Passive millimeter-wave imagery of helicopter obstacles in a sand environment

Wikner, David A.

doi:10.1117/12.669170

Cited by 11 publications

(12 citation statements)

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“…1. Extracts of measured imagery in the horizontal polarization from [50] showing the (a) boulder, (b) cinder blocks, and (c) wooden post with the octahedral metal cross. Black denotes radiometrically 'hot.'…”

Section: Modeled Outdoor Scenes Compared With Experimentally Acqumentioning

confidence: 99%

“…The helicopter benefits from a PMMW imager as situational awareness is required in visually degraded environments, such as landing in fog or rotor down-thrust-induced dust storms (referred to as brownout), when in close proximity to obstacles [48]. Some excellent quantitative experimental measurements of such obstacles have been made [50] in clear weather that can be used in the partial validation of scene simulation. Obstacles measured in this paper were cinder blocks, a boulder, a vertically standing wooden post, and an octahedral metal cross, all located on a sand base with an asphalt road to the right-hand side.…”

Section: A Helicopter Landing Scenariomentioning

confidence: 99%

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Outdoor Passive Millimeter-Wave Imaging: Phenomenology and Scene Simulation

Salmon

2018

IEEE Trans. Antennas Propagat.

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A model for scene simulation is presented, which describes quantitatively the recognized phenomenology of passive millimeter-wave (PMW) imaging in land, sea, and air scenarios. The model describes objects in a scene as facets giving them electromagnetic properties from their electrical permittivities. This enables polarimetric effects in scenes to be reproduced. Illumination from the sky and ground is calculated using radiation transport, as are the emissive and absorbing effects of the atmosphere between the objects and the imager. The model includes the effects of image sampling, diffraction effects of finite imager aperture sizes, and system noise. Phenomena in experimentally acquired images in the 94 GHz atmospheric transmission window are quantified from three scenarios. These are a helicopter landing site as viewed by the pilot, a coastal region showing boats, land and buildings viewed from sea level, and an airfield viewed from directly above. These are compared quantitatively to the simulated scenes from these scenarios, finding agreement between the radiation temperatures to within a few degrees kelvin. These discrepancies are accounted for by the uncertainties in the permittivities of materials in the scene. This paper constitutes the partial validation of a scene simulation capability for PMMW imaging in outdoor scenarios.

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Section: Modeled Outdoor Scenes Compared With Experimentally Acqumentioning

confidence: 99%

Section: A Helicopter Landing Scenariomentioning

confidence: 99%

Outdoor Passive Millimeter-Wave Imaging: Phenomenology and Scene Simulation

Salmon

2018

IEEE Trans. Antennas Propagat.

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“…In both cases the results were encouraging but it was clear further work needed to be done. There has now been a great deal of data collection including polarimetric data of scenes [11][12][13] , dust 14 , skin 15 plus many others and our understanding of materials in the millimeter and sub-millimeter wave region has greatly improved. Modeling has also improved considerably, benefitting from high power computers and digital cinematography giving rise to realistic models of objects, people and scenes.…”

Section: Modeling and Phenomenologymentioning

confidence: 99%

Millimeter wave imaging: a historical review

2017

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The SPIE Passive and Active Millimeter Wave Imaging conference has provided an annual focus and forum for practitioners in the field of millimeter wave imaging for the past two decades. To celebrate the conference's twentieth anniversary we present a historical review of the evolution of millimeter wave imaging over the past twenty years. Advances in device technology play a fundamental role in imaging capability whilst system architectures have also evolved. Imaging phenomenology continues to be a crucial topic underpinning the deployment of millimeter wave imaging in diverse applications such as security, remote sensing, non-destructive testing and synthetic vision.

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“…• Despite good sensor thermal resolution/sensitivity (<0.3 K), the ditch was barely visible as a dark line across the image. The berm was also very difficult to detect (14).…”

Section: Scenario B: Landing/takeoff Obstacle Avoidancementioning

confidence: 99%

Millimeter-Wave and Submillimeter-Wave/Terahertz Passive Imaging System Requirements: A Phenomenological Perspective

Murrill¹

2013

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Passive millimeter-wave imagery of helicopter obstacles in a sand environment

Cited by 11 publications

References 1 publication

Outdoor Passive Millimeter-Wave Imaging: Phenomenology and Scene Simulation

Outdoor Passive Millimeter-Wave Imaging: Phenomenology and Scene Simulation

Millimeter wave imaging: a historical review

Millimeter-Wave and Submillimeter-Wave/Terahertz Passive Imaging System Requirements: A Phenomenological Perspective

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