Browsing by Subject "Placement"
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Item Calibration and component placement in structured light systems for 3D reconstruction tasks.(2009-10) Bird, Nathaniel DavisThis thesis examines the amount of detail in 3D scene reconstruction that can be extracted using structured-light camera and projector based systems. Structured light systems are similar to multi-camera stereoscopic systems, except that a projector is use in place of at least one camera. This aids 3D scene reconstruction by greatly simplifying the correspondence problem, i.e., identifying the same world point in multiple images. The motivation for this work comes from problems involved with the helical tomotherapy device in use at the University of Minnesota. This device performs conformal radiation therapy, delivering high radiation dosage to certain patient body areas, but lower dosage elsewhere. The device currently has no feedback as to the patient's body positioning, and vision-based methods are promising. The tolerances for such tracking are very tight, requiring methods that maximize the quality of reconstruction through good element placement and calibration. Optimal placement of cameras and projectors for specific detection tasks is examined, and a mathematical basis for judging the quality of camera and projector placement is derived. Two competing interests are taken into account for these quality measures: the overall visibility for the volume of interest, i.e., how much of a target object is visible; and the scale of visibility for the volume of interest, i.e., how precisely points can be detected. Optimal calibration of camera and projector systems is examined as well. Calibration is important as poor calibration will ultimately lead to a poor quality reconstruction. This is a difficult problem because projected patterns do not conform to any set geometric constraints when projected onto general scenes. Such constraints are often necessary for calibration. However, it can be shown that an optimal image-based calibration can be found for camera and projector systems if there are at least two cameras whose views overlap that of the projector. The overall quality of scene reconstruction from structured light systems is a complex problem. The work in this thesis analyzes this problem from multiple directions and provides methods and solutions that can be applied to real-world systems.Item Mathematics placement decisions for high school students with high incidence disabilities: a collective case study(2013-04) Murzyn, Amy LeeThe purpose of this multiple case study is to describe the experiences of case managers making mathematics placement decisions of high school students with high incidence disabilities. There is much information about what should be happening when making mathematics placement decisions of high school students with high incidence disabilities, but there is little research to describe what is happening. Participants include: three parents of high school students with a high incidence disability, three high school students with a high incidence disability, three case managers of a high school student with a high incidence disability, three high school mathematics teachers and three high school administrators from three different high schools in three different geographic areas: rural, suburban and urban. Four major findings emerged: 1. The placement process is a team decision. 2. Course options, the master schedule and graduation requirements are influential in the placement process. 3. A range of special education services are available, but not all needs are being met. 4. Data provides a jumping off point. Three recommendations for further research emerged: 1. Based on the limitations of the current study in regards to generalizabililty, a survey of a large sample of case managers should be conducted across the state of Minnesota and/or the country, to evaluate the degree to which the same or similar findings may be uncovered regarding the placement process and the factors surrounding placement decisions. 2. Because perceived lack of meaningful participation among parents was common among all sites, a mixed methods study could be utilized to determine how meaningful participation could be improved. 3. During this study, student needs and the perception that student needs were not being met was a common theme across cases and participants. A similar follow-up study should be undertaken to determine a definition of “needs” and how best to meet those needs.Item Timing Driven Analytical Placement for FPGA(2015-09) Agashiwala, NimishConventional Simulated Annealing (SA) based placement methods for FPGAs give best results in terms of wirelength and critical path delay. The runtime for these SA based methods is directly proportional to the total number of cells to be placed. In case of modern multi-million gate FPGAs, SA based methods for placement dominate the total runtime in the FPGA CAD flow. In this thesis, we propose a new fast and efficient timing driven analytical placement engine targeted at global placement for FPGAs followed by low temperature SA for detailed placement. Our global placement engine uses quadratic programming approach to minimize the wirelength and dynamic net weights based on timing criticality between the blocks to minimize the critical path delay. The placement engine proceeds by iteratively partitioning the placement area and making the Configurable Logic Blocks (CLBs) move near each partition's Center of Gravity (CG). After each iteration, to calculate the timing criticality between each CLB, they are snapped to physical grid locations. The placement engine uses this timing feedback to update the net weights and calculate new coordinates for the CLBs in the next iteration. We employ a spiral legalization method in the end to obtain a legalized placement which then undergoes low temperature Simulated Annealing in VPR to give comparable or better critical path delay and 8.7% bad overall wirelength after placement. Experimental results of 20 largest MCNC benchmark circuits show that our global placement engine outperforms the state-of-the-art academic placer VPR 7.0 in terms of runtime by 30% on an average, making it scalable and provides an overall similar QoR in terms of critical path delay.