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13 Cards in this Set
- Front
- Back
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What are the visual illusions?
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False Horizon-- Cloud formations confused for ground/horizon
Flicker vertigo-- 4-20 cycles per second causes a reaction Fascination Fixation-- Target hypnosis Confusion with ground lights-- confuse ground lights with stars Relative Motion-- perceive other persons movement as yours (like at a stop light) Autokinesis-- Stare at a light for 8-10 seconds it starts to move Structural Illusion-- Window/heat waves/rain can distort vision Height /Depth perception-- flying over a low contrast environment (desert/water) can perceive details/height Size-distance-- Brighter=bigger Altered Plane of reference-- approaching a mountain you feel you need to climb (look at fat bob) Reversible perspective-- right red returning Crater illusion-- turn on search light in low light/sand/dust and creates a crater feeling |
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What are the three types of vision?
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Photopic-- highest acuity, mostly cone based during daylight hours, rhodopsin bleached out and less effective
Mesopic-- Dusk/Dawn, less acuity, color perception is reduced, start seeing loss of visual centers Scotopic-- night time, 20/200 vision, rod based no cones, no color vision, using peripheral and off-center vision/scanning, |
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What are the monocular depth and distance estimation techniques?
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Geometric prospective:
Linear Perspective-- converging lines as distance increases Apparent foreshortening-- shape of object is elliptical when viewed from side Vertical position in field-- higher=further away Retinal Image Size: Known image size-- larger an object on retina the closer and you are familiar with object size Increasing/Decreasing size Terrestrial association-- compare object to a known size object to determine size/distance Overlapping-- object overlapping is closer Aerial Perspective: Variations in color/shade-- subtle variations means you are closer Loss of detail/texture-- details become less apparent and illumination helps increase detail and texture at night Position of light/shadows Motion parallax-- Most important, closer go by paster and further are slower |
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How long does it take to dark adapt normally? After using an I2 device? After a bright light?
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30-45 minutes (increases 10,000 fold in first 30 minutes, lower the initial light level the faster it takes)
2-3 minutes 5-45 minutes, depends on brightness and duration. Muzzle flash not as big of a deal |
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What is the physiological blind spot?
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Present at all times. Results from position of optic disk (optic nerve) on retina. It has no light-sensitive receptors. The spot is 5.5 by 7.5 degrees and is located 10-15 degrees from the fovea.
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What is the night blind spot?
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This is caused by the lack of RODS in the fovea centralis. It is 5-10 degrees large
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What is the FOV for NVGs? What is your acuity with them?
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40 degrees
20/25 |
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What is BMNT? EENT?
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BMNT-- Before sunrise solar light becomes usable when the sun is below 12 degrees on horizon.
EENT-- Solar ambient light becomes unusable when the sun is below 12 degrees on the horizon at night |
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What are the NVG operational defects?
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Shading
Edge Glow Emission Points (glow even when covered) Flickering/Flashing/Intermittent operation |
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What are the NVG cosmetic blemishes?
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Bright Spots
Black Spots Image Distortion Image Disparity Fixed Pattern Scan Chicken Wire Output Brightness Variation |
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How do you achieve OSAP?
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Optimal Sight Adjustment Point
Need a 1/4 to 1/2 moon and set all settings to zero Adjust vertical adjust to see a full circle Adjust fore/aft adjustment by closing one eye and looking for edge to blur then adjust eye span in direction of blur Turn 1/2 turn closer to adjust for shifts in flight |
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How do you focus NVGs?
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OBJ Ring fully counterclockwise
Eye Focus Ring to 0 Look at something 100-200 feet away and cover one eye (not close) Turn OBJ ring until sharp image Turn focus until sharp, slight blur, then back again Do other eye Turn one OBJ ring out of focus and with both eyes open fine tune each tube |
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What does the low battery light indicate on the NVG battery pack?
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Less than 30 minutes left
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