scholarly journals 3D MEASUREMENT COMBINING MULTI-VIEW AND MULTI-FOCUS IMAGES USING LIGHT FIELD CAMERA

2020 ◽  
Vol V-2-2020 ◽  
pp. 633-640
Author(s):  
T. Fuse ◽  
Y. Kajihara
Keyword(s):  
Rigid Body ◽  
Light Field ◽  
Computational Photography ◽  
Measurement Time ◽  
3D Measurement ◽  
3D Measurements ◽  
Calculation Processing ◽  
Future Work ◽  
Shape From Focus

Abstract. In recent years, the demand for inexpensive, simple, and highly accurate 3D measurement has been increasing. Representative methods, photogrammetry, and shape from focus (SfF) have limitations in terms of measurement time and labour. In order to solve them, computational photography (CP) has been proposed. A light field camera, based on CP, has also been developed. It has a feature to acquire multi-view and multi-focus images simultaneously in one shot. It is possible to perform 3D measurements with less time and labour for photographing and calculation processing using these images. In this study, we combined the photogrammetry as applied to multi-view images with the SfF as applied to multi-focus images using a light field camera. We applied the proposed method to a rigid body and verified its accuracy. We confirmed that the proposed method achieved more accurate results than the photogrammetry and the SfF method. Furthermore, we applied the proposed method to screws and cracks on walls of buildings and affirmed its applicability. Finally, we suggested future work on the developed method.

Light field 3D measurement using unfocused plenoptic cameras

2018 ◽  
Vol 43 (15) ◽  
pp. 3746 ◽  
Author(s):  
Zewei Cai ◽  
Xiaoli Liu ◽  
Qijian Tang ◽  
Xiang Peng ◽  
Bruce Zhi Gao
Keyword(s):  
Light Field ◽  
3D Measurement

scholarly journals Learning-based active 3D measurement technique using light field created by video projectors

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuki Shiba ◽  
Satoshi Ono ◽  
Ryo Furukawa ◽  
Shinsaku Hiura ◽  
Hiroshi Kawasaki
Keyword(s):  
Measurement Technique ◽  
Light Field ◽  
3D Measurement

Dynamic Analysis of Rigid-Body Mechanisms Mounted on Flexible Support Structures — Planar Case

2006 ◽  
Vol 505-507 ◽  
pp. 589-594 ◽  
Author(s):  
Huai Ku Sun ◽  
Cun Gin Chen ◽  
Yu Chen Shen
Keyword(s):  
Rigid Body ◽  
Dynamic Analysis ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Support Structures ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Planar Case ◽  
Flexible Support ◽  
Future Work

Computer-aided analysis of rigid-body mechanisms is combined with the finite element analysis of flexible structures to develop a computer model and derive the equation of motion, incorporating the Lagrange multiplier, to be used in the dynamic analysis of multi-rigid-body mechanisms mounted on flexible support structures. The resulting equations are solved by numerical integration. Predicting and analyzing the performance of the full system, including the motion of the system components and the forcing condition, during the engineering design process will promote the success of the entire system. Finally, a machine gun system with a flexible mount is given as a numerical example. The results reveal that the interaction between the rigid-body mechanisms and its flexible support structures importantly determines the performance of whole system. This study considers only the planar case. Our future work will propose a more complicated fully three-dimensional model.

scholarly journals Accuracy of image-free navigation in intraoperative leg length change from total hip arthroplasty using evaluations from 2D and 3D measurements

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Shine Tone ◽  
Masahiro Hasegawa ◽  
Yohei Naito ◽  
Hiroki Wakabayashi ◽  
Akihiro Sudo
Keyword(s):  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Strong Correlation ◽  
Length Change ◽  
3D Measurement ◽  
Leg Length ◽  
Absolute Value ◽  
Total Hip ◽  
3D Measurements ◽  
2D And 3D

Abstract Background Leg length discrepancy is one of the most common problems after total hip arthroplasty (THA). The aim of this study was to investigate the accuracy of image-free navigation in intraoperative leg length change (LLC) using evaluations from anteroposterior radiographs (2D measurement) and 3D bone models using CT data (3D measurement). Methods One hundred THAs with cementless cups and stems were performed using an image-free navigation system in our hospital. We evaluated the accuracy of image-free navigation based on LLC from 2D and 3D measurements. Furthermore, we also investigated error in absolute value and correlations between 2D and 3D measurements in LLC. Results The accuracy of image-free navigation based on 2D measurement was 94% within 5 mm and 76% within 3 mm. The accuracy of image-free navigation based on 3D measurement was 92% within 5 mm and 81% within 3 mm. The error in absolute value in LLC between 2D and 3D measurements was 1.7 ± 1.4 mm (range, 0 to 6 mm). A strong correlation was observed between 2D and 3D measurements in the LLC. Conclusions In the present study, good accuracy of image-free navigation in intraoperative LLC was confirmed for both evaluation methods from 2D and 3D measurements. In addition, the error in absolute value in the LLC between 2D and 3D measurements was very small, and we observed a strong correlation between 2D and 3D measurements. Based on these results, evaluation of LLC from radiographs was considered sufficient if radiographs can be taken accurately.

