Steven K. Moyer

Active and Passive Millimeter and Sub-Millimeter-Wave Imaging

We have developed several millimeter/submillimeter/terahertz systems to study active and passive imaging and associated phenomenology. For measuring the transmission and scattering properties of materials, we have developed a dual rotary stage scattering system with active illumination and a Fourier Transform spectrometer. For imaging studies, we have developed a system based on a 12-inch diameter raster-scanned mirror. By interchange of active sources and both heterodyne and bolometric detectors, this system can be used in a variety of active and passive configurations. The laboratory measurements are used as inputs for, and model calibration and validation of, a terahertz imaging system performance model used to evaluate different imaging modalities for concealed weapon identification. In this paper, we will present examples of transmission and scattering measurements for common clothing as well as active imaging results that used a 640 GHz source and receiver.

Comparing masked target transform volume (MTTV) clutter metric to human observer evaluation of visual clutter

The Night Vision and Electronic Sensors Directorates current time-limited search (TLS) model, which makes use of the targeting task performance (TTP) metric to describe image quality, does not explicitly account for the effects of visual clutter on observer performance. The TLS model is currently based on empirical fits to describe human performance for a time of day, spectrum and environment. Incorporating a clutter metric into the TLS model may reduce the number of these empirical fits needed. The masked target transform volume (MTTV) clutter metric has been previously presented and compared to other clutter metrics. Using real infrared imagery of rural images with varying levels of clutter, NVESD is currently evaluating the appropriateness of the MTTV metric. NVESD had twenty subject matter experts (SME) rank the amount of clutter in each scene in a series of pair-wise comparisons. MTTV metric values were calculated and then compared to the SME observers rankings. The MTTV metric ranked the clutter in a similar manner to the SME evaluation, suggesting that the MTTV metric may emulate SME response. This paper is a first step in quantifying clutter and measuring the agreement to subjective human evaluation.

Mid-wave infrared target source characteristics for focal plane applications

The U.S. Army is currently investigating the differences between various bands in the midwave and long wave infrared spectrum. A holistic approach to quantifying scene information is used in previous research. That is, both natural backgrounds and vehicles are present in scenes when correlation analyses are performed. Similar research has also been performed using hyperspectral imagers. Hyperspectral imagers inherently have poor signal-to-noise ratio (SNR). In this research, a mid-wave infrared broadband sensor was cold-filtered to provide four sub-bands in the mid wave region. A multi-waveband sensor as used to collect midwave infrared imagery of military vehicles and natural backgrounds. Three blackbody sources were placed at the same range as the vehicles for radiometric calibration. The goals were to collect radiometrically corrected data of various targets and process this data for comparative analysis. The images were segmented to remove all unwanted imagery from the images under observation. Correlations were performed to assess the differences in information content.

Target recognition performance as a function of sampling

The effect of sampling, or aliasing, on target recognition performance (discriminating between armored tracked, armored wheeled, and soft wheeled classes of tactical vehicles) is investigated in this research. A recognition target set was processed with various levels of blur and aliasing. Integrated spurious response levels were set to 0, 0.3, 0.6, and 0.9. A perception experiment was conducted with U.S. Army soldiers at Ft. Benning, Georgia to determine the impact of blur and aliasing on recognition performance. The results are described in this paper.

Human target acquisition performance

The battlefield has shifted from armored vehicles to armed insurgents. Target acquisition (identification, recognition, and detection) range performance involving humans as targets is vital for modern warfare. The acquisition and neutralization of armed insurgents while at the same time minimizing fratricide and civilian casualties is a mounting concern. U.S. Army RDECOM CERDEC NVESD has conducted many experiments involving human targets for infrared and reflective band sensors. The target sets include human activities, hand-held objects, uniforms & armament, and other tactically relevant targets. This paper will define a set of standard task difficulty values for identification and recognition associated with human target acquisition performance.

