fringes to ensure high measurement accuracy,too many patterns are projected to unwrap the phase,which affects the speed of 3D reconstruction.We propose a high-speed 3D shape measurement method using only three high-frequency inner shifting-phase patterns(70 periods),which satisfies both high precision and high measuring speed requirements.Besides,our proposed method obtains the wrapped phase and the fringe order simultaneously without any other information and constraints.The proposed method has successfully reconstructed moving objects with high speed at the camera's full frame rate(1700 frames per second).展开更多
Quantitative phase microscopy by digital holography is a good candidate for high-speed,high precision profilometry.Multi-wavelength optical phase unwrapping avoids difficulties of numerical unwrapping methods,and can ...Quantitative phase microscopy by digital holography is a good candidate for high-speed,high precision profilometry.Multi-wavelength optical phase unwrapping avoids difficulties of numerical unwrapping methods,and can generate surface topographic images with large axial range and high axial resolution.But the large axial range is accompanied by proportionately large noise.An iterative process utilizing holograms acquired with a series of wavelengths is shown to be effective in reducing the noise to a few micrometers even over the axial range of several millimeters.An alternate approach with shifting of illumination angle,instead of using multiple laser sources,provides multiple effective wavelengths from a single laser,greatly simplifying the system complexity and providing great flexibility in the wavelength selection.Experiments are performed demonstrating the basic processes of multi-wavelength digital holography(MWDH)and multi-angle digital holography(MADH).Example images are presented for surface profiles of various types of surface structures.The methods have potential for versatile,high performance surface profilometry,with compact optical system and straightforward processing algorithms.展开更多
This study describes a novel fringe-shaping technique developed to alleviate the fringe truncation problem engendered by the acquired saturated and/or weak fringe images from high-/low-reflectance surfaces of three-di...This study describes a novel fringe-shaping technique developed to alleviate the fringe truncation problem engendered by the acquired saturated and/or weak fringe images from high-/low-reflectance surfaces of three-dimensional（3D） objects in phase-shifting profilometry. The particle swarm optimization algorithm is employed to perform the recovery of the truncated fringes with optimal fitting for compensation after single-trial acquisition. The results show that the proposed method improves phase recovery accuracy to accomplish 3 D surface reconstruction with only one set of phase-shifting fringes under different truncation sceneries.展开更多
Fringe projection profilometry(FPP)has been widely applied to non-contact three-dimensional measurement in industries owing to its high accuracy and speed.The point cloud,which is a measurement result of the FPP syste...Fringe projection profilometry(FPP)has been widely applied to non-contact three-dimensional measurement in industries owing to its high accuracy and speed.The point cloud,which is a measurement result of the FPP system,typically contains a large number of invalid points caused by the background,ambient light,shadows,and object edge regions.Research on noisy point detection and elimination has been conducted over the past two decades.However,existing invalid point removal methods are based on image intensity analysis and are only applicable to simple measurement backgrounds that are purely dark.In this paper,we propose a novel invalid point removal framework that consists of two aspects:(1)A convolutional neural network(CNN)is designed to segment the foreground from the background of different intensity conditions in FPP measurement circumstances to remove background points and the most discrete points in background regions.(2)A two-step method based on the fringe image intensity threshold and a bilateral filter is proposed to eliminate the small number of discrete points remaining after background segmentation caused by shadows and edge areas on objects.Experimental results verify that the proposed framework(1)can remove background points intelligently and accurately in different types of complex circumstances,and(2)performs excellently in discrete point detection from object regions.展开更多
基金supported by National Key Research and Development Program of China(2022YFB2804603,2022YFB2804605)National Natural Science Foundation of China(U21B2033)+4 种基金Fundamental Research Funds forthe Central Universities(2023102001,2024202002)National Key Laborato-ry of Shock Wave and Detonation Physics(JCKYS2024212111)China Post-doctoral Science Fund(2023T160318)Open Research Fund of JiangsuKey Laboratory of Spectral Imaging&Intelligent Sense(JSGP202105,JSGP202201)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX25_0695,SJCX25_0188)。
文摘Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pattern projection.However,the imaging speed of conventional fringe projection profilometry(FPP)remains limited by the native sensor refresh rates due to the inherent"one-to-one"synchronization mechanism between pattern projection and image acquisition in standard structured light techniques.Here,we present dual-frequency angular-multiplexed fringe projection profilometry(DFAMFPP),a deep learning-enabled 3D imaging technique that achieves high-speed,high-precision,and large-depth-range absolute 3D surface measurements at speeds 16 times faster than the sensor's native frame rate.By encoding multi-timeframe 3D information into a single multiplexed image using multiple pairs of dual-frequency fringes,high-accuracy absolute phase maps are reconstructed using specially trained two-stage number-theoretical-based deep neural networks.We validate the effectiveness of DFAMFPP through dynamic scene measurements,achieving 10,000 Hz 3D imaging of a running turbofan engine prototype with only a 625 Hz camera.By overcoming the sensor hardware bottleneck,DFAMFPP significantly advances high-speed and ultra-high-speed 3D imaging,opening new avenues for exploring dynamic processes across diverse scientific disciplines.
