Browsing by Subject "Visibility"
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Item An Automatic Visibility Measurement System Based on Video Cameras(Minnesota Department of Transportation, 1998-09) Kwon, Taek MuThe Minnesota Department of Transportation (Mn/DOT) conducted a two-year study on visibility measurement methods using video cameras. This report describes the study's theoretical basis, practical methods, and experimental results. Among several methods and algorithms developed, the edge decay model along with a proper threshold technique worked best for evaluating daytime visibility. This approach estimates the distance where an object of specified size and shape is no longer distinguishable from the background in terms of edge information. For night time, a constant light source is required to evaluate visibility. Researchers developed a light diffusion model that follows an exponential decay curve. Researchers determined that the volume of light diffused out of the original source logarithmically correlates to visibility. Mn/DOT implemented day and night algorithms in the field and evaluated them using manual measurements. For daytime, visibilities measured using the edge decay model closely approximated the manual measurements on all types of weather. Unreliability of manual measurements at night made night-time evaluation very difficult. However, research verified that the trend of visibility change obtained by the proposed approach closely approximates the trend of manual measurements. 17. DocumentItem Data for Validating a Model of Architectural Hazard Visibility with Low-Vision Observers(2020-07-22) Liu, Siyun; Thompson, William B.; Liu, Yichen; Shakespeare, Robert A.; Kersten, Daniel J.; Legge, Gordon E.; liux4433@umn.edu; Liu, Siyun; Department of Psychology, University of Minnesota; School of Computing, University of Utah; Department of Theatre, Drama, and Contemporary Dance, Indiana University BloomingtonPedestrians with low vision are at risk of injury when hazards, such as steps and posts, have low visibility. This study aims at validating the software implementation of a computational model that estimates hazard visibility. The model takes as input a photorealistic 3-D rendering of an architectural space, and the acuity and contrast sensitivity of a low-vision observer, and outputs estimates of the visibility of hazards in the space. Our experiments explored whether the model can predict the likelihood of observers correctly identifying hazards. We tested fourteen normally sighted subjects with blur goggles that reduced acuity to 1.2 logMAR or 1.6 logMAR and ten low-vision subjects with acuities ranging from 0.8 logMAR to 1.6 logMAR. Subjects viewed computer-generated images of a walkway containing five possible targets ahead—large step up, large step-down, small step up, small step down, or a flat continuation. Each subject saw these stimuli with variations of lighting and viewpoint in 250 trials and indicated which of the five targets was present. The model generated a score on each trial that estimated the visibility of the target. If the model is valid, the scores should be predictive of how accurately the subjects identified the targets. We used logistic regression to examine the correlation between the scores and the participants’ responses. For twelve of the fourteen normally sighted subjects with artificial acuity reduction and all ten low-vision subjects, there was a significant relationship between the scores and the participant’s probability of correct identification. These experiments provide evidence for the validity of a computational model that predicts the visibility of architectural hazards. The software implementation of the model may be useful for architects to assess the visibility of hazards in their designs, thereby enhancing the accessibility of spaces for people with low vision.Item Deep visibility: meaningful absence and presence in the superintendency(2014-05) Kazmierczak, Wayne A.Using a qualitative research approach and a multiple case study method, this study identifies perceptions about the visibility of superintendents from various perspectives. Superintendents, school board members, community members, and staff members were interviewed and offered their varied perspectives. The literature review provided an extensive examination of the history of the superintendent, a historical view of the discursive roles of the superintendent, and a review of relevant leadership literature. The study's conceptual framework was developed using research related to reflective practice, general leadership theory, organizational learning, Theory U, social impact theory, the superintendency, and communication. A deeper visibility resulting in meaningful absence and presence in the superintendency is the essence of this framework. Key findings included aspects of presence, which included the terms adverse, accessible, authentic, beyond physical, transparent, trustworthy and synergetic. Aspects of absence identified in the study included symbolic, job pressures, tied to desk, privacy and contra-visibility. Areas noted for future research include