144,943 research outputs found
Statistical Modeling of Optical Flow
Optical flow estimation is one of the main subjects in computer vision. Many methods developed to compute the motion fields are built using standard heuristic formulation. In this paper, however, we learn a motion model. We de-velop a hybrid model by combining the learnt model with Markov Random Field (MRF). And then we introduce a method based on ”Radial Basis Function Neural Network” (RBF) to learn the model. When computing the displace-ment field, a Gaussian pyramidal down-sampling decom-position technique is employed. At each pyramidal level, we use bi-linear interpolation combined with an efficient warping technique to generate a residual image, which is then used at the finer level to compute the flow. To mini-mize the energy, we use two different discrete optimization methods: Graph-Cut algorithm, Tree-Reweighted Message Passing (TRW-S) algorithm. Results are demonstrated for our approach on synthetic images and fluid images from the real world. 1
Deep Optical Flow Estimation Via Multi-Scale Correspondence Structure Learning
As an important and challenging problem in computer vision, learning based
optical flow estimation aims to discover the intrinsic correspondence structure
between two adjacent video frames through statistical learning. Therefore, a
key issue to solve in this area is how to effectively model the multi-scale
correspondence structure properties in an adaptive end-to-end learning fashion.
Motivated by this observation, we propose an end-to-end multi-scale
correspondence structure learning (MSCSL) approach for optical flow estimation.
In principle, the proposed MSCSL approach is capable of effectively capturing
the multi-scale inter-image-correlation correspondence structures within a
multi-level feature space from deep learning. Moreover, the proposed MSCSL
approach builds a spatial Conv-GRU neural network model to adaptively model the
intrinsic dependency relationships among these multi-scale correspondence
structures. Finally, the above procedures for correspondence structure learning
and multi-scale dependency modeling are implemented in a unified end-to-end
deep learning framework. Experimental results on several benchmark datasets
demonstrate the effectiveness of the proposed approach.Comment: 7 pages, 3 figures, 2 table
A Deep-structured Conditional Random Field Model for Object Silhouette Tracking
In this work, we introduce a deep-structured conditional random field
(DS-CRF) model for the purpose of state-based object silhouette tracking. The
proposed DS-CRF model consists of a series of state layers, where each state
layer spatially characterizes the object silhouette at a particular point in
time. The interactions between adjacent state layers are established by
inter-layer connectivity dynamically determined based on inter-frame optical
flow. By incorporate both spatial and temporal context in a dynamic fashion
within such a deep-structured probabilistic graphical model, the proposed
DS-CRF model allows us to develop a framework that can accurately and
efficiently track object silhouettes that can change greatly over time, as well
as under different situations such as occlusion and multiple targets within the
scene. Experiment results using video surveillance datasets containing
different scenarios such as occlusion and multiple targets showed that the
proposed DS-CRF approach provides strong object silhouette tracking performance
when compared to baseline methods such as mean-shift tracking, as well as
state-of-the-art methods such as context tracking and boosted particle
filtering.Comment: 17 page
Modeling Quantum Optical Components, Pulses and Fiber Channels Using OMNeT++
Quantum Key Distribution (QKD) is an innovative technology which exploits the
laws of quantum mechanics to generate and distribute unconditionally secure
cryptographic keys. While QKD offers the promise of unconditionally secure key
distribution, real world systems are built from non-ideal components which
necessitates the need to model and understand the impact these non-idealities
have on system performance and security. OMNeT++ has been used as a basis to
develop a simulation framework to support this endeavor. This framework,
referred to as "qkdX" extends OMNeT++'s module and message abstractions to
efficiently model optical components, optical pulses, operating protocols and
processes. This paper presents the design of this framework including how
OMNeT++'s abstractions have been utilized to model quantum optical components,
optical pulses, fiber and free space channels. Furthermore, from our toolbox of
created components, we present various notional and real QKD systems, which
have been studied and analyzed.Comment: Published in: A. F\"orster, C. Minkenberg, G. R. Herrera, M. Kirsche
(Eds.), Proc. of the 2nd OMNeT++ Community Summit, IBM Research - Zurich,
Switzerland, September 3-4, 201
Statistical Studies of Fading in Underwater Wireless Optical Channels in the Presence of Air Bubble, Temperature, and Salinity Random Variations (Long Version)
Optical signal propagation through underwater channels is affected by three
main degrading phenomena, namely absorption, scattering, and fading. In this
paper, we experimentally study the statistical distribution of intensity
fluctuations in underwater wireless optical channels with random temperature
and salinity variations as well as the presence of air bubbles. In particular,
we define different scenarios to produce random fluctuations on the water
refractive index across the propagation path, and then examine the accuracy of
various statistical distributions in terms of their goodness of fit to the
experimental data. We also obtain the channel coherence time to address the
average period of fading temporal variations. The scenarios under consideration
cover a wide range of scintillation index from weak to strong turbulence.
Moreover, the effects of beam-collimator at the transmitter side and aperture
averaging lens at the receiver side are experimentally investigated. We show
that the use of a transmitter beam-collimator and/or a receiver aperture
averaging lens suits single-lobe distributions such that the generalized Gamma
and exponential Weibull distributions can excellently match the histograms of
the acquired data. Our experimental results further reveal that the channel
coherence time is on the order of seconds and larger which implies to
the slow fading turbulent channels
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