Pose Estimation for Augmented Reality: A Hands-On Survey Marchand, Eric; Uchiyama, Hideaki; Spindler, Fabien
IEEE transactions on visualization and computer graphics,
2016-Dec.-1, 2016-12-00, 2016-12-1, 20161201, 2016-12, Letnik:
22, Številka:
12
Journal Article
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Odprti dostop
Augmented reality (AR) allows to seamlessly insert virtual objects in an image sequence. In order to accomplish this goal, it is important that synthetic elements are rendered and aligned in the ...scene in an accurate and visually acceptable way. The solution of this problem can be related to a pose estimation or, equivalently, a camera localization process. This paper aims at presenting a brief but almost self-contented introduction to the most important approaches dedicated to vision-based camera localization along with a survey of several extension proposed in the recent years. For most of the presented approaches, we also provide links to code of short examples. This should allow readers to easily bridge the gap between theoretical aspects and practical implementations.
A novel osmotic membrane bioreactor (OsMBR) is presented. The system utilizes a submerged forward osmosis (FO) membrane module inside a bioreactor. Through osmosis, water is transported from the ...mixed liquor across a semi-permeable membrane, and into a draw solution (DS) with a higher osmotic pressure. To produce potable water, the diluted DS is treated in a reverse osmosis (RO) unit; the by-product is a reconcentrated DS for reuse in the FO process. Preliminary results from experiments conducted with a flat-sheet cellulose triacetate FO membrane demonstrated high sustainable flux and relatively low reverse transport of solutes from the DS into the mixed liquor. Membrane fouling was controlled with osmotic backwashing. The FO membrane was found to reject 98% of organic carbon and 90% of ammonium-nitrogen; the OsMBR process (bioreactor and FO membrane) was found to remove greater than 99% of organic carbon and 98% of ammonium-nitrogen, respectively; suggesting a better compatibility of the OsMBR with downstream RO systems than conventional membrane bioreactors.
With the recent focus on using advanced water treatment processes for water reuse, interest is growing for utilizing enhanced coagulation to remove dissolved chemical species. Up to 85% of the ...nitrogen in wastewater effluent is made up of dissolved organic nitrogen (DON), but there is a knowledge gap regarding its removal during coagulation, which can be influenced by DON characteristics. To address this issue, tertiary-treated wastewater samples were analyzed before and after coagulation with polyaluminum chloride and ferric chloride. Samples were size-fractionated into four molecular weight fractions (0.45 μm, 0.1 μm, 10 kDa, and 3 kDa) using vacuum filtration and ultrafiltration. Each fraction was further evaluated by coagulating it separately to assess DON removal during enhanced coagulation. The size fractionated samples were also separated into hydrophilic and hydrophobic fractions using C18 solid phase extraction disks. Fluorescence excitation-emission matrices were used to investigate the characteristics of dissolved organic matter contributing to DON during the coagulation process. The results showed that DON compounds of size <3 kDa constituted a majority of the total DON. Coagulation removed more than 80% DON from size fractions 0.45 μm–0.1 μm and 0.1 μm-10 kDa, but less than 20% was removed from 10 kDa to 3 kDa and <3 kDa fractions. Coagulation on pre-filtered samples removed 19% and 25% of the <3 kDa DON fraction using polyaluminum chloride and ferric chloride, respectively. In all molecular weight fractions, hydrophilic DON compounds were found to be dominant (>90%), and enhanced coagulation was not effective in removing hydrophilic DON compounds. LMW fractions respond poorly to enhanced coagulation due to their hydrophilic nature. Enhanced coagulation effectively removes humic acid-like substances, but poorly removes proteinaceous compounds such as tyrosine and tryptophan. This study's findings provide insights into DON behavior during coagulation and factors affecting its removal, potentially improving wastewater treatment strategies.
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•Enhanced coagulation for DON removal from wastewater with metal-based coagulants.•Higher molecular weight DON compounds are better removed by enhanced coagulation.•Low molecular weight DON compounds are recalcitrant because of its hydrophilicity.•Humic-like substances are better removed during enhanced coagulation process.•Tryptophan- and tyrosine-like proteins are recalcitrant to enhanced coagulation.
In this paper, we present a direct image registration approach that uses mutual information (MI) as a metric for alignment. The proposed approach is robust and gives an accurate estimation of a set ...of 2-D motion parameters in real time. MI is a measure of the quantity of information shared by signals. Although it has the ability to perform robust alignment with illumination changes, multimodality, and partial occlusions, few works have proposed MI-based applications related to spatiotemporal image registration or object tracking in image sequences because of some optimization problems, which we will explain. In this paper, we propose a new optimization method that is adapted to the MI cost function and gives a practical solution for real-time tracking. We show that by refining the computation of the Hessian matrix and using a specific optimization approach, the registration results are far more robust and accurate than the existing solutions, with the computation also being cheaper. A new approach is also proposed to speed up the computation of the derivatives and keep the same optimization efficiency. To validate the advantages of the proposed approach, several experiments are performed.
