Deep Shading: Convolutional Neural Networks for Screen-Space Shading

In computer vision, Convolutional Neural Networks (CNNs) have recently achieved new levels of performance for several inverse problems where RGB pixel appearance is mapped to attributes such as positions, normals or reflectance. In computer graphics, screen-space shading has recently increased the visual quality in interactive image synthesis, where per-pixel attributes such as positions, normals or reflectance of a virtual 3D scene are converted into RGB pixel appearance, enabling effects like ambient occlusion, indirect light, scattering, depth-of-field, motion blur, or anti-aliasing. In this paper we consider the diagonal problem: synthesizing appearance from given per-pixel attributes using a CNN. The resulting Deep Shading simulates all screen-space effects as well as arbitrary combinations thereof at competitive quality and speed while not being programmed by human experts but learned from example images

Deep Mid-Infrared Silicate Absorption as a Diagnostic of Obscuring Geometry Toward Galactic Nuclei

The silicate cross section peak near 10um produces emission and absorption features in the spectra of dusty galactic nuclei observed with the Spitzer Space Telescope. Especially in ultraluminous infrared galaxies, the observed absorption feature can be extremely deep, as IRAS 08572+3915 illustrates. A foreground screen of obscuration cannot reproduce this observed feature, even at large optical depth. Instead, the deep absorption requires a nuclear source to be deeply embedded in a smooth distribution of material that is both geometrically and optically thick. In contrast, a clumpy medium can produce only shallow absorption or emission, which are characteristic of optically-identified active galactic nuclei. In general, the geometry of the dusty region and the total optical depth, rather than the grain composition or heating spectrum, determine the silicate feature's observable properties. The apparent optical depth calculated from the ratio of line to continuum emission generally fails to accurately measure the true optical depth. The obscuring geometry, not the nature of the embedded source, also determines the far-IR spectral shape.Comment: To appear in ApJ

Mixed Reality Architecture: a dynamic architectural topology

Architecture can be shown to structure patterns of co-presence and in turn to be structured itself by the rules and norms of the society present within it. This two-way relationship exists in a surprisingly stable framework, as fundamental changes to buildings are slow and costly. At the same time, change within organisations is increasingly rapid and buildings are used to accommodate some of that change. This adaptation can be supported by the use of telecommunication technologies, overcoming the need for co-presence during social interaction. However, often this results in a loss of accountability or ‘civic legibility’, as the link between physical location and social activity is broken. In response to these considerations, Mixed Reality Architecture (MRA) was developed. MRA links multiple physical spaces across a shared 3D virtual world. We report on the design of MRA, including the key concept of the Mixed Reality Architectural Cell, a novel architectural interface between architectural spaces that are remote to each other. An in-depth study lasting one year and involving six office-based MRACells, used video recordings, the analysis of event logs, diaries and an interview survey. This produced a series of ethnographic vignettes describing social interaction within MRA in detail. In this paper we concentrate on the topological properties of MRA. It can be shown that the dynamic topology of MRA and social interaction taking place within it are fundamentally intertwined. We discuss how topological adjacencies across virtual space change the integration of the architectural spaces that MRA is installed in. We further reflect on how the placement of MRA technology in different parts of an office space (deep or shallow) impacts on the nature of that particular space. Both the above can be shown to influence movement through the building and social interaction taking place within it. These findings are directly relevant to new buildings that need to be designed to accommodate organisational change in future but also to existing building stock that might be very hard to adapt. We are currently expanding the system to new sites and are planning changes to the infrastructure of MRA as well as its interactional interface

Diapycnal oxygen supply to the tropical North Atlantic oxygen minimum zone

The replenishment of consumed oxygen in the open ocean oxygen minimum zone (OMZ) off northwest Africa is accomplished by oxygen transport across and along density surfaces, i.e. diapycnal and isopycnal oxygen supply. Here the diapycnal oxygen supply is investigated using a large observational set of oxygen profiles and diapycnal mixing data from years 2008 to 2010. Diapycnal mixing is inferred from different sources: (i) a large-scale tracer release experiment, (ii) microstructure profiles, and (iii) shipboard acoustic current measurements plus density profiles. From these measurements, the average diapycnal diffusivity in the studied depth interval from 150 to 500m is estimated to be 1×10−5 m2 s−1, with lower and upper 95%confidence limits of 0.8×10−5 m2 s−1 and 1.4×10−5 m2 s−1. Diapycnal diffusivity in this depth range is predominantly caused by turbulence, and shows no significant vertical gradient. Diapycnal mixing is found to contribute substantially to the oxygen supply of the OMZ. Within the OMZ core, 1.5 μmol kg−1 yr−1 of oxygen is supplied via diapycnal mixing, contributing about one-third of the total demand. This oxygen which is supplied via diapycnal mixing originates from oxygen that has been laterally supplied within the upper CentralWater layer above the OMZ, and within the Antarctic Intermediate Water layer below the OMZ. Due to the existence of a separate shallow oxygen minimum at about 100m depth throughout most of the study area, there is no net vertical oxygen flux from the surface layer into the Central Water layer. Thus all oxygen supply of the OMZ is associated with remote pathways

Conceptualizing Thought-Forms Through Dynamic Artworks

This summer research project was focused on creating a new body of abstract artwork inspired by the thought-forms conceptualized through the Theosophy movement and its impact on abstract artists in the early 20th century. By exploring the works of Hilma af Klint and Wassily Kandinsky, I gained a deep appreciation for the role spirituality can play in art. I also explored the significance of color theories and applied them to my work. The artwork I created focuses on the interaction of color and form and movement within 2-dimensional space through the mediums of screen printing and hand marbling