Classic Mosaics and Visual Correspondence via Graph-Cut based Energy Optimization

Computer graphics and computer vision were traditionally two distinct research fields focusing on opposite topics. Lately, they have been increasingly borrowing ideas and tools from each other. In this thesis, we investigate two problems in computer vision and graphics that rely on the same tool, namely energy optimization with graph cuts. In the area of computer graphics, we address the problem of generating artificial classic mosaics, still and animated. The main purpose of artificial mosaics is to help a user to create digital art. First we reformulate our previous static mosaic work in a more principled global optimization framework. Then, relying on our still mosaic algorithm, we develop a method for producing animated mosaics directly from real video sequences, which is the first such method, we believe. Our mosaic animation style is uniquely expressive. Our method estimates the motion of the pixels in the video, renders the frames with mosaic effect based on both the colour and motion information from the input video. This algorithm relies extensively on our novel motion segmentation approach, which is a computer vision problem. To improve the quality of our animated mosaics, we need to improve the motion segmentation algorithm. Since motion and stereo problems have a similar setup, we start with the problem of finding visual correspondence for stereo, which has the advantage of having datasets with ground truth, useful for evaluation. Most previous methods for stereo correspondence do not provide any measure of reliability in their estimates. We aim to find the regions for which correspondence can be determined reliably. Our main idea is to find corresponding regions that have a sufficiently strong texture cue on the boundary, since texture is a reliable cue for matching. Unlike the previous work, we allow the disparity range within each such region to vary smoothly, instead of being constant. This produces blob-like semi-dense visual features for which we have a high confidence in their estimated ranges of disparities

Complexity of monodic guarded fragments over linear and real time

Accepted versio

SN 2015U: A Rapidly Evolving and Luminous Type Ibn Supernova

Supernova (SN) 2015U (also known as PSN J07285387+3349106) was discovered in NGC 2388 on 2015 Feb. 11. A rapidly evolving and luminous event, it showed effectively hydrogen-free spectra dominated by relatively narrow helium P-Cygni spectral features and it was classified as a SN Ibn. In this paper we present photometric, spectroscopic, and spectropolarimetric observations of SN 2015U, including a Keck/DEIMOS spectrum (resolution $\approx$ 5000) which fully resolves the optical emission and absorption features. We find that SN 2015U is best understood via models of shock breakout from extended and dense circumstellar material (CSM), likely created by a history of mass loss from the progenitor with an extreme outburst within $\sim$1-2 yr of core collapse (but we do not detect any outburst in our archival imaging of NGC 2388). We argue that the high luminosity of SN 2015U was powered not through $^{56}$Ni decay but via the deposition of kinetic energy into the ejecta/CSM shock interface. Though our analysis is hampered by strong host-galaxy dust obscuration (which likely exhibits multiple components), our dataset makes SN 2015U one of the best-studied Type Ibn supernovae and provides a bridge of understanding to other rapidly fading transients, both luminous and relatively faint.Comment: 20 pages, 15 figures, 4 table

Decidability and complexity via mosaics of the temporal logic of the lexicographic products of unbounded dense linear orders

This article considers the temporal logic of the lexicographic products of unbounded dense linear orders and provides via mosaics a complete decision procedure in nondeterministic polynomial time for the satisfiability problem it gives rise to

A Quaint & Curious Volume

John J. Dobbins, Professor of Roman Art and Archaeology, taught at the University of Virginia in the Department of Art from 1978 until his retirement in 2019. His legacy of research and pedagogy is explored in <i>A Quaint & Curious Volume: Essays in Honor of John J. Dobbins</i>. Professor Dobbins’ research in the field of Roman art and archaeology spans the geographical and chronological limits of the Roman Empire, from Pompeii to Syria, and Etruria to Spain. This volume demonstrates some of his wide-reaching interests, expressed through the research of his former graduate students. Several essays examine the city of Pompeii and cover the topics of masonry analysis, re-examinations of streets and drains, and analyses of the heating capacity of baths in Pompeii. Beyond Pompeii, the archaeological remains of bakeries are employed to elucidate labor specialization in the Late Roman period across the Mediterranean basin. Collaborations between Professor Dobbins and his former students are also explored, including a pioneering online numismatic database and close examination of sculpture and mosaics, including expressions of identity and patronage through case studies of the Ara Pacis and mosaics at Antioch-on-the-Orontes. <i>A Quaint & Curious Volume </i>not only demonstrates John Dobbins’ scholarly legacy, but also presents new readings of archaeological data and art, illustrating the impact that one professor can have on the wider field of Roman art and archaeology through the continuing work of his students