Imaging lidar system for shallow and coastal water
First Claim
1. An apparatus for detecting and imaging from an airborne platform an object at least partially enveloped by water, the water having a surface and a bottom, comprising:
- pulsed light source generating means for selectively generating pulses of light from the airborne platform;
projecting means for projecting said pulses of light toward the water and at an object enveloped by the water;
bottom detector means for measuring the distance between the surface and the bottom of the water defining total water depth;
camera means for detecting said pulses of light reflected back from said object, said camera means being gated open after a selected time delay corresponding to the roundtrip propagation time of said light pulses to and from said object;
compensating means for automatically compensating for variations in total water depth and platform altitude, said compensating means comprising computer means for calculating said selected time delay based on input data which includes the total water depth from said bottom detector means, said computer means inputting said selected time delay to said delay generator means; and
convening means for convening said detected pulses of light to a video image of said object.
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Abstract
An imaging lidar system for underwater applications is presented which is well suited for imaging and detecting underwater targets suspended above and on the bottom in shallow and coastal water. The present invention provides the capability for rapid and reliable search, detection, classification and localization of objects in the surf zone which may present hazards to navigation and utilization of coastal areas as well as undesirable effluents and biological fouling of underwater objects. The present invention provides an improved bottom tracker, improved ability to deal with brightness variation and surface glint, and computerized real time detection algorithms.
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Citations
10 Claims
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1. An apparatus for detecting and imaging from an airborne platform an object at least partially enveloped by water, the water having a surface and a bottom, comprising:
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pulsed light source generating means for selectively generating pulses of light from the airborne platform; projecting means for projecting said pulses of light toward the water and at an object enveloped by the water; bottom detector means for measuring the distance between the surface and the bottom of the water defining total water depth; camera means for detecting said pulses of light reflected back from said object, said camera means being gated open after a selected time delay corresponding to the roundtrip propagation time of said light pulses to and from said object; compensating means for automatically compensating for variations in total water depth and platform altitude, said compensating means comprising computer means for calculating said selected time delay based on input data which includes the total water depth from said bottom detector means, said computer means inputting said selected time delay to said delay generator means; and convening means for convening said detected pulses of light to a video image of said object. - View Dependent Claims (2, 3, 4, 5)
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6. A method for detecting and imaging from an airborne platform an object at least partially enveloped by water, the water having a surface and a bottom, comprising the steps of:
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generating means for selectively generating pulses of light from the airborne platform; projecting said pulses of light toward the water and at an object enveloped by the water; measuring the distance between the surface and the bottom of the water defining total water depth; detecting said pulses of light reflected back from said object using camera means, said camera means being gated open by input from delay generator means, said camera means being gated open after a selected time delay corresponding to the roundtrip propagation time of said light pulses to and from said object; automatically compensating for variations in total water depth and platform altitude by calculating said selected time delay based on input data which includes the total water depth from said bottom detector means; inputting said selected time delay to said delay generator means; and converting said detected pulses of light to a video image of said object. - View Dependent Claims (7, 8, 9, 10)
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Specification