Recent advances in optical tomography in low scattering media

Low scattering media is the best scenario for optical imaging in thick samples and deep tissue, as it allows to obtain high resolution images without suffering the limitations that the diffusion phenomenon imposes. The high contribution of ballistic light in this regime enabled the development of light sheet microscopy and optical projection tomography, two of the most common techniques nowadays in research laboratories. Their revolutionary approach and wide spectrum of applications and possibilities has lead to a frenetic rhythm of new works and techniques arising every year. The large amount of information available often overwhelms scientists and researchers trying to keep up to date with the last cutting edge advances of the field. This paper aims to give a brief review of the origins and fundamental aspects of these two techniques to focus on the most recent and yet non reviewed works. Apart from novel methods, this document also covers combined multimodal approaches and systems. To conclude, we put a spotlight on the important role that open-source microscopy systems play in the field, as they improve the accessibility to these techniques and promote collaborative networks across the optical imaging community

Material Recognition Meets 3D Reconstruction : Novel Tools for Efficient, Automatic Acquisition Systems

For decades, the accurate acquisition of geometry and reflectance properties has represented one of the major objectives in computer vision and computer graphics with many applications in industry, entertainment and cultural heritage. Reproducing even the finest details of surface geometry and surface reflectance has become a ubiquitous prerequisite in visual prototyping, advertisement or digital preservation of objects. However, today's acquisition methods are typically designed for only a rather small range of material types. Furthermore, there is still a lack of accurate reconstruction methods for objects with a more complex surface reflectance behavior beyond diffuse reflectance. In addition to accurate acquisition techniques, the demand for creating large quantities of digital contents also pushes the focus towards fully automatic and highly efficient solutions that allow for masses of objects to be acquired as fast as possible. This thesis is dedicated to the investigation of basic components that allow an efficient, automatic acquisition process. We argue that such an efficient, automatic acquisition can be realized when material recognition "meets" 3D reconstruction and we will demonstrate that reliably recognizing the materials of the considered object allows a more efficient geometry acquisition. Therefore, the main objectives of this thesis are given by the development of novel, robust geometry acquisition techniques for surface materials beyond diffuse surface reflectance, and the development of novel, robust techniques for material recognition. In the context of 3D geometry acquisition, we introduce an improvement of structured light systems, which are capable of robustly acquiring objects ranging from diffuse surface reflectance to even specular surface reflectance with a sufficient diffuse component. We demonstrate that the resolution of the reconstruction can be increased significantly for multi-camera, multi-projector structured light systems by using overlappings of patterns that have been projected under different projector poses. As the reconstructions obtained by applying such triangulation-based techniques still contain high-frequency noise due to inaccurately localized correspondences established for images acquired under different viewpoints, we furthermore introduce a novel geometry acquisition technique that complements the structured light system with additional photometric normals and results in significantly more accurate reconstructions. In addition, we also present a novel method to acquire the 3D shape of mirroring objects with complex surface geometry. The aforementioned investigations on 3D reconstruction are accompanied by the development of novel tools for reliable material recognition which can be used in an initial step to recognize the present surface materials and, hence, to efficiently select the subsequently applied appropriate acquisition techniques based on these classified materials. In the scope of this thesis, we therefore focus on material recognition for scenarios with controlled illumination as given in lab environments as well as scenarios with natural illumination that are given in photographs of typical daily life scenes. Finally, based on the techniques developed in this thesis, we provide novel concepts towards efficient, automatic acquisition systems

Commissioning and out-of-field dose characterisation of the Elekta Unity MRL

Marcus Powers commissioned the Southern Hemisphere's first clinical MRI-guided Linear Accelerator and assessed radiation doses during treatments with the machine. He found it was suitable for the provision of cancer therapy and revealed potential unintended radiation deposition to distal patient regions. His discoveries are facilitating safer cancer treatments throughout Australia

COBE's search for structure in the Big Bang

The launch of Cosmic Background Explorer (COBE) and the definition of Earth Observing System (EOS) are two of the major events at NASA-Goddard. The three experiments contained in COBE (Differential Microwave Radiometer (DMR), Far Infrared Absolute Spectrophotometer (FIRAS), and Diffuse Infrared Background Experiment (DIRBE)) are very important in measuring the big bang. DMR measures the isotropy of the cosmic background (direction of the radiation). FIRAS looks at the spectrum over the whole sky, searching for deviations, and DIRBE operates in the infrared part of the spectrum gathering evidence of the earliest galaxy formation. By special techniques, the radiation coming from the solar system will be distinguished from that of extragalactic origin. Unique graphics will be used to represent the temperature of the emitting material. A cosmic event will be modeled of such importance that it will affect cosmological theory for generations to come. EOS will monitor changes in the Earth's geophysics during a whole solar color cycle

Three-Dimensional Digital Recording and Modelling Methodologies for Documentation and Reconstruction of the Newport Medieval Ship

The following thesis presents the three-dimensional digital documentation methods and modelling approaches used during the excavation and post-excavation research phases of the Newport Medieval Ship Project. The primary case study is the Newport Medieval Ship, a large clinker-built merchant vessel discovered in 2002 in Newport, Wales, United Kingdom. The use of accurate and efficient three-dimensional digital recording methodologies has allowed for the development of innovative approaches to organising, analysing, modelling and disseminating data about the individual timbers and the overall original hull form. The utilisation of advanced digital technology and engineering, in the form of Rhinoceros3D modelling software, contact digitising and rapid prototyping has enabled the project to develop and test a variety of new methodologies for documenting and reconstructing ancient vessels. Results of the individual ship timber documentation and modelling methodologies are presented, along with analysis and comparison to more traditional documentation and reconstruction approaches. Additionally, the thesis examines the changing philosophical or conceptual approaches to hull form recording and reconstruction research over the last 200 years, and focuses in detail on the last 20 years of the rapidly evolving field of digital documentation in nautical archaeology