文摘Two- dimensional Fourier transform profilometry (2 -D FTP) for data acquisition of fabric surface shapes isproposed. Phase unwrapping technique based on digitalweighted filter and reliability mask are employed. Ex-perimentai results of shape measurement for several fab-ric appearances are given. From the measured results, itis shown that this method can make up for not only thedisadvantage of the gray level image analysis which isonly suitable for simple structure and solid - pattern fab-ric, but also the low speed and high cost of laser dotscanning technique.
基金This work was supported by National Natural Science Foundation of China(62075096,62005121,U21B2033)Leading Technology of Jiangsu Basic Research Plan(BK20192003)+4 种基金“333 Engineering”Research Project of Jiangsu Province(BRA2016407)Jiangsu Provincial“One belt and one road”innovation cooperation project(BZ2020007)Fundamental Research Funds for the Central Universities(30921011208,30919011222,30920032101)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21_0273)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging&Intelligent Sense(JSGP202105).
文摘Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a single fringe image.In this paper,we demonstrate that the deep neural networks can be trained to directly recover the absolute phase from a unique fringe image that involves spatially multiplexed fringe patterns of different frequencies.The extracted phase is free from spectrum-aliasing problem which is hard to avoid for traditional spatial-multiplexing methods.Experiments on both static and dynamic scenes show that the proposed approach is robust to object motion and can obtain high-quality 3D reconstructions of isolated objects within a single fringe image.
基金Project supported by the Science and Technology Major Projects of Zhejiang Province,China(Grant No.2013C03043-5)
文摘Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector-camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method.
基金the National Natural Science Foundation of China(No.10672065).
文摘2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.
文摘The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is able to automatically recognize any position between depression and elevation on an object surface.Theoretical analysis and experimental verification are presented.
基金National Key R and D Program of China,No.2018YFC2002202
文摘BACKGROUND Artificial urethral sphincter(AUS)implantation is currently the gold standard for treating moderate and severe urinary incontinence.Currently,cuffs are chosen based on the surgeon’s experience,and adjusting cuff tightness is crucial.The TDOC air-charged catheter has not been proven to be inferior to traditional catheters.We report how intraoperative urethral pressure profilometry is performed using a T-DOC air-charged catheter with ambulatory urodynamic equipment,to guide cuff selection and adjustment.CASE SUMMARY A 67-year-old man presented to our hospital with complete urinary incontinence following transurethral prostatectomy,using five pads/d to maintain local dryness.Preoperatively,the maximum urethral pressure(MUP)and maximum urethral closure pressure(MUCP)were 52 cmH2O and 17 cmH2O,respectively.An AUS was implanted.Intraoperatively,in the inactivated state,the MUP and MUCP were 53 cmH2O and 50 cmH2O,respectively;in the activated state,they were 112 cmH2O and 109 cmH2O,respectively.The pump was activated 6 wk postoperatively.Re-measurement of the urethral pressure on the same day showed that in the inactivated state,MUP and MUCP were 89 cmH2O and 51 cmH2O,respectively,and in the activated state,120 cmH2O and 92 cmH2O,respectively.One month after device activation,telephonic follow-up revealed that pad use had decreased from five pads/d to one pad/d,which met the standard for social continence(0-1 pad per day).There were no complications.CONCLUSION The relationship between intraoperative urethral pressure and urinary continence post-surgery can provide data for standardizing AUS implantation and evaluating efficacy.
