Adaptation of video moiré techniques to undersea mapping and surface shape determination

We have developed a system which confirms the identity of an object based on its three-dimensional surface shape. The system's two key elements are a computer routine which manipulates a desired two-dimensional output pattern and a light projector which illuminates test objects with this pattern.The operation of the system is based on prior knowledge of the surface shape for the object of interest, as determined by a previously developed machine vision system. A projection pattern is chosen to be the identifying cue to the observer for that object. For example, a set of parallel lines, a circle, or the word "pass" could all be used to signify that a particular object is being examined. This pattern is then distorted by the computer in a way which is determined by the surface shape data and projection and viewing angles for the system. This new pattern is, in a sense, an encrypted form of the original pattern. Only the original object holds the key to "undistorting" this projection pattern so that it may take on its original form. Any other object placed into the system to be examined only further distorts the pattern. Thus, by examining the projected patterns on objects being inspected, an object of interest can be distinguished from others.The simplicity of this system gives it potential for inspection and security applications in which the key issue may not be the actual surface shape, but rather a quick verification of an object's or person's identity.

show abstract

“…x x= cos(c) (1) where x' is the grid spacing in the projection plane and x is the grid spacing in the viewing plane (i.e. the xyplane.)…”

Section: Theory Of Operationmentioning

confidence: 99%

<title>Design of arbitrary projection patterns for object recognition</title>

1994

Self Cite

View full text Add to dashboard Cite

show abstract

“…Object range and plane orientation measurements have been obtained using laser patterns projected onto the target (Caimi and Tusting 1988;Davis and Tusting 1991). Interference methods using video moiré techniques have been utilized to provide higher resolution for underwater mapping and surface shape determination, although they require additional instrumentation to determine target range (Caimi et al 1993;Blatt et al 1992). Other interference methods have included holographic systems (Carder et al 1982;Katz et al 1984;Katz et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Development of a New Underwater Bathymetric Laser Imaging System: L-Bath

Moore¹,

Jaffe²,

Ochoa³

2000

J. Atmos. Oceanic Technol.

View full text Add to dashboard Cite

The design, construction, and performance of a new high-resolution underwater bathymetric prototype system (L-Bath) with extended imaging capability is presented. The design offers simultaneous reflectance and depth information on a pixel-by-pixel basis so that high-resolution reflectance and bathymetric maps of underwater targets can be provided with exact registration. The design supports operation in shallow coastal waters under daylight conditions where high turbidity and the influence of ambient backscatter are particularly limiting for underwater imaging systems. Its configuration is similar to existing laser line scanning systems but uses a pulsed laser for the source and a fixed field-of-view high-resolution linear charge-coupled device (CCD) as receiver. The pulsed laser allows short camera integration times, thereby reducing the influence of the ambient daylight signal, and the fixed field of view of the detector provides a precision nonmoving multielement receiver with imaging capability. As the laser sweeps across the field of view of the CCD, the position and signal strength of each laser target spot is imaged, permitting a measure of bathymetry and reflectance. Using the CCD, a highresolution slice through the reflected target spot radiance distribution is imaged so that system resolution can exceed the target spot size. The image of the target spot radiance distribution, modified by in-water scattering and target reflectance, provides new opportunities for image manipulation compared to typical underwater laser line scanning based systems. The simultaneous acquisition of reflectance and bathymetric maps permits discrimination capability between real objects of relief from scene reflectance variations.

show abstract