Multispectral (MS) and hyperspectral (HS) sensors can facilitate target or anomaly detection in clutter since natural clutter and man-made objects diff er in the energy they radiate across the electromagnetic spectrum. Previous research in anomaly detection has formulated two popular algorithms: those based on Gauss-Markov Random Fields (GMRF) and the so-called RX-detector. Performance of these algorithms is dependent on a number of issues including spatial resolution, spectral correlation between the imaging bands, clutter/target model accuracy and the acquired data's signal-to-noise ratio (SNR). This paper provides a comparison study of the anomaly detection performance of the RXdetector and the GMRF-based algorithm using: (1) 4m MS imagery acquired f rom the IKONOS satellite and (2) pansharpened 1m MS imagery created by fusing the 4m MS and the associated 1m panchromatic image sets. The study will be based on the detection performance for stationary and slow moving targets selected f rom imagery acquired during training exercises at Canadian Forces Base (CFB) Petawawa and CFB Wainwright, Canada.
Stimulated Brillouin scattering (SBS), in an optical fiber, is a
three-wave interaction (3WI) resulting from a coupling between
light and acoustic waves. In a fiber optic sensing context, SBS
results from the interaction between counterpropagating pulsed and
continuous fields. We formulate a solution to the time dependant,
one dimensional 3WI model in a SBS based fiber optic sensor. It is
shown that a low complexity, first order finite difference time
domain (FDTD) solution is capable of accurately modelling the
dynamics of SBS with little computational effort. A modification
to the first order scheme is proposed to combat numerical damping
and dispersion, brought on by the low order of the solution.
Examples are presented, validating the performance of our
modelling technique. The effect of pulse power and risetime on the
resulting scattering is examined, along with the effects of
γa, an intrinsic fibre parameter related to the linewidth of the Brillouin spectrum. The spatial and temporal evolution of the acoustic field is illustrated; the effect of the steady state value of this field on the 3WI is investigated. The steady state acoustic field strength is related to the extinction ratio of the pulsed source, and it is found that this parameter has a
significant influence on the scattering. This type of modelling provides a rapid means of investigating SBS as a tool in fiber optic sensing.