adverse visibility, contra-visibility, synergetic visibility, reflection and symbolic absence. The concept, superintendent visibility, has previously lacked meaningful structure and, therefore, has been described, in the past, through general discussions rather than through an empirical lens. A Model of Superintendent Visibility was developed after careful analysis of the data, consideration of the study's conceptual framework and literature review, and the study's identified conclusions.Item Missing bridges: the invisible (and hypervisible) lesbian of color in theory, publishing, and media(2013-05) DeLong, Renee AnnWhile moving from theory, through the Women in Print Movement, and up to the current images of lesbians this dissertation considers how the figure of the lesbian of color has been erased and highlighted at different times and in different spaces. Chapter one, "What Does Invisibility Look Like?" examines how and where the figure of the lesbian of color is overlooked, squeezed out, or tokenized. In chapter 2: "Rhetorically irreverent, politically radical, and deeply personal: Lesbians of Color Organize," the work of the Azalea Collective in Brooklyn, NY, the Combahee River Collective in Boston, MA, Cherríe Moraga and Gloria Anzaldua's planning for This Bridge Called My Back: Writings by Radical Women of Color, and the work of Kitchen Table Press are explored. Chapter three, "Publishing and Perishing: The Women in Print Movement from 1980-2002," compares the climate in 1981 when This Bridge Called my Back: Radical Women of Color Speak Out was published to the climate for Sing, Whisper, Shout, Pray: Feminist Visions for a Just World in 2002. Chapter four, "What's visible now? The Creation of [White] Lesbian Celebrities" examines the classed and racialized messages embedded in the media figures of Rachel Maddow, Suze Orman, and Ellen DeGeneres.Item Performance Analysis of Squad Car Lighting, Retro-reflective Markings, and Paint Treatments to Improve Safety at Roadside Traffic Stops(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-05) Fischer, Jacob; Krzmarzick, Adam; Menon, Arvind; Shankwitz, CraigIn the United States, more police officers are killed in collisions at roadside stops than through felonious acts. Causal factors that affect police safety at roadside stops include officer conspicuity, squad conspicuity, weather conditions, and the attention and fatigue level of the traveling public. Described herein is a research project that provides insight and guidelines that may ultimately improve officer safety at roadside stops. The project is designed to modify an existing sensor-based traffic monitoring system so that it serves as a test bed to evaluate the retro-reflector, lighting, and paint treatments of an emergency vehicle to determine whether particular combinations produce improved “move over” behavior of oncoming traffic. This is done using automated data analysis software built specifically for this project. Tests are performed at a fully instrumented rural intersection. After mimicking a traffic stop where a patrol vehicle is placed at this intersection, the experimenter logs onto a website and enters the time when the test took place. Analysis software draws results from the data. The results are e-mailed to the experimenters, who devise their own test regimes, following the guidelines presented herein, and draw their own conclusions. A second system was built to provide a more portable option for testing in urban areas. This system consists of two freestanding radar boxes with wireless communication, as well as one netbook computer. Test procedures and results are analogous to the original system. Additional calibration is automatically performed to account for the variable position of the radars.Item Role of Visual Affordance of a Spatial Layout on Human Interactions at a Work Environment(2016-08) Motamed, MandanaThis study explores the impact of the spatial layout of a work environment on employees’ interactions. The main research question is: How does the visual affordance of the spatial layout of a work environment influence the way employees interact? It was addressed quantitatively by means of quasi-experimental design and a cross-sectional survey design. A social interaction was selected as the unit of analysis. Spatial data was gathered through the use of a simple floor plan analysis as well as DepthmapX utilizing the theory of space syntax. Social data was collected by means of a controlled field observation (video-taping) and administration of a survey questionnaire. This study discovered that 1) visual control is an important issue to be considered in the design of work environments; 2) the theory of space syntax can be regarded as a reliable predictor of the interrelationship between spatial as well as social properties of the space; 3) results are not generalizable to other settings; 4) To achieve a robust statistical power, the unit of analysis can be set on an interaction or a spatial unit ; 5) more studies is required to identify generalizable trends on the interrelationship between spatial properties of work settings and their social attributes.