Performance characteristics of the masked target transform volume clutter metric

Abstract. Prior work has shown that the masked target transform volume (MTTV) clutter metric provides a measure of scene clutter that better correlates to measured probability of detection for human observers than several previously published clutter metrics. Several factors involved in using the MTTV to assess clutter in imagery are discussed here. A previously published modification to the MTTV metric to provide a normalized output value comparable across different image sets regardless of scene size is reviewed. Initial MTTV development required knowledge of a scene’s target signature and produced an unbounded metric value. Metric behavior is discussed for the case in which an average of several target signatures is used in place of a specific target signature. This allows the MTTV to be calculated for images that do not contain a target. It is shown that the user may trade computational efficiency with metric accuracy to suit a particular application. The sensitivity of the metric to variations in image noise level, target segmentation error, and viewing distance are also presented.

Initial test of MITA/DIMM with an operational CBP system

The MITA (Motion Imagery Task Analyzer) project was conceived by CBP OA (Customs and Border Protection - Office of Acquisition) and executed by JHU/APL (Johns Hopkins University/Applied Physics Laboratory) and CERDEC NVESD MSD (Communications and Electronics Research Development Engineering Command Night Vision and Electronic Sensors Directorate Modeling and Simulation Division). The intent was to develop an efficient methodology whereby imaging system performance could be quickly and objectively characterized in a field setting. The initial design, development, and testing spanned a period of approximately 18 months with the initial project coming to a conclusion after testing of the MITA system in June 2017 with a fielded CBP system. The NVESD contribution to MITA was thermally heated target resolution boards deployed to support a range close to the sensor and, when possible, at range with the targets of interest. JHU/APL developed a laser DIMM (Differential Image Motion Monitor) system designed to measure the optical turbulence present along the line of sight of the imaging system during the time of image collection. The imagery collected of the target board was processed to calculate the in situ system resolution. This in situ imaging system resolution and the time-correlated turbulence measured by the DIMM system were used in NV-IPM (Night Vision Integrated Performance Model) to calculate the theoretical imaging system performance. Overall, this proves the MITA concept feasible. However, MITA is still in the initial phases of development and requires further verification and validation to ensure accuracy and reliability of both the instrument and the imaging system performance predictions.

Overcoming shadowing and occlusion in imagery with error-resilient processing

Due to the delay of sequential 3-D Lidar image acquisition while an uncooperative human target is in motion, the image may generate missing or occlusion pixels. We wish to minimize the impact of image acquisition of a moving target for aided target recognition. We apply the standard Fourier transform algorithms for an error resilience restoration to minimize the impact to the Human Visual System (HVS) which tends to overly emphasize the edge and the artificially generated discontinuity in missing pixels. We compared (i) classical phase retrieval scheme: Gerchburg-Saxon-Hayes-Papoulis (GSHP) and (ii) the Compressive Sensing scheme: Candes-Romberg-Donohoe-Tao (CRDT). The following two lessons were learned: The mechanism is based on Gibbs overshooting of a step-discontinuity. It is based on relocating the sparsely sampled zeros at missing pixel locations a la spatial and spatial frequency inner product conformal mapping property.

Handheld threat object identification performance of 2D visible imagery versus 3D visible imagery

The objective of this research was to determine if there was an improvement in human observer performance, identifying potential weapons or threat objects, when imagery is presented in three dimensions instead of two dimensions. Also it was desired to quantify this potential improvement in performance by evaluating the change in N50 cycle criteria, for this task and target set. The advent of affordable, practical and real-time 3-D displays has led to a desire to evaluate and quantify the performance trade space for this potential application of the technology. The imagery was collected using a dual camera stereo imaging system. A series of eight different resolutions were presented to observers in both two and three dimensional formats. The set of targets consisted of twelve hand held objects. The objects were a mix of potential threats or weapons and possible confusers. Two such objects, for example, are a cellular telephone and a hand grenade. This target set was the same target set used in previously reported research which determined the N50 requirements for handheld objects for both visible and infrared imagers.