An optical tracking sensor that produces images containing the state of polarization of each pixel can be implemented using individual wire-grid micropolarizers on each detector element of a solid-state focal plane array. These sensors can significantly improve identification and tracking of various man-made targets in cluttered, dynamic scenes such as urban and suburban environments. We present electromagnetic simulation results for wire-grid polarizers that can be fabricated on standard imaging arrays at three different technology nodes (an 80-, 250-, and 500-nm pitch) for use in polarization-sensitive detector arrays. The degradation in polarizer performance with the larger pitch grids is quantified. We also present results suggesting the performance degradation is not significant enough to affect performance in a man-made vehicle-tracking application.
The development and testing of thermal signature tracking algorithms burdens the developer with a method
of testing the algorithm's fidelity. Although actual video is normally used for testing tracking algorithms, to
evaluate performance in a variety of configurations, the acquisition of suitable video data volume is
prohibitive. As an alternative to actual video we are developing accurate synthetic thermal infrared models
of vehicles that will be incorporated into background infrared images generated using the Digital Image and
Remote Sensing Image Generation (DIRSIG) software package. Motion for the targets within the
background scene is generated using the open-source Simulation of Urban MObility (SUMOTM) software
package. ThermoAnalytics' Multi-Service Electro-optic Signature (MuSESTM) software package is used to
model thermal emission from the object of interest. The goal is to accurately incorporate thermal signatures
of moving targets into realistic radiometrically calibrated scenes, and to then test and evaluate tracking
algorithms using both visible and thermal infrared signatures for improved day and night detection
capability. The software packages have been integrated together for a synthetic video
Simulation of moving vehicle tracking has been demonstrated using hyperspectral and polarimetric imagery (HSI/PI).
Synthetic HSI/PI image cubes of an urban scene containing moving vehicle content were generated using the Rochester
Institute of Technology's Digital Imaging and Remote Sensing Image Generation (DIRSIG) Megascene #1 model.
Video streams of sensor-reaching radiance frames collected from a virtual orbiting aerial platform's imaging sensor were
used to test adaptive sensor designs in a target tracking application. A hybrid division-of-focal-plane imaging sensor
boasting an array of 2×2 superpixels containing both micromirrors and micropolarizers was designed for co-registered
HSI/PI aerial remote sensing. Pixel-sized aluminum wire-grid linear polarizers were designed and simulated to measure
transmittance, extinction ratio, and diattenuation responses in the presence of an electric field. Wire-grid spacings of 500
[nm] and 80 [nm] were designed for lithographic deposition and etching processes. Both micromirror-relayed
panchromatic imagery and micropolarizer-collected PI were orthorectified and then processed by Numerica
Corporation's feature-aided target tracker to perform multimodal adaptive performance-driven sensing of moving
vehicle targets. Hyperspectral responses of selected target pixels were measured using micromirror-commanded slits to
bolster track performance. Unified end-to-end track performance case studies were completed using both panchromatic
and degree of linear polarization sensor modes.
A novel multi-object spectrometer (MOS) is being explored for use as an adaptive performance-driven sensor that tracks
moving targets. Developed originally for astronomical applications, the instrument utilizes an array of micromirrors to
reflect light to a panchromatic imaging array. When an object of interest is detected the individual micromirrors imaging
the object are tilted to reflect the light to a spectrometer to collect a full spectrum. This paper will present example
sensor performance from empirical data collected in laboratory experiments, as well as our approach in designing optical
and radiometric models of the MOS channels and the micromirror array. Simulation of moving vehicles in a highfidelity,
hyperspectral scene is used to generate a dynamic video input for the adaptive sensor. Performance-driven
algorithms for feature-aided target tracking and modality selection exploit multiple electromagnetic observables to track
moving vehicle targets.