A fast 3D reconstruction method based on structured light to measure various parameters of the raceway groove is presented. Digital parallel grating stripes distributed with sine density are projected onto the raceway...A fast 3D reconstruction method based on structured light to measure various parameters of the raceway groove is presented. Digital parallel grating stripes distributed with sine density are projected onto the raceway groove by a DLP projector, and distorting of stripes is happened on the raceway. Simultaneously, aided by three-step phase-shifting approach, three images covered by different stripes are obtained by a high-resolution CCD camera at the same location, thus a more accuracy local topography can be obtained. And then the bearing is rotated on a high precision computer controlled rotational stage. Three images are also obtained as the former step at next planned location triggered by the motor. After one cycle, all images information is combined through the mosaics. As a result, the 3D information of raceway groove can be gained. Not only geometric properties but also surface flaws can be extracted by software. A preliminary hardware system has been built, with which some geometric parameters have been extracted from reconstructed local topography.展开更多
Phase unwrapping is one of the key roles in fringe projection three-dimensional(3D)measurement technology.We propose a new method to achieve phase unwrapping in camera array light filed fringe projection 3D measuremen...Phase unwrapping is one of the key roles in fringe projection three-dimensional(3D)measurement technology.We propose a new method to achieve phase unwrapping in camera array light filed fringe projection 3D measurement based on deep learning.A multi-stream convolutional neural network(CNN)is proposed to learn the mapping relationship between camera array light filed wrapped phases and fringe orders of the expected central view,and is used to predict the fringe order to achieve the phase unwrapping.Experiments are performed on the light field fringe projection data generated by the simulated camera array fringe projection measurement system in Blender and by the experimental 3×3 camera array light field fringe projection system.The performance of the proposed network with light field wrapped phases using multiple directions as network input data is studied,and the advantages of phase unwrapping based on deep learning in light filed fringe projection are demonstrated.展开更多
AIM: To quantitatively analyze the retinal intermediate and deep capillary plexus(ICP and DCP) in patients with retinal deep vascular complex ischemia(RDVCI), using 3D projection artifacts removal(3D PAR) optical cohe...AIM: To quantitatively analyze the retinal intermediate and deep capillary plexus(ICP and DCP) in patients with retinal deep vascular complex ischemia(RDVCI), using 3D projection artifacts removal(3D PAR) optical coherence tomography angiography(OCTA).METHODS: RDVCI patients and gender-and agematched healthy controls were assessed and underwent OCTA examinations. The parafoveal vessel density(PFVD) of retinal deep vascular complex(DVC), ICP, and DCP were analyzed, and the percentage of reduction(PR) of PFVD was calculated.RESULTS: Twenty-four eyes in 22 RDVCI patients(20 in acute phase and 4 in chronic phase) and 24 eyes of 22 healthy subjects were enrolled as the control group. Significant reduction of PFVD in DVC, ICP, and DCP was observed in comparison with the controls(DVC: acute: 43.59%±6.58% vs 49.92%±5.49%, PR=12.69%;chronic: 43.50%±3.33% vs 51.20%±3.80%, PR=15.04%. ICP: acute: 40.28%±7.91% vs 46.97%±7.14%, PR=14.23%;chronic: 41.48%±2.87% vs 46.43%±3.29%, PR=10.66%. DCP: acute: 45.44%±8.27% vs 51.51%±9.97%, PR=11.79%;chronic: 37.78%±3.48% vs 51.73%±5.17%, PR=26.97%;all P<0.05). No significant PR difference was found among DVC, ICP, and DCP of RDVCI in acute phase(P=0.812), but significant difference in chronic phase(P=0.006, DVC vs DCP, ICP vs DCP). No significant difference in PR between acute and chronic phases in the DVC(P=0.735) or ICP(P=0.681) was found, but significant difference in the DCP(P=0.041).CONCLUSION: The PFVD of DVC, ICP, and DCP in RDVCI is significantly decreased in both acute and chronic phases. ICP impairment is stabilized from acute to chronic phase in RDVCI, whereas subsequent DCP impairment is uncovered and can be explained by ischemia-reperfusion damage.展开更多