scholarly journals Comparative study of glenoid version and inclination using two-dimensional images from computed tomography and three-dimensional reconstructed bone models

2020 ◽  
Vol 23 (3) ◽  
pp. 119-124
Author(s):  
Chang-Hyuk Choi ◽  
Hee-Chan Kim ◽  
Daewon Kang ◽  
Jun-Young Kim
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Ct Scans ◽  
3D Measurement ◽  
Two Dimensional ◽  
Glenoid Version ◽  
Observer Reliability ◽  
3D Measurements ◽  
Orthopedic Surgeons ◽  
2D Images

Background: This study was performed to compare glenoid version and inclination measured using two-dimensional (2D) images from computed tomography (CT) scans or three-dimensional (3D) reconstructed bone models.Methods: Thirty patients who had undergone conventional CT scans were included. Two orthopedic surgeons measured glenoid version and inclination three times on 2D images from CT scans (2D measurement), and two other orthopedic surgeons performed the same measurements using 3D reconstructed bone models (3D measurement). The 3D-reconstructed bone models were acquired and measured with Mimics and 3-Matics (Materialise).Results: Mean glenoid version and inclination in 2D measurements were –1.705º and 9.08º, respectively, while those in 3D measurements were 2.635º and 7.23º. The intra-observer reliability in 2D measurements was 0.605 and 0.698, respectively, while that in 3D measurements was 0.883 and 0.892. The inter-observer reliability in 2D measurements was 0.456 and 0.374, respectively, while those in 3D measurements was 0.853 and 0.845.Conclusions: The difference between 2D and 3D measurements is not due to differences in image data but to the use of different tools. However, more consistent results were obtained in 3D measurement. Therefore, 3D measurement can be a good alternative for measuring glenoid version and inclination.

scholarly journals Polarized Light Field Imaging for Single-Shot Reflectance Separation

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3803 ◽  
Author(s):  
Jaewon Kim ◽  
Abhijeet Ghosh
Keyword(s):  
Light Field ◽  
Polarized Light ◽  
Angular Separation ◽  
Single Scattering ◽  
Computational Photography ◽  
Single Shot ◽  
Specular Reflectance ◽  
Structured Lighting ◽  
Separation Results ◽  
Imaging Conditions

We present a novel computational photography technique for single-shot separation of diffuse/specular reflectance, as well as novel angular domain separation of layered reflectance. We present two imaging solutions for this purpose: two-way polarized light-field (TPLF) imaging and four-way polarized light-field (FPLF) imaging. TPLF imaging consists of a polarized light-field camera, which simultaneously captures two orthogonal states of polarization. A single photograph of a subject acquired with the TPLF camera under polarized illumination then enables standard separation of diffuse (depolarizing) and polarization preserving specular reflectance using light-field sampling. We further demonstrate that the acquired data also enable novel angular separation of layered reflectance including separation of specular reflectance and single scattering in the polarization preserving component, as well as separation of shallow scattering from deep scattering in the depolarizing component. FPLF imaging further generalized the functionality of TPLF imaging under uncontrolled unpolarized or partially polarized illumination such as outdoors. We apply our approach for efficient acquisition of facial reflectance including diffuse and specular normal maps and novel separation of photometric normals into layered reflectance normals for layered facial renderings. We validate our proposed single-shot layered reflectance separation under various imaging conditions and demonstrate it to be comparable to an existing multi-shot technique that relies on structured lighting while achieving separation results under a variety of illumination conditions.

A 3D Measurement Method Based on Three Frequencies PSP

2014 ◽  
Vol 701-702 ◽  
pp. 471-474
Author(s):  
Li Mei Song ◽  
Guang Xin Xing ◽  
Peng Qiang Wang ◽  
Jiang Tao Xi ◽  
Qing Hua Guo
Keyword(s):  
3D Reconstruction ◽  
Precision Measurement ◽  
Measurement Method ◽  
Three Dimensional ◽  
Trigonometric Function ◽  
Phase Unwrapping ◽  
Optical Information ◽  
3D Measurement ◽  
High Precision Measurement ◽  
3D Measurements

This paper proposes a method of global phase unwrapping used in multi-frequency three-dimensional (3D) measurements. In this method, three kinds of optical information which change in accordance with trigonometric function (sine or cosine) to the objects. The optical information cycles is P1, P2 and P3. Each waveform should 4-8 steps phase shifts. Then, calculate the phase value of each cycle. The composited phase value of two cycles and the final composited phase value of three cycles are calculated by image shift of each cycle. Finally, calculate the global phase value of each cycle based on the composited phase, thus, all the 3D coordinates of objects can be obtain after 3D reconstruction. The proposed method can solves the object surfaces color changing largely in 3D measurements. This method realizes high precision measurement without spray developer and achieves the protection of the environment.

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