An affordable surround-screen virtual reality display

Building a projection-based virtual reality display is a time, cost, and resource intensive enterprise andmany details contribute to the final display quality. This is especially true for surround-screen displays wheremost of them are one-of-a-kind systems or custom-made installations with specialized projectors, framing, andprojection screens. In general, the costs of acquiring these types of systems have been in the hundreds and evenmillions of dollars, specifically for those supporting synchronized stereoscopic projection across multiple screens.Furthermore, the maintenance of such systems adds an additional recurrent cost, which makes them hard to affordfor a general introduction in a wider range of industry, academic, and research communities.We present a low-cost, easy to maintain surround-screen design based on off-the-shelf affordable componentsfor the projection screens, framing, and display system. The resulting system quality is comparable to significantlymore expensive commercially available solutions. Additionally, users with average knowledge can implement ourdesign and it has the added advantage that single components can be individually upgraded based on necessity aswell as available funds

Two dimensional angular domain optical imaging in biological tissues

Optical imaging is a modality that can detect optical contrast within a biological sample that is not detectable with other conventional imaging techniques. Optical trans-illumination images of tissue samples are degraded by optical scatter. Angular Domain Imaging (ADI) is an optical imaging technique that filters scattered photons based on the trajectory of the photons. Previous angular filters were limited to one dimensional arrays, greatly limiting the imaging capability of the system. We have developed a 2D Angular Filter Array (AFA) that is capable of acquiring two dimensional projection images of a sample. The AFA was constructed using rapid prototyping techniques. The contrast and the resolution of the AFA was evaluated. The results suggest that a 2D AFA can be used to acquire two dimensional projection images of a sample with a reduced acquisition time compared to a scanning 1D AFA

An Embedded Approach to Volumetric Displays

The goal of this capstone project was to design and create and test a functioning volumetric display system. This project created an embedded solution for a volumetric display that can perform the necessary data manipulations required to prepare and slice a three-dimensional object for so that it can be displayed in real space

Volumetric Display Research

The goal of this project was to research and develop a volumetric display system that allows a three-dimensional CAD file to be displayed in real space. The system used a Xilinx Zynq SoC to process a CAD model into a series of two-dimensional images to be projected onto a spinning helicoid surface using DLP technology. The SoC contained a combination of custom logic on FPGA fabric as well as software on an embedded processor to implement the unique system functionality

A bioprinted 3D gut model with crypt-villus structures to mimic the intestinal epithelial-stromal microenvironment

The intestine is a complex tissue with a characteristic three-dimensional (3D) crypt-villus architecture, which plays a key role in the intestinal function. This function is also regulated by the intestinal stroma that actively supports the intestinal epithelium, maintaining the homeostasis of the tissue. Efforts to account for the 3D complex structure of the intestinal tissue have been focused mainly in mimicking the epithelial barrier, while solutions to include the stromal compartment are scarce and unpractical to be used in routine experiments. Here we demonstrate that by employing an optimized bioink formulation and the suitable printing parameters it is possible to produce fibroblast-laden crypt-villus structures by means of digital light projection stereolithography (DLP-SLA). This process provides excellent cell viability, accurate spatial resolution, and high printing throughput, resulting in a robust biofabrication approach that yields functional gut mucosa tissues compatible with conventional testing techniques.Copyright © 2023 Elsevier B.V. All rights reserved

Optimisation of CT protocols for cardiac imaging using three-dimensional printing technology

Objective: This thesis investigates the application of 3D-printing technology for optimising coronary CT angiography (CCTA) protocols using iterative reconstruction (IR) as a dose optimisation strategy. Methods: In phase one, a novel 3D-printed cardiac insert phantom for the Lungman phantom was developed. The attenuation values of the printed phantom were compared to CCTA patients and Catphan® 500 images. In phase two, the printed phantom was scanned at multiple dose levels, and the datasets were reconstructed using different IR strengths. The image quality characteristics were measured to determine the dose reduction potential. In phase three, the influence of IR strengths with low-tube voltage for dose optimisation studies was investigated. The printed phantom and the Catphan® 500 were scanned at different tube currents and voltages. The results were compared to the patient datasets to measure the agreement between the phantoms and patient datasets. Results: In phase one, the attenuation values were consistent between the printed phantom, patient and Catphan® 500 images. In phase two, the results showed that decreasing dose levels had significantly increased the image noise (p<0.001). The application of various IR strengths had yielded a stepwise improvement of noise image quality with a dose reduction potential of up to 40%. In phase three, the results showed a significant interaction between the effects of low-tube voltage and the IR strengths on image quality (all p<0.001) but not the attenuation values. The mean differences were small between the patient-phantom datasets. The optimised CT protocols allowed up to 57% dose reduction in CCTA protocols while maintaining the image quality. Conclusions: The 3D-printed cardiac insert phantom can be used to evaluate the effect of using IR on dose reduction and image quality. This thesis proposes and validates a new method of developing phantoms for CCTA dose optimisation studies