Hydroxyapatite(HA)bioceramics have garnered considerable attention owing to their applications in the field of bone repair and excellent biocompatibility.Compared to extrusion-based 3D printing,projection-based 3D pri...Hydroxyapatite(HA)bioceramics have garnered considerable attention owing to their applications in the field of bone repair and excellent biocompatibility.Compared to extrusion-based 3D printing,projection-based 3D print-ing(3DPP)can fabricate parts with complex geometry,high accuracy,and efficiency,which is very promising for bioceramic scaffolds.However,conventional 3DPP using a paste with low viscosity will cause severe shrinkage of the parts after sintering,which makes it unsuitable for bioceramic scaffolds,and a system investigation of the printing process remains insufficient.In this study,we proposed a 3DPP device suitable for bioceramic scaffolds and investigated the additive manufacturing of HA scaffolds.Ceramic paste properties and process parameters of curing,debinding,and sintering were initially examined.The mechanical properties,shrinkage,and biocompati-bility in vitro of the sintered samples were further investigated.The obtained results indicate that HA bioceramics with uniform morphology,complex structure,and high accuracy can be manufactured using the 3DPP equip-ment.HA scaffolds have the mechanical strength of human cancellous bone,while HA scaffolds cultured with osteoblast precursor cells possess strong biocompatibility and can promote osteoblast adhesion,proliferation,and differentiation.These results suggest a promising application of the 3DPP technique in the preparation of bioceramic scaffolds,and the HA scaffolds fabricated using the 3DPP technique exhibit promising potential in fulfilling a constructive role in the biomedical field of human bone regeneration repair.展开更多
基金This project is supported by National Natural Science Foundation ofChina (No.50375047).
文摘A fast 3D reconstruction method based on structured light to measure various parameters of the raceway groove is presented. Digital parallel grating stripes distributed with sine density are projected onto the raceway groove by a DLP projector, and distorting of stripes is happened on the raceway. Simultaneously, aided by three-step phase-shifting approach, three images covered by different stripes are obtained by a high-resolution CCD camera at the same location, thus a more accuracy local topography can be obtained. And then the bearing is rotated on a high precision computer controlled rotational stage. Three images are also obtained as the former step at next planned location triggered by the motor. After one cycle, all images information is combined through the mosaics. As a result, the 3D information of raceway groove can be gained. Not only geometric properties but also surface flaws can be extracted by software. A preliminary hardware system has been built, with which some geometric parameters have been extracted from reconstructed local topography.
基金the National Natural Science Foundation of China(No.61905178)the Science&Technology Development Fund of Tianjin Education Commission for Higher Education(No.2019KJ021)the Natural Science Foundation of Tianjin(No.18JCQNJC71100)。
文摘Phase unwrapping is one of the key roles in fringe projection three-dimensional(3D)measurement technology.We propose a new method to achieve phase unwrapping in camera array light filed fringe projection 3D measurement based on deep learning.A multi-stream convolutional neural network(CNN)is proposed to learn the mapping relationship between camera array light filed wrapped phases and fringe orders of the expected central view,and is used to predict the fringe order to achieve the phase unwrapping.Experiments are performed on the light field fringe projection data generated by the simulated camera array fringe projection measurement system in Blender and by the experimental 3×3 camera array light field fringe projection system.The performance of the proposed network with light field wrapped phases using multiple directions as network input data is studied,and the advantages of phase unwrapping based on deep learning in light filed fringe projection are demonstrated.