Most wastewater treatment facilities that satisfy stricter discharge restrictions for nutrients, remove dissolved inorganic nitrogen (DIN) species efficiently, leaving dissolved organic nitrogen ...(DON) to be present at a higher proportion (up to 85 %) of total nitrogen (TN) in the effluent. Discharged DON promotes algae growth in receiving water bodies and is a growing concern in effluent potable reuse applications considering its potential to form hazardous nitrogenous disinfection byproducts (N-DBPs). Enhanced coagulation is an established process in the advanced water treatment train for most potable reuse applications. However, so far, no information has been collected at the pilot scale to address DON removal efficiency and process implications by enhanced coagulation under real conditions. This study performed a comprehensive evaluation of DON removal from the effluent of the Truckee Meadows Water Reclamation Facility (TMWRF) by enhanced coagulation over the course of 11 months at the pilot scale. Three different coagulants (aluminum sulfate (alum), poly‑aluminum chloride (PACl), ferric chloride (FC)) and a cationic polymer coagulant aid (Clarifloc) were used. Optimum doses for each coagulant and polymer and ideal pH were determined by jar tests and applied at the pilot. Alum (24 mg/L) resulted in highly variable DON removal (6 % – 40 %, 21 % on average), which was enhanced by the addition of polymer, leading to 32 % DON removal on average. PACl (40 mg/L) and FC (100 mg/L) resulted in more consistent DON removal (on average 45 % and 57 %, respectively); however, polymer addition exerted minimal enhancement for these coagulants. Overall, enhanced coagulation effectively reduced DON in the tertiary effluent at the pilot scale. The treatment showed auxiliary benefits, including dissolved organic carbon (DOC) and orthophosphate removal.
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•Dissolved organic nitrogen removal from wastewater using enhanced coagulation•20–60 % dissolved organic nitrogen removal achieved at the pilot scale•Ferric chloride outperformed aluminum-based coagulants•Enhanced coagulation did not effectively remove inorganic nitrogen (NH4-N, NOxN)•Dissolved organic carbon and orthophosphate were removed by enhanced coagulation
A novel osmotic membrane bioreactor-membrane distillation (OMBR-MD) system was designed and fabricated to treat wastewater for potable reuse. Before longer-term operation to evaluate water flux and ...biological treatment of the pilot-scale OMBR subsystem, two forward osmosis (FO) membranes were evaluated at the bench-scale. There was no statistical difference between cellulose triacetate and thin-film composite membrane performance for activated sludge feed solution. Also, FO water flux during long-term operation was the same for 20 and 35g/L NaCl draw solutions; however, the 35g/L NaCl draw solution resulted in greater reverse salt flux and higher conductivity in the bioreactor. The OMBR subsystem was integrated with an MD subsystem to reconcentrate the draw solution and produce high quality product water. Results from long-term testing using a high-strength wastewater showed 98.4% COD removal and 90.2% NH4+-N could be achieved with a single bioreactor by alternating aeration on/off cycles to control the redox environment. An automated dosing and transfer system was developed to maintain constant FO draw solution concentration and prevent heat from being transferred to the bioreactor, which is critical for maintaining biological nitrogen removal.
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•OMBR was coupled to MD to treat high-strength wastewater for potable reuse.•Carbon and nitrogen removal was achieved in a single-tank OMBR system.•The integrated OMBR-MD system achieved 90.2% NH4+-N removal and 98.4% COD removal.•Automated dosing and transfer systems enabled water production without transfer of heat to the bioreactor.•CTA and TFC membrane performance was the same with activated sludge feed solution at bench-scale.
Wastewater treatment for indirect potable reuse (IPR) is a possible approach to address water scarcity. In this study, a novel membrane bioreactor–membrane distillation (MBR-MD) system was evaluated ...to determine the environmental impacts of treatment compared to an existing IPR facility (“Baseline”). Physical and empirical models were used to obtain operational data for both systems and inform a life cycle inventory. Life cycle assessment (LCA) was used to compare the environmental impacts of each system. Results showed an average 53.7% reduction in environmental impacts for the MBR-MD system when waste heat is used to operate MD; however, without waste heat, the environmental impacts of MBR-MD are significantly higher, with average impacts ranging from 218% to 1400% greater than the Baseline, depending on the proportion of waste heat used. The results of this study demonstrate the effectiveness of the novel MBR-MD system for IPR and the reduced environmental impacts when waste heat is available to power MD.
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