文摘An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one step phase shift algorithm.In comparison with traditional phase shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.
基金Project (Nos. 2007AA04Z1A5 and 2007AA01Z311) supported by the Hi-Tech Research and Development Program (863) of China
文摘An integrated and reliable phase unwrapping algorithm is proposed based on residues and blocking-lines detection, closed contour extraction and quality map ordering for the measurement of 3D shapes by Fourier-transform profilometry (FTP). The proposed algorithm first detects the residues on the wrapped phase image, applies wavelet analysis to generate the blocking-lines that can just connect the residues of opposite polarity, then carries out the morphology operation to extract the closed contour of the shape, and finally uses the modulation intensity information and the Laplacian of Gaussian operation of the wrapped phase image as the quality map. The unwrapping process is completed from a region of high reliability to that of low reliability and the blocking-lines can prevent the phase error propagation effectively. Furthermore, by using the extracted closed contour to exclude the invalid areas from the phase unwrapping process, the algorithm becomes more efficient. The experiment shows the effec-tiveness of the new algorithm.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61173122, 60970098, 60803024, 90715043, and 61144006)the Postdoctoral Startup Foundation of Central South University, China (Grant No. 1332/74341016030)
文摘In Fourier transform profilometry （FTP）, we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device （CCD） and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical ex- planation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.
文摘In order to study the strength of the composite material plate problems, need to adopt a nondestructive testing method to obtain the specimen surface under the effect of high-speed impact regularity of shape. The projection profilometry was used to measure the surface profile or the full field deformation. Furtherly, by using the Fourier transform algorithm, there is only one frame of captured image</span><span style="font-family:Verdana;"> which</span><span style="font-family:Verdana;"> is needed in the measurement, so that it can be introduced into the high speed impaction procedure measurement. An experimental system, which was contained with an impact setup and the projection profilometry measurement part, was constructed for the impaction action characteristic research. The metallic impact object can be launched by a gas gun or a spin fan, respectively. The detected object </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> manufactured by composite materials. In order to increase the surface deformation measurement accuracy, the calibration method and the error was discussed with different calibration specimen. And then, the proposed profilometry measurement method is proved by the gas gun and spin fan projectile test. The surface deformation of the manufactured composite plates and fan case are measured in the impaction procedure. So that the impact action details can be described much more clearly than the traditional video monitoring method.
基金National Key Research and Development Program of China(2023YFB2806800)Open Research Projects of KLOMT(2022KLOMT02-02)。
文摘Fringe projection profilometry(FPP)is a method that determines height by analyzing distortional fringes,which is widely used in high-accuracy 3D imaging.Now,one major reason limiting imaging speed in FPP is the projection device;the capture speed of high-speed cameras far exceeds the projection frequency.Among various devices,an LED array can exceed the speed of a high-speed camera.However,non-sinusoidal fringe patterns in the LED array systems can arise from several factors that will reduce the accuracy,such as the spacing between adjacent LEDs,the inconsistency in brightness across different LEDs,and the residual high-order harmonics in binary defocusing projection.It is challenging to resolve by other methods.In this paper,we propose a method that creates a look-up table using system calibration data of phase-height models.Then we utilize the look-up table to compensate for the phase error during the reconstructing process.The foundation of the proposed method relies on the time-invariance of systematic error;any factor that impacts the sinusoidal characteristic would present as an anomaly in the unwrapped phase.Experiments have demonstrated that the root mean square errors(RMSEs)of the results yielded by the proposed method were reduced by over 90%compared to those yielded by the traditional method,reaching 20μm accuracy.This paper offers an alternative approach for high-speed and high-accuracy 3D imaging with an LED array and presents a workable solution for addressing complex errors from non-sinusoidal fringes.