基金Supported by the National Natural Science Foundation of China (No.81900911)the National Key R&D Program of China (No.2016YFC0904800,No.2019YFC0840607)+1 种基金the National Science and Technology Major Project of China (No.2017ZX09304010)the Interdisciplinary Program of Shanghai Jiao Tong University (No.YG2019QN66)。
文摘AIM: To quantitatively analyze the retinal intermediate and deep capillary plexus(ICP and DCP) in patients with retinal deep vascular complex ischemia(RDVCI), using 3D projection artifacts removal(3D PAR) optical coherence tomography angiography(OCTA).METHODS: RDVCI patients and gender-and agematched healthy controls were assessed and underwent OCTA examinations. The parafoveal vessel density(PFVD) of retinal deep vascular complex(DVC), ICP, and DCP were analyzed, and the percentage of reduction(PR) of PFVD was calculated.RESULTS: Twenty-four eyes in 22 RDVCI patients(20 in acute phase and 4 in chronic phase) and 24 eyes of 22 healthy subjects were enrolled as the control group. Significant reduction of PFVD in DVC, ICP, and DCP was observed in comparison with the controls(DVC: acute: 43.59%±6.58% vs 49.92%±5.49%, PR=12.69%;chronic: 43.50%±3.33% vs 51.20%±3.80%, PR=15.04%. ICP: acute: 40.28%±7.91% vs 46.97%±7.14%, PR=14.23%;chronic: 41.48%±2.87% vs 46.43%±3.29%, PR=10.66%. DCP: acute: 45.44%±8.27% vs 51.51%±9.97%, PR=11.79%;chronic: 37.78%±3.48% vs 51.73%±5.17%, PR=26.97%;all P<0.05). No significant PR difference was found among DVC, ICP, and DCP of RDVCI in acute phase(P=0.812), but significant difference in chronic phase(P=0.006, DVC vs DCP, ICP vs DCP). No significant difference in PR between acute and chronic phases in the DVC(P=0.735) or ICP(P=0.681) was found, but significant difference in the DCP(P=0.041).CONCLUSION: The PFVD of DVC, ICP, and DCP in RDVCI is significantly decreased in both acute and chronic phases. ICP impairment is stabilized from acute to chronic phase in RDVCI, whereas subsequent DCP impairment is uncovered and can be explained by ischemia-reperfusion damage.
基金supported by National Natural Science Foundation of China(Grant Nos.51805475,81827804)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY22E050011)+1 种基金Open Founda-tion of the State Key Laboratory of Fluid Power and Mechatronic Sys-tems(Grant No.GZKF-202102)Jiangsu Key Laboratory of 3D Print-ing Equipment and Manufacturing(Grant No.3DL202105).
文摘Hydroxyapatite(HA)bioceramics have garnered considerable attention owing to their applications in the field of bone repair and excellent biocompatibility.Compared to extrusion-based 3D printing,projection-based 3D print-ing(3DPP)can fabricate parts with complex geometry,high accuracy,and efficiency,which is very promising for bioceramic scaffolds.However,conventional 3DPP using a paste with low viscosity will cause severe shrinkage of the parts after sintering,which makes it unsuitable for bioceramic scaffolds,and a system investigation of the printing process remains insufficient.In this study,we proposed a 3DPP device suitable for bioceramic scaffolds and investigated the additive manufacturing of HA scaffolds.Ceramic paste properties and process parameters of curing,debinding,and sintering were initially examined.The mechanical properties,shrinkage,and biocompati-bility in vitro of the sintered samples were further investigated.The obtained results indicate that HA bioceramics with uniform morphology,complex structure,and high accuracy can be manufactured using the 3DPP equip-ment.HA scaffolds have the mechanical strength of human cancellous bone,while HA scaffolds cultured with osteoblast precursor cells possess strong biocompatibility and can promote osteoblast adhesion,proliferation,and differentiation.These results suggest a promising application of the 3DPP technique in the preparation of bioceramic scaffolds,and the HA scaffolds fabricated using the 3DPP technique exhibit promising potential in fulfilling a constructive role in the biomedical field of human bone regeneration repair.