VISUAL SEMANTIC SEGMENTATION AND ITS APPLICATIONS

This dissertation addresses the difficulties of semantic segmentation when dealing with an extensive collection of images and 3D point clouds. Due to the ubiquity of digital cameras that help capture the world around us, as well as the advanced scanning techniques that are able to record 3D replicas of real cities, the sheer amount of visual data available presents many opportunities for both academic research and industrial applications. But the mere quantity of data also poses a tremendous challenge. In particular, the problem of distilling useful information from such a large repository of visual data has attracted ongoing interests in the fields of computer vision and data mining. Structural Semantics are fundamental to understanding both natural and man-made objects. Buildings, for example, are like languages in that they are made up of repeated structures or patterns that can be captured in images. In order to find these recurring patterns in images, I present an unsupervised frequent visual pattern mining approach that goes beyond co-location to identify spatially coherent visual patterns, regardless of their shape, size, locations and orientation. First, my approach categorizes visual items from scale-invariant image primitives with similar appearance using a suite of polynomial-time algorithms that have been designed to identify consistent structural associations among visual items, representing frequent visual patterns. After detecting repetitive image patterns, I use unsupervised and automatic segmentation of the identified patterns to generate more semantically meaningful representations. The underlying assumption is that pixels capturing the same portion of image patterns are visually consistent, while pixels that come from different backdrops are usually inconsistent. I further extend this approach to perform automatic segmentation of foreground objects from an Internet photo collection of landmark locations. New scanning technologies have successfully advanced the digital acquisition of large-scale urban landscapes. In addressing semantic segmentation and reconstruction of this data using LiDAR point clouds and geo-registered images of large-scale residential areas, I develop a complete system that simultaneously uses classification and segmentation methods to first identify different object categories and then apply category-specific reconstruction techniques to create visually pleasing and complete scene models

Sub-Planck structures and sensitivity of the superposed photon-added or photon-subtracted squeezed-vacuum states

The Wigner function of the compass state (a superposition of four coherent states) develops phase-space structures of dimension much less than the Planck scale, which are crucial in determining the sensitivity of these states to phase-space displacements. In the present work, we introduce compass-like states that may have connection to the contemporary experiments, which are obtained by either adding photons to or subtracting photons from the superposition of two squeezed-vacuum states. We show that, when a significant quantity of photons is added (or subtracted), the Wigner function of these states are shown to have phase-space structures of an area that is substantially smaller than the Planck scale. In addition, these states exhibit sensitivity to displacements that is much higher than the standard quantum limit. Finally, we show that both the size of the sub-Planck structures and the sensitivity of our states are strongly influenced by the average photon number, with the photon addition case having a higher average photon number leading to the smaller sub-Planck structures and, consequently, being more sensitive to displacement than the photon subtraction case. Our states offer unprecedented resolution to the external perturbations, making them suitable for quantum sensing applications.Comment: PHYSICAL REVIEW A 107, 052614 (2023), 15 Figures, 20 page

On the Complexity of View Update Analysis and Its Application to Annotation Propagation

This paper investigates three problems identified in [1] for annotation propagation, namely, the view side-effect, source side-effect, and annotation placement problems. Given annotations entered for a tuple or an attribute in a view, these problems ask what tuples or attributes in the source have to be annotated to produce the view annotations. As observed in [1], these problems are fundamental not only for data provenance but also for the management of view updates. For an annotation attached to a single existing tuple in a view, it has been shown that these problems are often intractable even for views defined in terms of simple SPJU queries [1]. We revisit these problems by considering several dichotomies: (1) views defined in various subclasses of SPJU, versus SPJU views under a practical key preserving condition; (2) annotations attached to existing tuples in a view versus annotations on tuples to be inserted into the view; and (3) a single-tuple annotation versus a group of annotations. We provide a complete picture of intractability and tractability for the three problems in all these settings. We show that key preserving views often simplify the propagation analysis. Indeed, some problems become tractable for certain key preserving views, as opposed to the intractability of their counterparts that are not key preserving. However, group annotations often make the analysis harder. In addition, the problems have quite diverse complexity when annotations are attached to existing tuples in a view and when they are entered for tuples to be inserted into the view

Recent advances on thermal analysis of stretchable electronics

Stretchable electronics, which offers the performance of conventional wafer-based devices and mechanical properties of a rubber band, enables many novel applications that are not possible through conventional electronics due to its brittle nature. One effective strategy to realize stretchable electronics is to design the inorganic semiconductor material in a stretchable format on a compliant elastomeric substrate. Engineering thermal management is essential for the development of stretchable electronics to avoid adverse thermal effects on its performance as well as in applications involving human body and biological tissues where even 1–2 °C temperature increase is not allowed. This article reviews the recent advances in thermal management of stretchable inorganic electronics with focuses on the thermal models and their comparisons to experiments and finite element simulations

A three-terminal heat engine based on resonant-tunneling multi-level quantum dots

A three-terminal heat engine based on resonant-tunneling multi-level quantum dots is proposed. With the help of Landauer formula, the general expressions for the charge and heat currents, the power output and efficiency are derived. In the linear response regime an explicit analytic expressions for the charge and heat currents, the maximum power output and the corresponding efficiency is presented. Next, the performance characteristic and optimal performance of the heat engine is investigated in the nonlinear response regime by numerical calculation. Finally, the influence of the main parameters, including the asymmetry factor, the energy-level spacing, the energy difference, the number of discrete energy levels, the bias voltage, and the temperature difference on the optimal performance of the heat engine is analyzed in detail. By choosing appropriate parameters one can obtain the maximum power output and the corresponding efficiency at maximum output power

Calibrating Pan-Tilt Cameras with Telephoto Lenses

Abstract. Pan-tilt cameras are widely used in surveillance networks. These cameras are often equipped with telephoto lenses to capture objects at a distance. Such a camera makes full-metric calibration more difficult since the projection with a telephoto lens is close to orthographic. This paper discusses the problems caused by pan-tilt cameras with long focal length and presents a method to improve the calibration accuracy. Experiments show that our method reduces the re-projection errors by an order of magnitude compared to popular homographybased approaches.