7,708 research outputs found
Less is More: Micro-expression Recognition from Video using Apex Frame
Despite recent interest and advances in facial micro-expression research,
there is still plenty room for improvement in terms of micro-expression
recognition. Conventional feature extraction approaches for micro-expression
video consider either the whole video sequence or a part of it, for
representation. However, with the high-speed video capture of micro-expressions
(100-200 fps), are all frames necessary to provide a sufficiently meaningful
representation? Is the luxury of data a bane to accurate recognition? A novel
proposition is presented in this paper, whereby we utilize only two images per
video: the apex frame and the onset frame. The apex frame of a video contains
the highest intensity of expression changes among all frames, while the onset
is the perfect choice of a reference frame with neutral expression. A new
feature extractor, Bi-Weighted Oriented Optical Flow (Bi-WOOF) is proposed to
encode essential expressiveness of the apex frame. We evaluated the proposed
method on five micro-expression databases: CAS(ME), CASME II, SMIC-HS,
SMIC-NIR and SMIC-VIS. Our experiments lend credence to our hypothesis, with
our proposed technique achieving a state-of-the-art F1-score recognition
performance of 61% and 62% in the high frame rate CASME II and SMIC-HS
databases respectively.Comment: 14 pages double-column, author affiliations updated, acknowledgment
of grant support adde
A middleware for a large array of cameras
Large arrays of cameras are increasingly being employed for producing high quality image sequences needed for motion analysis research. This leads to the logistical problem with coordination and control of a large number of cameras. In this paper, we used a lightweight multi-agent system for coordinating such camera arrays. The agent framework provides more than a remote sensor access API. It allows reconfigurable and transparent access to cameras, as well as software agents capable of intelligent processing. Furthermore, it eases maintenance by encouraging code reuse. Additionally, our agent system includes an automatic discovery mechanism at startup, and multiple language bindings. Performance tests showed the lightweight nature of the framework while validating its correctness and scalability. Two different camera agents were implemented to provide access to a large array of distributed cameras. Correct operation of these camera agents was confirmed via several image processing agents
Computational Aspects of Optional P\'{o}lya Tree
Optional P\'{o}lya Tree (OPT) is a flexible non-parametric Bayesian model for
density estimation. Despite its merits, the computation for OPT inference is
challenging. In this paper we present time complexity analysis for OPT
inference and propose two algorithmic improvements. The first improvement,
named Limited-Lookahead Optional P\'{o}lya Tree (LL-OPT), aims at greatly
accelerate the computation for OPT inference. The second improvement modifies
the output of OPT or LL-OPT and produces a continuous piecewise linear density
estimate. We demonstrate the performance of these two improvements using
simulations
Opioid-sparing effects of perioperative paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs) in children.
Perioperative pain in children can be effectively managed with systemic opioids, but addition of paracetamol or nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce opioid requirements and potentially improve analgesia and/or reduce adverse effects
Vision-based tracking of a dynamic target with application to multi-axis position control
Two sub-pixel resolution approaches to measure in-plane displacements and in-plane rotation of a known target, through image processing, are described in this research. A dynamic known target is displayed on a pixel grid, which is attached to one end of the kinematic chain of an XYθZ stage; the latter represents the experimental testbed. At the other end of the kinematic chain, a digital monochrome camera is fixed to the bottom of the stage and provides 3D position information used as the feedback signal to the vision-based control system in charge of the tool’s motion. The illuminated pixels on the display are captured in real time by the digital camera, and the stage motion control system attempts to keep the displayed image in the proper location with respect to the camera image plane. The result is a direct sensing multi-DOF position feedback system. The proposed camera-pixel grid sensing setup eliminates the reliance on the kinematic model and also avoids the need for traditional error compensation techniques, along with their associated cost and complexity. Positioning resolutions on the order of 1/100th of the pixel size on the display are achieved
Anachronistic Grain Growth and Global Structure of the Protoplanetary Disk Associated with the Mature Classical T Tauri Star, PDS 66
We present ATCA interferometric observations of the old (13 Myr), nearby
(86pc) classical T Tauri star, PDS 66. Unresolved 3 and 12 mm continuum
emission is detected towards PDS 66, and upper limits are derived for the 3 and
6 cm flux densities. The mm-wave data show a spectral slope flatter than that
expected for ISM-sized dust particles, which is evidence of grain growth. We
also present HST/NICMOS 1.1 micron PSF-subtracted coronagraphic imaging of PDS
66. The HST observations reveal a bilaterally symmetric circumstellar region of
dust scattering about 0.32% of the central starlight, declining radially in
surface brightness. The light-scattering disk of material is inclined 32
degrees from face-on, and extends to a radius of 170 AU. These data are
combined with published optical and longer wavelength observations to make
qualitative comparisons between the median Taurus and PDS 66 spectral energy
distributions (SEDs). By comparing the near-infrared emission to a simple
model, we determine that the location of the inner disk radius is consistent
with the dust sublimation radius (1400 K at 0.1 AU). We place constraints on
the total disk mass using a flat-disk model and find that it is probably too
low to form gas giant planets according to current models. Despite the fact
that PDS 66 is much older than a typical classical T Tauri star (< 5 Myr), its
physical properties are not much different.Comment: 31 pages, 7 figure
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