75 research outputs found
Human action recognition using mutual invariants
No full textStatic and temporally varying 3D invariants are proposed for capturing the spatio-temporal dynamics of a general human action to enable its representation in a compact, view-invariant manner. Two variants of the representation are presented and studied: (1) a restricted-3D version, whose theory and implementation are simple and efficient but which can be applied only to a restricted class of human action, and (2) a full-3D version, whose theory and implementation are more complex but which can be applied to any general human action. A detailed analysis of the two representations is presented. We show why a straightforward implementation of the key ideas does not work well in the general case, and present strategies designed to overcome inherent weaknesses in the approach. What results is an approach for human action modeling and recognition that is not only invariant to viewpoint, but is also robust enough to handle different people, different speeds of action (and hence, frame rate) and minor variabilities in a given action, while encoding sufficient distinction among actions. Results on 2D projections of human motion capture and on manually segmented real imag
View independent human body pose estimation from a single perspective image
No full textRecovering the 3D coordinates of various joints of the human body from an image is a critical first step for several model-based human tracking and optical motion capture systems. Unlike previous approaches that have used a restrictive camera model or assumed a calibrated camera, our work deals with the general case of a perspective uncalibrated camera and is thus well suited for archived video. The input to the system is an image of the human body and correspondences of several body landmarks, while the output is the set of 3D coordinates of the landmarks in a bodycentric coordinate system. Using ideas from 3D model based invariants, we set up a polynomial system of equations in the unknown head pitch, yaw and roll angles. If we are able to make the often-valid assumption that torso twist is small, we show that there exists a finite number of solutions to the head-orientation which can be computed readily. Once the head orientation is computed, the epipolar geometry of the camera is recovered, leading to solutions to the 3D joint positions. Results are presented on synthetic and real images. 1
Quasi-invariants for human action representation and recognition
No full textAlthough human action recognition has been the subject of much research in the past, the issue of viewpoint invariance has received scarce attention. In this paper, we present an approach to detect human action with a high tolerance to viewpoint change. Canonical body poses are modeled in a view invariant manner to enable detection from a general viewpoint. While there exist no invariants for 3D to 2D projection, there exists a wealth of techniques in 2D invariance that can be used to advantage in 3D to 2D projection. We employ 2D invariants to recognize canonical poses of the human body leading to an effective way to represent and recognize human action which we evaluate theoretically and experimentally on 2D projections of publicly available human motion capture data. 1
OrpheusDB: an attempt towards data version control on relational database
No full textThis thesis will cover the deign, manual, and implementation detail of OrpheusDB.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-12-01The student, Sili Hui, accepted the attached license on 2016-12-06 at 22:28.The student, Sili Hui, submitted this Thesis for approval on 2016-12-06 at 22:34.This Thesis was approved for publication on 2016-12-07 at 09:14.DSpace SAF Submission Ingestion Package generated from Vireo submission #10439 on 2017-02-28 at 14:37:18Made available in DSpace on 2017-03-01T16:37:06Z (GMT). No. of bitstreams: 2
HUI-THESIS-2016.pdf: 370407 bytes, checksum: 5d25b70350d18de43d3eb78eb2ceacaa (MD5)
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Previous issue date: 2016-12-07Embargo set by: Seth Robbins for item 98627
Lift date: 2019-03-01T16:37:19Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 98627 on 2019-03-02T10:15:17Z
Role of bicarbonate as a pH buffer and electron sink in microbial dechlorination of chloroethenes
No full textAbstract Background Buffering to achieve pH control is crucial for successful trichloroethene (TCE) anaerobic bioremediation. Bicarbonate (HCO3−) is the natural buffer in groundwater and the buffer of choice in the laboratory and at contaminated sites undergoing biological treatment with organohalide respiring microorganisms. However, HCO3− also serves as the electron acceptor for hydrogenotrophic methanogens and hydrogenotrophic homoacetogens, two microbial groups competing with organohalide respirers for hydrogen (H2). We studied the effect of HCO3− as a buffering agent and the effect of HCO3−-consuming reactions in a range of concentrations (2.5-30 mM) with an initial pH of 7.5 in H2-fed TCE reductively dechlorinating communities containing Dehalococcoides, hydrogenotrophic methanogens, and hydrogenotrophic homoacetogens. Results Rate differences in TCE dechlorination were observed as a result of added varying HCO3− concentrations due to H2-fed electrons channeled towards methanogenesis and homoacetogenesis and pH increases (up to 8.7) from biological HCO3− consumption. Significantly faster dechlorination rates were noted at all HCO3− concentrations tested when the pH buffering was improved by providing 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) as an additional buffer. Electron balances and quantitative PCR revealed that methanogenesis was the main electron sink when the initial HCO3− concentrations were 2.5 and 5 mM, while homoacetogenesis was the dominant process and sink when 10 and 30 mM HCO3− were provided initially. Conclusions Our study reveals that HCO3− is an important variable for bioremediation of chloroethenes as it has a prominent role as an electron acceptor for methanogenesis and homoacetogenesis. It also illustrates the changes in rates and extent of reductive dechlorination resulting from the combined effect of electron donor competition stimulated by HCO3− and the changes in pH exerted by methanogens and homoacetogens.</p
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