Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Reexamination Certificate
2001-03-02
2004-07-06
Smith, Zandra V. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
C356S326000
Reexamination Certificate
active
06760106
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to multispectral, hyperspectral, and ultraspectral imagery, and more particularly to formation of spatially correct spectral two dimensional spectral images from stored digital single dimensional images by digital manipulation of stored data. In the preferred embodiment, single dimensional images of a selected spectral band are correlated to their respective geometric locations by referring to linked two dimensional images having a plurality of geometric reference points, and are subsequently assembled into a single, two dimensional image of the selected spectral band.
2. Description of the Prior Art
Aerial imagery provides a specialized technique of obtaining information regarding characteristics of large land masses which may be unavailable from other sources or inefficiently obtained in other ways. In some image acquisition processes, images are arranged or taken by layers of information. Such images have equivalent geographic coverage, but capture different characteristics. For example, multispectral or hyperspectral imagery includes layers of data taken at different frequency bands. Each image data layer conveys different information to the observer. In the example of forest fires, images derived only from visible portions of the spectrum may reveal only a cloudy smoke cover. However, images based on infrared bands may reveal underlying conditions including flame front lines. In agriculture, to consider a second example, health of a crop, as reflected by sparseness or thickness of foliage, may be quantified to determine where certain nutrients or water are deficient or overabundant.
Successful sequential imagery, particularly wherein bounds of one image abut bounds of surrounding images, is dependent upon appropriate attitude of the image acquiring device. Low altitude multispectral, hyperspectral, and ultraspectral imagery, that being imagery acquired from a camera or other image gathering apparatus carried aboard an air breathing aircraft, is especially subject to various problems which may arise from attitude of the aircraft. A notorious obstacle to taking sequential single dimensional or line images from aircraft is variation in any of pitch, roll, and yaw of the aircraft due to air currents, internal vibration, and other causes. As pitch, roll, and yaw vary, each succeeding imaging location varies from a desired constant orientation, such as directly below the aircraft. Consequently, captured images may not be sufficiently aligned with previously captured images as to display sufficient continuity of the subject to render useful information. In “push broom” multispectral, hyperspectral, and ultraspectral scanning, the location of images varies from the usual focal point directly below the aircraft with aircraft movement.
In aerial photography, a frequent answer has been to stabilize a camera within the aircraft with respect to the ground so that the camera maintains vertical orientation despite variations in pitch, roll, and yaw. This approach has been satisfactory when the aircraft is fairly large. That is to say, conventional manned aircraft usually have sufficient space, strength, and power to accommodate stabilizing apparatus. U.S. Pat. No. 4,764,781, issued to Kenneth G. Leib et al. on Aug. 16, 1988, exemplifies camera stabilization.
However, stabilizing apparatus precludes the use of miniature aircraft, where “miniature” encompasses aircraft too small to accommodate a human pilot. In some situations, only miniature aircraft may be practical to use. Even where larger aircraft are employed, it may be preferable to conserve space, weight, and expense, among other resources. A need exists for much smaller apparatus that will solve the problem of image alignment.
Capture of images in digital form and manipulation of digital data may be exploited to render stabilizing apparatus unnecessary. Digital apparatus is sufficiently small as to reduce requirements for space, weight, complexity and reliability, and expense in aerial imagery acquisition. Correlation techniques applicable to digitized images are known. However, many correlation techniques are not susceptible to single dimensional images typical of images acquired by “push broom” hyperspectral scanners because it is necessary to have a minimum of three non-collinear points to establish reference data from two dimensional images. No satisfactory way to manipulate single dimensional images exists to establish accurate location in two dimensions.
One approach is to generate several images simultaneously from a common source. This approach is employed in holography and other optical disciplines. U.S. Pat. No. 3,586,434, issued to Peter F. Mueller on Jun. 22, 1971, shows use of a beam splitter in multispectral image storage.
U.S. Pat. No. 5,619,596, issued to Tadao Iwaki et al. on Apr. 8, 1997 shows a correlation technique that overcomes motion of an input image.
U.S. Pat. No. 5,327,286, issued to Jeffrey B. Sampsell et al. on Jul. 5, 1994, describes an optical correlation system employing a beam splitter to derive two images, and a microprocessor to process corresponding data.
U.S. Pat. No. 5,061,063, issued to David P. Casasent on Oct. 29, 1991, presents a technique wherein a single dimension image is compared to a two dimensional image.
U.S. Pat. No. 6,160,910, issued to Daniel Freifeld on Dec. 12, 2000, shows an optical system for providing images of sufficient quality to derive accurate measurements from the same.
The prior art fails to show a system wherein a single dimensional image and a two dimensional image are generated simultaneously from a single optical input, are digitized, and wherein a two dimensional image is reconstituted from a digital record of many single dimensional images, using geometric reference points taken from the two dimensional image to establish correct location of each single dimensional image within the reconstituted image.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention sets forth novel apparatus for and method of registering a single dimensional image or simultaneously collected series of spectrally unique single dimensional images to a two dimensional image, and of generating two dimensional images, preferably of a selected spectral band, from stored digital single dimensional images by digital manipulation of stored data. Single dimensional images of a selected spectral band are correlated to their respective geographic locations by referring to linked two dimensional images having a plurality of geographic reference points, and are assembled into a single, two dimensional image of the selected spectral band.
The foregoing is accomplished by processing optical images to generate two images simultaneously. A light beam conveying a desired image, which will be termed a primary image, is split into two images. One of these two images is passed through a slit to generate a single dimensional image, and preferably is also divided into spectral bands, which process yields a number of single dimensional images differing only in their spectral bands. The other image, which will be termed a reference image, is retained in two dimensional format, and includes a plurality of at least three recognizable geographic reference points. All images, wherein each primary image yields one reference image and potentially many single dimensional images or line scans each of one spectral band, are stored digitally, and are digitally linked to one another. This process is repeated for each sequential primary image.
A two dimensional image of a selected spectral band is subsequently reconstituted from the many single dimensional images which have been digitally stored. Each single dimensional image or line is placed digitally in an array corresponding to the primary image. Each line is correctly located by referring to its linked reference image. The reference image includes at least three
Banner David L.
Smith Zandra V.
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