470 research outputs found
Comparison of automated post-processing techniques for measurement of body surface area from 3D photonic scans
Body surface area (BSA) measurement is important in engineering and medicine fields to determine parameters for various applications. Three-dimensional scanning techniques may be used to acquire the BSA directly. Nevertheless, the raw data obtained from 3D scanning usually requires some manual post-processing which is time-consuming and requires technical expertise. Automated post-processing of 3D scans enables expedient BSA calculation with minimal technical expertise. The purpose of this research was to compare the accuracy and reliability of three different automated post-processing techniques including Stitched Puppet (SP), Poisson surface reconstruction (PSR), and screened Poisson surface reconstruction (SPSR) using manual post-processing as the criterion. Twenty-nine participants were scanned twice, and raw data were processed with the manual operation and automated techniques to acquire BSAs separately. The reliability of BSAs acquired from these approaches was represented by the relative technical error of measurements (TEM). Pearson’s regressions were applied to correct BSAs acquired from the automated techniques. The limits of agreement (LOA) were used to quantify the accuracy of BSAs acquired from the automated techniques and corrected by regression models. The reliability (relative TEM) of BSAs obtained from PSR, SPSR and SP were 0.32%, 0.30%, 0.82% respectively. After removing bias with the regression models, the LOA for PSR, SPSR and SP were (-0.0134 m2, 0.0135 m2), ±0.0131 m2, ±0.0573 m2 respectively. It is concluded that PSR and SPSR are good alternative approaches to manual post-processing for applications that need reliable and accurate measurements of BSAs with large populations
Active Image-based Modeling with a Toy Drone
Image-based modeling techniques can now generate photo-realistic 3D models
from images. But it is up to users to provide high quality images with good
coverage and view overlap, which makes the data capturing process tedious and
time consuming. We seek to automate data capturing for image-based modeling.
The core of our system is an iterative linear method to solve the multi-view
stereo (MVS) problem quickly and plan the Next-Best-View (NBV) effectively. Our
fast MVS algorithm enables online model reconstruction and quality assessment
to determine the NBVs on the fly. We test our system with a toy unmanned aerial
vehicle (UAV) in simulated, indoor and outdoor experiments. Results show that
our system improves the efficiency of data acquisition and ensures the
completeness of the final model.Comment: To be published on International Conference on Robotics and
Automation 2018, Brisbane, Australia. Project Page:
https://huangrui815.github.io/active-image-based-modeling/ The author's
personal page: http://www.sfu.ca/~rha55
Integrated Digital Reconstruction of Welded Components: Supporting Improved Fatigue Life Prediction
In the design of offshore jacket foundations, fatigue life is crucial.
Post-weld treatment has been proposed to enhance the fatigue performance of
welded joints, where particularly high-frequency mechanical impact (HFMI)
treatment has been shown to improve fatigue performance significantly.
Automated HFMI treatment has improved quality assurance and can lead to
cost-effective design when combined with accurate fatigue life prediction.
However, the finite element method (FEM), commonly used for predicting fatigue
life in complex or multi-axial joints, relies on a basic CAD depiction of the
weld, failing to consider the actual weld geometry and defects. Including the
actual weld geometry in the FE model improves fatigue life prediction and
possible crack location prediction but requires a digital reconstruction of the
weld. Current digital reconstruction methods are time-consuming or require
specialised scanning equipment and potential component relocation. The proposed
framework instead uses an industrial manipulator combined with a line scanner
to integrate digital reconstruction as part of the automated HFMI treatment
setup. This approach applies standard image processing, simple filtering
techniques, and non-linear optimisation for aligning and merging overlapping
scans. A screened Poisson surface reconstruction finalises the 3D model to
create a meshed surface. The outcome is a generic, cost-effective, flexible,
and rapid method that enables generic digital reconstruction of welded parts,
aiding in component design, overall quality assurance, and documentation of the
HFMI treatment.Comment: 6 pages, 7 figures, submitted to 2023 IEEE International Conference
on Imaging Systems and Techniques (IST2023
Validation of close-range photogrammetry for architectural and archaeological heritage Analysis of point density and 3D mesh geometry
The 3D digitization and Building Information Modeling (BIM), which is based on parametric objects, have considerably advanced by developing massive data capture techniques. Thus, reverse engineering currently plays a major role as these technologies capture accurately and efficiently the geometry, color and textures of complex architectural, archaeological and cultural heritage. This paper aims to validate close-range Structure from Motion (SfM) for heritage by analyzing the point density and the 3D mesh geometry in comparison with Terrestrial Laser Scanning (TLS). The accuracy of the results and the geometry mainly depends on the processing performed on the point set. Therefore,
these two variables are significant in the 3D reconstruction of heritage buildings. This paper focuses on a 15th century case study in Seville (Spain): the main façade of Casa de Pilatos. Ten SfM surveys were carried out varying the capture method (simple and stereoscopic) and the number of shots, distances, orientation and procedure. A mathematical analysis is proposed to verify the point spatial resolution and the accuracy of the 3D model geometry by section profiles in SfM data. SfM achieved acceptable accuracy levels to generate 3D meshes despite disordered shots and the number of images. Hence, stereoscopic photography using new instruments improved the results of close-range
photogrammetry while reducing the required number of photographs
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