7,401 research outputs found
A HoloLens Framework for Augmented Reality Applications in Breast Cancer Surgery
This project aims to support oncologic breast-conserving surgery by creating a platform for better surgical planning through the development of a framework that is capable of displaying a virtual model of the tumour(s) requiring surgery, on a patient's breast. Breast-conserving surgery is the first clear option when it comes to tackling cases of breast cancer, but the surgery comes with risks. The surgeon wants to maintain clean margins while performing the procedure such that the disease does not resurface. This calls for the importance of surgical planning where the surgeon consults with radiologists and pre-surgical imaging such as Magnetic Resonance Imaging (MRI). The MRI prior to the surgical procedure, however, is taken with the patient in the prone position (face-down) but the surgery happens in a supine position (face-up). Thus mapping the location of the tumour(s) to the corresponding anatomical position from the MRI is a tedious task which requires a large amount of expertise and time given that the organ is soft and flexible.
For this project, the tumour is visualized in the corresponding anatomical position to assist in surgical planning. Augmented Reality is the best option for this problem and this, in turn, led to an investigation of the application capability of the Microsoft HoloLens to solve this problem. Given its multitude of sensors and resolution of display the device is a fine candidate for this process. However, the HoloLens is still under development with a large number of limitations in its use. This work tries to compensate for these limitations using the existing hardware and software in the device's arsenal.
Within this masters thesis, the principal questions answered are related to the acquiring of data from breast mimicking objects in acceptable resolutions, discriminating between the information based on photometry, offloading the data to a computer for post-processing in creating a correspondence between the MRI data and acquired data, and finally retrieving the processed information such that the MRI information can be used for visualizing the tumor in the anatomically precise position. Unfortunately, time limitations for this project led to an incomplete system which is not completely synchronized, however, our work has solidified the grounds for the software aspects toward the final goals set out such that extensive exploration need only be done in the imaging side of this problem
New techniques for the scientific visualization of three-dimensional multi-variate and vector fields
Slice and Dice: A Physicalization Workflow for Anatomical Edutainment
During the last decades, anatomy has become an interesting topic in
education---even for laymen or schoolchildren. As medical imaging techniques
become increasingly sophisticated, virtual anatomical education applications
have emerged. Still, anatomical models are often preferred, as they facilitate
3D localization of anatomical structures. Recently, data physicalizations
(i.e., physical visualizations) have proven to be effective and
engaging---sometimes, even more than their virtual counterparts. So far,
medical data physicalizations involve mainly 3D printing, which is still
expensive and cumbersome. We investigate alternative forms of physicalizations,
which use readily available technologies (home printers) and inexpensive
materials (paper or semi-transparent films) to generate crafts for anatomical
edutainment. To the best of our knowledge, this is the first computer-generated
crafting approach within an anatomical edutainment context. Our approach
follows a cost-effective, simple, and easy-to-employ workflow, resulting in
assemblable data sculptures (i.e., semi-transparent sliceforms). It primarily
supports volumetric data (such as CT or MRI), but mesh data can also be
imported. An octree slices the imported volume and an optimization step
simplifies the slice configuration, proposing the optimal order for easy
assembly. A packing algorithm places the resulting slices with their labels,
annotations, and assembly instructions on a paper or transparent film of
user-selected size, to be printed, assembled into a sliceform, and explored. We
conducted two user studies to assess our approach, demonstrating that it is an
initial positive step towards the successful creation of interactive and
engaging anatomical physicalizations
Flame front propagation velocity measurement and in-cylinder combustion reconstruction using POET
The objective of this thesis is to develop an intelligent diagnostic technique
POET (Passive Optical Emission Tomography) for the investigation of in cylinder
combustion chemiluminescence. As a non-intrusive optical system, the POET system
employs 40 fibre optic cables connected to 40 PMTs (Photo Multiplier Tube) to
monitor the combustion process and flame front propagation in a modified commercial
OHV (Over Head Valve) Pro 206 IC engine.
The POET approach overcomes several limitations of present combustion
research methods using a combination of fibre optic detection probes, photomultipliers
and a tomographic diagnostics. The fibre optic probes are placed on a specially
designed cylinder head gasket for non-invasively inserting cylinder. Each independent
probe can measure the turbulent chemiluminescence of combustion flame front at up to
20 kHz. The resultant intensities can then be gathered tomographically using MART
(Multiplicative Algebraic Reconstruction Technique) software to reconstruct an image
of the complete flame-front. The approach is essentially a lensless imaging technique,
which has the advantage of not requiring a specialized engine construction with
conventional viewing ports to visualize the combustion image. The fibre optic system,
through the use of 40, 2m long thermally isolated fibre optic cables can withstand
combustion temperatures and is immune from electronic noise, typically generated by
the spark plug.