文摘Fringe projection profilometry,a powerful technique for three-dimensional(3D)imaging and measurement,has been revolutionized by deep learning,achieving speeds of up to 100,000 frames per second(fps)while preserving highresolution.This advancement expands its applications to high-speed transient scenarios,opening new possibilities for ultrafast 3D measurements.
基金supported by National Key Research and Development Program of China(2022YFB2804603)National Natural Science Foundation of China(62075096,62005121,U21B2033)+3 种基金Leading Technology of Jiangsu Basic Research Plan(BK20192003)“333 Engineering”Research Project of Jiangsu Province(BRA2016407)Fundamental Research Funds for the Central Universities(30921011208,30919011222,30920032101)Fundamental Research Funds for the Central Universities(2023102001,2024202002).
文摘Recent advances in imaging sensors and digital light projection technology have facilitated rapid progress in 3D optical sensing,enabling 3D surfaces of complexshaped objects to be captured with high resolution and accuracy.Nevertheless,due to the inherent synchronous pattern projection and image acquisition mechanism,the temporal resolution of conventional structured light or fringe projection profilometry(FPP)based 3D imaging methods is still limited to the native detector frame rates.In this work,we demonstrate a new 3D imaging method,termed deep-learning-enabled multiplexed FPP(DLMFPP),that allows to achieve high-resolution and high-speed 3D imaging at near-one-order of magnitude-higher 3D frame rate with conventional low-speed cameras.By encoding temporal information in one multiplexed fringe pattern,DLMFPP harnesses deep neural networks embedded with Fourier transform,phase-shifting and ensemble learning to decompose the pattern and analyze separate fringes,furnishing a high signal-to-noise ratio and a ready-to-implement solution over conventional computational imaging techniques.We demonstrate this method by measuring different types of transient scenes,including rotating fan blades and bullet fired from a toy gun,at kHz using cameras of around 100 Hz.Experiential results establish that DLMFPP allows slow-scan cameras with their known advantages in terms of cost and spatial resolution to be used for high-speed 3D imaging tasks.
基金funded by the National Science Foundation(NSF)Award 2009384.
文摘In 2019,the Event Horizon Telescope(EHT)released the first-ever image of a black hole event horizon.Astronomers are now aiming for higher angular resolutions of distant targets,like black holes,to understand more about the fundamental laws of gravity that govern our universe.To achieve this higher resolution and increased sensitivity,larger radio telescopes are needed to operate at higher frequencies and in larger quantities.Projects like the next-generation Very Large Array(ngVLA)and the Square-Kilometer Array(SKA)require building hundreds of telescopes with diameters greater than 10 ms over the next decade.This has a twofold effect.Radio telescope surfaces need to be more accurate to operate at higher frequencies,and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities.Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution.This leads to faster and more accurate panel alignment and,therefore,a more productive observatory.In this paper,we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish.The measurement takes only 10 min and directly delivers feedback on the tip,tilt,and piston of each panel to create the ideal reflector shape.
文摘The Fringe Projection Profilometry(FPP)system with a single exposure time or a single projection intensity is limited by the dynamic range of the camera,which can lead to overexposure and underexposure of the image,resulting in point cloud loss or reduced accuracy.To address this issue,unlike the pixel modulation method of projectors,we utilize the characteristics of color projectors where the intensity of the three-channel LED can be controlled independently.We propose a method for separating the projector's three-channel light intensity,combined with a color camera,to achieve single exposure and multi-intensity image acquisition.Further,the crosstalk coefficient is applied to predict the three-channel reflectance of the measured object.By integrating clustering and channel mapping,we establish a pixel-level mapping model between the projector's three-channel current and the camera's three-channel image intensity,which realizes the optimal projection current prediction and the high dynamic range(HDR)image acquisition.The proposed method allows for high-precision three-dimensional(3D)data acquisition of HDR scenes with a single exposure.The effectiveness of this method has been validated through experiments with standard planes and standard steps,showing a significant reduction in mean absolute error(44.6%)compared to existing singleexposure HDR methods.Additionally,the number of images required for acquisition is significantly reduced(by 70.8%)compared to multi-exposure fusion methods.This proposed method has great potential in various FPP-related fields.
