The standard plenoptic camera: applications of a geometrical light field model

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of PhilosophyThe plenoptic camera is an emerging technology in computer vision able to capture a light field image from a single exposure which allows a computational change of the perspective view just as the optical focus, known as refocusing. Until now there was no general method to pinpoint object planes that have been brought to focus or stereo baselines of perspective views posed by a plenoptic camera. Previous research has presented simplified ray models to prove the concept of refocusing and to enhance image and depth map qualities, but lacked promising distance estimates and an efficient refocusing hardware implementation. In this thesis, a pair of light rays is treated as a system of linear functions whose solution yields ray intersections indicating distances to refocused object planes or positions of virtual cameras that project perspective views. A refocusing image synthesis is derived from the proposed ray model and further developed to an array of switch-controlled semi-systolic FIR convolution filters. Their real-time performance is verified through simulation and implementation by means of an FPGA using VHDL programming. A series of experiments is carried out with different lenses and focus settings, where prediction results are compared with those of a real ray simulation tool and processed light field photographs for which a blur metric has been considered. Predictions accurately match measurements in light field photographs and signify deviations of less than 0.35 % in real ray simulation. A benchmark assessment of the proposed refocusing hardware implementation suggests a computation time speed-up of 99.91 % in comparison with a state-of-the-art technique. It is expected that this research supports in the prototyping stage of plenoptic cameras and microscopes as it helps specifying depth sampling planes, thus localising objects and provides a power-efficient refocusing hardware design for full-video applications as in broadcasting or motion picture arts

The Millennium Run Observatory: First Light

Simulations of galaxy evolution aim to capture our current understanding as well as to make predictions for testing by future experiments. Simulations and observations are often compared in an indirect fashion: physical quantities are estimated from the data and compared to models. However, many applications can benefit from a more direct approach, where the observing process is also simulated and the models are seen fully from the observer's perspective. To facilitate this, we have developed the Millennium Run Observatory (MRObs), a theoretical virtual observatory which uses virtual telescopes to `observe' semi-analytic galaxy formation models based on the suite of Millennium Run dark matter simulations. The MRObs produces data that can be processed and analyzed using the standard software packages developed for real observations. At present, we produce images in forty filters from the rest-frame UV to IR for two stellar population synthesis models, three different models of IGM absorption, and two cosmologies (WMAP1/7). Galaxy distributions for a large number of mock lightcones can be `observed' using models of major ground- and space-based telescopes. The data include lightcone catalogues linked to structural properties of galaxies, pre-observation model images, mock telescope images, and Source Extractor products that can all be traced back to the higher level dark matter, semi-analytic galaxy, and lightcone catalogues available in the Millennium database. Here, we describe our methods and announce a first public release of simulated surveys (e.g., SDSS, CFHT-LS, GOODS, GOODS/ERS, CANDELS, and HUDF). The MRObs browser, an online tool, further facilitates exploration of the simulated data. We demonstrate the benefits of a direct approach through a number of example applications (galaxy number counts in CANDELS, clusters, morphologies, and dropout selections).Comment: MNRAS, in press. Millennium Run Observatory data products, online tools, and more available through http://galformod.mpa-garching.mpg.de/mrobs