The POET system uses a MART tomographic methodology to reconstruct the turbulent combustion process. The data collected has been reconstructed to produce a
temporal and spatial image of the combustion flame front. The variations of lame
turbulence are monitored by sequences of reconstructed images. Therefore, the POET
diagnostic technique reduces the complications of classic flame front propagation
measurement systems and successfully demonstrates the in-cylinder combustion
process.
In this thesis, a series of calibration exercises have been performed to ensure
that the photomultipliers of the POET system have sufficient temporal and spatial
resolution to quantitatively map the flow velocity turbulence and chemiluminescence
of the flame front. In the results, the flame has been analyzed using UV filters and blue
filters to monitor the modified natural gas fuel engine. The flame front propagation
speed has been evaluated and it is, on average, 12 m/s at 2280 rpm. Sequences of
images have been used to illustrate the combustion explosion process at different rpm
Revealing the Invisible: On the Extraction of Latent Information from Generalized Image Data
The desire to reveal the invisible in order to explain the world around us has been a source of impetus for technological and scientific progress throughout human history. Many of the phenomena that directly affect us cannot be sufficiently explained based on the observations using our primary senses alone. Often this is because their originating cause is either too small, too far away, or in other ways obstructed. To put it in other words: it is invisible to us. Without careful observation and experimentation, our models of the world remain inaccurate and research has to be conducted in order to improve our understanding of even the most basic effects. In this thesis, we1 are going to present our solutions to three challenging problems in visual computing, where a surprising amount of information is hidden in generalized image data and cannot easily be extracted by human observation or existing methods. We are able to extract the latent information using non-linear and discrete optimization methods based on physically motivated models and computer graphics methodology, such as ray tracing, real-time transient rendering, and image-based rendering
NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 40)
Abstracts are provided for 181 patents and patent applications entered into the NASA scientific and technical information system during the period July 1991 through December 1991. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application
Reconsidering light transport : acquisition and display of real-world reflectance and geometry
In this thesis, we cover three scenarios that violate common simplifying assumptions about the nature of light transport. We begin with the first ingredient to any çD rendering: a geometry model. Most çD scanners require the object-of-interest to show diffuse refectance. The further a material deviates from the Lambertian model, the more likely these setups are to produce corrupted results. By placing a traditional laser scanning setup in a participating (in particular, fuorescent) medium, we have built a light sheet scanner that delivers robust results for a wide range of materials, including glass. Further investigating the phenomenon of fluorescence, we notice that, despite its ubiquity, it has received moderate attention in computer graphics. In particular, to date no datadriven reflectance models of fluorescent materials have been available. To describe the wavelength-shifling reflectance of fluorescent materials, we define the bispectral bidirectional reflectance and reradiation distribution function (BRRDF), for which we introduce an image-based measurement setup as well as an efficient acquisition scheme. Finally, we envision a computer display that showsmaterials instead of colours, and present a prototypical device that can exhibit anisotropic reflectance distributions similar to common models in computer graphics.In der Computergraphik und Computervision ist es unerlässlich, vereinfachende Annahmen über die Ausbreitung von Licht zumachen. In dieser Dissertation stellen wir drei Fälle vor, in denen diese nicht zutreffen. So wird die dreidimensionale Geometrie von Gegenständen oft mit Hilfe von Laserscannern vermessen und dabei davon ausgegangen, dass ihre Oberfläche diffus reflektiert. Dies ist bei den meisten Materialien jedoch nicht gegeben, so dass die Ergebnisse oft fehlerhaft sind. Indem wir das Objekt in einem fluoreszierenden Medium einbetten, kann ein klassischer CD-Scanner-Aufbau so modifiziert werden, dass er verlässliche Geometriedaten für Objekte aus verschiedensten Materialien liefert, einschließlich Glas. Auch die akkurate Nachbildung des Aussehens von Materialien ist wichtig für die photorealistische Bildsynthese. Wieder interessieren wir uns für Fluoreszenz, diesmal allerdings für ihr charakteristisches Erscheinungsbild, das in der Computergraphik bislang kaum Beachtung gefunden hat. Wir stellen einen bildbasierten Aufbau vor, mit dem die winkel- und wellenlängenabhängige Reflektanz fluoreszierender Oberflächen ausgemessen werden kann, und eine Strategie, um solche Messungen effizient abzuwickeln. Schließlich befassen wir uns mit der Idee, nicht nur Farben dynamisch anzuzeigen, sondern auch Materialien und ihr je nach Lichteinfall und Blickwinkel unterschiedliches Aussehen. Einer generellen Beschreibung des Problems folgt die konkrete Umsetzung in Formzweier Prototypen, die verschiedene Reflektanzverteilungen auf einer Oberfläche darstellen können
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