基金supported by the National Key Research and Development Program of China(No.2018YFB2001400)the Innovation Group Science Fund of Chongqing Natural Science Foundation(No.cstc2019jcyj-cxttX0003)。
文摘Fringe projection profilometry(FPP)has been extensively studied in the field of three-dimensional(3D)measurement.Although FPP always uses high-frequency fringes to ensure high measurement accuracy,too many patterns are projected to unwrap the phase,which affects the speed of 3D reconstruction.We propose a high-speed 3D shape measurement method using only three high-frequency inner shifting-phase patterns(70 periods),which satisfies both high precision and high measuring speed requirements.Besides,our proposed method obtains the wrapped phase and the fringe order simultaneously without any other information and constraints.The proposed method has successfully reconstructed moving objects with high speed at the camera's full frame rate(1700 frames per second).
文摘Quantitative phase microscopy by digital holography is a good candidate for high-speed,high precision profilometry.Multi-wavelength optical phase unwrapping avoids difficulties of numerical unwrapping methods,and can generate surface topographic images with large axial range and high axial resolution.But the large axial range is accompanied by proportionately large noise.An iterative process utilizing holograms acquired with a series of wavelengths is shown to be effective in reducing the noise to a few micrometers even over the axial range of several millimeters.An alternate approach with shifting of illumination angle,instead of using multiple laser sources,provides multiple effective wavelengths from a single laser,greatly simplifying the system complexity and providing great flexibility in the wavelength selection.Experiments are performed demonstrating the basic processes of multi-wavelength digital holography(MWDH)and multi-angle digital holography(MADH).Example images are presented for surface profiles of various types of surface structures.The methods have potential for versatile,high performance surface profilometry,with compact optical system and straightforward processing algorithms.
基金supported by the Ministry of Science and Technology(MOST 104-2221-E-034-010-MY3),Taiwan,China
文摘This study describes a novel fringe-shaping technique developed to alleviate the fringe truncation problem engendered by the acquired saturated and/or weak fringe images from high-/low-reflectance surfaces of three-dimensional（3D） objects in phase-shifting profilometry. The particle swarm optimization algorithm is employed to perform the recovery of the truncated fringes with optimal fitting for compensation after single-trial acquisition. The results show that the proposed method improves phase recovery accuracy to accomplish 3 D surface reconstruction with only one set of phase-shifting fringes under different truncation sceneries.
基金Supported by National Defense Basic Scientific Research Program of China(Grant No.JCKY2021602B032)。
文摘Fringe projection profilometry(FPP)has been widely applied to non-contact three-dimensional measurement in industries owing to its high accuracy and speed.The point cloud,which is a measurement result of the FPP system,typically contains a large number of invalid points caused by the background,ambient light,shadows,and object edge regions.Research on noisy point detection and elimination has been conducted over the past two decades.However,existing invalid point removal methods are based on image intensity analysis and are only applicable to simple measurement backgrounds that are purely dark.In this paper,we propose a novel invalid point removal framework that consists of two aspects:(1)A convolutional neural network(CNN)is designed to segment the foreground from the background of different intensity conditions in FPP measurement circumstances to remove background points and the most discrete points in background regions.(2)A two-step method based on the fringe image intensity threshold and a bilateral filter is proposed to eliminate the small number of discrete points remaining after background segmentation caused by shadows and edge areas on objects.Experimental results verify that the proposed framework(1)can remove background points intelligently and accurately in different types of complex circumstances,and(2)performs excellently in discrete point detection from object regions.
