In pursuit of real time/on-the-fly image processing, a sensor with embedded algorithms for tracking is tested to determine its aliasing window whilst under laser interrogation. The characterization of the sensors and this interaction are explored, as well as the limitations thereof. This is follow on work to previous studies, in which both fixed frame rate sensors and adjustable frame rate sensors were tested to show the difference in response and functionality when subjected to Quantum Cascade Laser (QCL) modulation. A MIRAGE[1] Infrared Scene Projector (IRSP) is used to add baseline signature for the sensor to follow before the laser signal is introduced. Discussions of further advancements in anti-aliasing algorithms are included as well.
In this paper, we discuss the testing image processing algorithms for mitigation of aliasing artifacts under pulsed illumination. Previously sensors were tested, one with a fixed frame rate and one with an adjustable frame rate, which results showed different degrees of operability when subjected to a Quantum Cascade Laser (QCL) laser pulsed at the frame rate of the fixe-rate sensor. We implemented algorithms to allow the adjustable frame-rate sensor to detect the presence of aliasing artifacts, and in response, to alter the frame rate of the sensor. The result was that the sensor output showed a varying laser intensity (beat note) as opposed to a fixed signal level.
A MIRAGE Infrared Scene Projector (IRSP) was used to explore the efficiency of the new algorithms, introduction secondary elements into the sensor's field of view.
Radiometrically accurate simulation of InfraRed (IR) signatures is an essential prerequisite for valid IR sensor testing
within the IR Scene Projection (IRSP) community. The Electronic Combat Stimulation (ECSTIM) Branch EO/IR
Laboratory at the NAVAIR Air Combat Environment T&E Facility (ACETEF), NAWC-AD, Patuxent River, Maryland
has recently begun validation testing of their Large Format Resistive-emitter Array (LFRA) IRSP. This is in preparation
for developmental and operational testing of emerging mission-critical IR Countermeasure (IRCM) systems. Validation
is guided by the Navy Air Defense Threat Simulator Validation Procedures Manual (NAWCWPNS TM 7489-3) and will
support s other emerging high priority development programs such as the Joint Distributed IRCM Ground-test System
(JDIGS). This paper discusses the ECSTIM/EO/IR Laboratory LFRA IRSP validation testing process, the resulting data
collection, measurements and analysis.
The QUick Image Display (QUID) model accurately computes and displays radiance images of aircraft and other
objects, generically called targets, at animation rates while the target undergoes unrestricted flight. Animation rates are
obtained without sacrificing radiometric accuracy by using two important innovations. First, QUID has been
implemented using the Open Scene Graph (OSG) library, an open-source, cross-platform 3-D graphics toolkit for the
development of high performance graphics applications in the fields of visual simulation, virtual reality, scientific
visualization and modeling. Written entirely in standard C++ and fully encapsulating OpenGL and its extensions, OSG
exploits modern graphics hardware to perform the computationally intensive calculations such as hidden surface
removal, 3-D transformations, and shadow casting. Second, a novel formulation for reflective/emissive terms enables
rapid and accurate calculation of per-vertex radiance. The bi-directional reflectance distribution function (BRDF) is a
decomposed into separable spectral and angular functions. The spectral terms can be pre-calculated for a user specified
band pass and for a set of target-observer ranges. The only BRDF calculations which must be performed during target
motion involves the observer-target-source angular functions. QUID supports a variety of target geometry files and is
capable of rendering scenes containing high level-of-detail targets with thousands of facets. QUID generates accurate
visible to LWIR radiance maps, in-band and spectral signatures. The newest features of QUID are illustrated with
radiance and apparent temperature images of threat missiles as viewed by an aircraft missile warning system.
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