Verification of Unstructured Grid Adaptation Components

Adaptive unstructured grid techniques have made limited impact on production analysis workflows where the control of discretization error is critical to obtaining reliable simulation results. Recent progress has matured a number of independent implementations of flow solvers, error estimation methods, and anisotropic grid adaptation mechanics. Known differences and previously unknown differences in grid adaptation components and their integrated processes are identified here for study. Unstructured grid adaptation tools are verified using analytic functions and the Code Comparison Principle. Three analytic functions with different smoothness properties are adapted to show the impact of smoothness on implementation differences. A scalar advection-diffusion problem with an analytic solution that models a boundary layer is adapted to test individual grid adaptation components. Laminar flow over a delta wing and turbulent flow over an ONERA M6 wing are verified with multiple, independent grid adaptation procedures to show consistent convergence to fine-grid forces and a moment. The scalar problems illustrate known differences in a grid adaptation component implementation and a previously unknown interaction between components. The wing adaptation cases in the current study document a clear improvement to existing grid adaptation procedures. The stage is set for the infusion of verified grid adaptation into production fluid flow simulations

Stereolithography

The stereolithography (SLA) process and its methods are introduced in this chapter. After establishing SLA as pertaining to the high-resolution but also high-cost spectrum of the 3D printing technologies, different classifications of SLA processes are presented. Laser-based SLA and digital light processing (DLP), as well as their specialized techniques such as two-photon polymerization (TPP) or continuous liquid interface production (CLIP) are discussed and analyzed for their advantages and shortcomings. Prerequisites of SLA resins and the most common resin compositions are discussed. Furthermore, printable materials and their applications are briefly reviewed, and insight into commercially available SLA systems is given. Finally, an outlook highlighting challenges within the SLA process and propositions to resolve these are offered

A comparison of the Fitting Surface Trueness and Precision of Traditionally Constructed Complete Dentures and 3D Printed Dentures

Introduction: Complete denture construction was revolutionised in the 1930’s when (Polymethyl Methacrylate) PMMA was developed. But it does have its drawbacks. This research compared the fitting surface trueness and precision of complete dentures against the fitting surface trueness and precision of new 3D printed dentures using additive manufacturing techniques. Method: 10 sets of both traditional and 3-D printed dentures were constructed and assessed. Virtual digital dentures were created using scans of the master casts and try-ins from the traditional workflow. The teeth on the virtual dentures were digitally removed to produce printable denture blanks with tooth sockets. The blanks were printed. Commercially available teeth were re-inserted into the blanks. Post-print curing was completed in a light box. Scans of traditional and printed dentures were taken at each stage of production and measured for trueness and precision against the model scans. Results: Paired t-tests (p≤0.05) were conducted on traditional dentures and compared against printed baseplates without and with teeth. Means and signed standard deviations distances were calculated. Mean deviations were 0.055 +/- 0.008mm for upper traditional dentures and 0.061 +/- 0.075 mm for lowers. Printed mean deviations for upper and lower dentures measured 0.109 +/- 0.007 mm and 0.076 +/- 0.013mm. P values for upper trueness was calculated at (p= 0.000) and precision p value measured (p= 0.000). For lowers trueness p value was measured at (p= 0.006) and precision p value measured (p=0.006). Conclusion: Traditionally constructed dentures were significantly more accurate than printed dentures. The results for printing were promising. When printed, lowers were more accurate than traditionally constructed dentures until teeth were added. Light curing and storage of baseplates prior to adding teeth may be a factor in determining trueness and precision. Further work investigating storage of light cured dentures is needed as this may affect denture trueness and precision