Rain rendering for evaluating and improving robustness to bad weather

Rain fills the atmosphere with water particles, which breaks the common assumption that light travels unaltered from the scene to the camera. While it is well-known that rain affects computer vision algorithms, quantifying its impact is difficult. In this context, we present a rain rendering pipeline that enables the systematic evaluation of common computer vision algorithms to controlled amounts of rain. We present three different ways to add synthetic rain to existing images datasets: completely physic-based; completely data-driven; and a combination of both. The physic-based rain augmentation combines a physical particle simulator and accurate rain photometric modeling. We validate our rendering methods with a user study, demonstrating our rain is judged as much as 73% more realistic than the state-of-theart. Using our generated rain-augmented KITTI, Cityscapes, and nuScenes datasets, we conduct a thorough evaluation of object detection, semantic segmentation, and depth estimation algorithms and show that their performance decreases in degraded weather, on the order of 15% for object detection, 60% for semantic segmentation, and 6-fold increase in depth estimation error. Finetuning on our augmented synthetic data results in improvements of 21% on object detection, 37% on semantic segmentation, and 8% on depth estimation.Comment: 19 pages, 19 figures, IJCV 2020 preprint. arXiv admin note: text overlap with arXiv:1908.1033

Text Similarity Between Concepts Extracted from Source Code and Documentation

Context: Constant evolution in software systems often results in its documentation losing sync with the content of the source code. The traceability research field has often helped in the past with the aim to recover links between code and documentation, when the two fell out of sync. Objective: The aim of this paper is to compare the concepts contained within the source code of a system with those extracted from its documentation, in order to detect how similar these two sets are. If vastly different, the difference between the two sets might indicate a considerable ageing of the documentation, and a need to update it. Methods: In this paper we reduce the source code of 50 software systems to a set of key terms, each containing the concepts of one of the systems sampled. At the same time, we reduce the documentation of each system to another set of key terms. We then use four different approaches for set comparison to detect how the sets are similar. Results: Using the well known Jaccard index as the benchmark for the comparisons, we have discovered that the cosine distance has excellent comparative powers, and depending on the pre-training of the machine learning model. In particular, the SpaCy and the FastText embeddings offer up to 80% and 90% similarity scores. Conclusion: For most of the sampled systems, the source code and the documentation tend to contain very similar concepts. Given the accuracy for one pre-trained model (e.g., FastText), it becomes also evident that a few systems show a measurable drift between the concepts contained in the documentation and in the source code.</p

MESSENGER Observations of Volcanism on Mercury: From Hokusai Quadrangle Down to Small Cones

This thesis addresses the regional geology of the planet Mercury as seen by the MErcury Surface, Space ENvironment, and Ranging (MESSENGER) mission. I aimed to investigate the existence and origin of volcanic photogeological units and landforms on Mercury not mappable at the global scale. Using MESSENGER images, I have made the first 1:3,000,000-scale geological map of the Hokusai (H05) quadrangle. My map shows that this region has a similar history of effusive volcanism to the rest of Mercury, with widespread plains formation having given way to lower volume effusions that were ultimately confined to impact craters. However, I found that H05 contains plains that do not conform to the definitions of the two globally recognised plains units on Mercury, intercrater plains and smooth plains, which are thought to be volcanic in origin. I mapped such plains as intermediate plains, due to their intermediate roughness between the two global plains types, and I suggest that they represent incompletely volcanically resurfaced regions of Mercury’s crust. The apparent absence of even small volcanic constructs on Mercury, emphasised to me during my mapping of the volcanologically diverse H05, led me to search for such constructs across Mercury. The two candidates I found, if volcanic, were probably built by low-volume eruptions that were uncharacteristic of most of Mercury’s volcanic history. During my search for volcanoes, I investigated the circum-Caloris knobs. Through mapping, photogeological observations and topographic measurements, I have shown that these small (<15 km across) landforms are not volcanoes, but instead are Caloris ejecta blocks that have undergone long-lived, or even recent, modification into cones. My observations suggest that volatile-loss might have driven modification of the blocks. The intermediate plains, candidate volcanoes, and circum-Caloris knobs will be important targets for the BepiColombo mission, which launched during the preparation of this thesis

Tracking the Temporal-Evolution of Supernova Bubbles in Numerical Simulations

The study of low-dimensional, noisy manifolds embedded in a higher dimensional space has been extremely useful in many applications, from the chemical analysis of multi-phase flows to simulations of galactic mergers. Building a probabilistic model of the manifolds has helped in describing their essential properties and how they vary in space. However, when the manifold is evolving through time, a joint spatio-temporal modelling is needed, in order to fully comprehend its nature. We propose a first-order Markovian process that propagates the spatial probabilistic model of a manifold at fixed time, to its adjacent temporal stages. The proposed methodology is demonstrated using a particle simulation of an interacting dwarf galaxy to describe the evolution of a cavity generated by a Supernov

Producing airspace : the contested geographies of Nottingham East Midlands Airport

During the last 100 years, commercial aviation has developed into an established mode of transportation serving millions of passengers every year, but while researchers from other disciplines - most notably sociology, cultui-al history, and anthropology - have begun to appreciate the multiple dimensions of flight, geographers have written surprisingly little on the subject beyond quantitative analyses of airline networks. While perhaps understandable given the present geopolitical climate of passenger (in)security and commercial confidentiality, this nevertheless means many of the industry's significant facets have yet to be adequately charted. Considering geography's rich heritage of examining space, place, and spatial phenomena at a variety of scales, this thesis provides a distinctive contribution to theoretical and empirical knowledge by addressing the multiple geographies of airspace. Set in the context of the ongoing controversy surrounding the reorganisation offlightpaths at Nottingham East Midlands Airport (NEMA) in the United Kingdom, it considers the inherently geographical and often contested nature of airspace production. By detailing the complex interplay between how airspace is produced 'on the ground' by those who oppose its use, and 'in the air' by Air Traffic Controllers and airline pilots, it offers a new perspective for studies of geography and air transport in an age of mass aeromobility.EThOS - Electronic Theses Online ServiceGBUnited Kingdo