Engineering topics

Goetz, A. F. H.

Publications and source records attributed to Goetz, A. F. H..

At least 37 records · Page 2

NASA NTRS1985

Imaging spectrometry for earth remote sensing

Initial results of the novel remote earth sensing technique of imaging spectrometry, which is technically feasible from both spacecraft and aircraft platforms, indicate that the direct identification of surface materials on a picture-element basis is possible through proper sampling of absorption features in the reflectance spectrum. Sensors of this type are able to acquire images simultaneously in 100-200 contiguous spectral bands. Computerized data reduction and storage techniques are available for the large data sets thus generated, and novel analytic techniques are under development to maximize information content extraction.

Goetz, A. F. H.↗

NASA NTRS1985

Optical remote sensing of the earth

In the present assessment of the contributions of optical earth resources remote sensing in the 0.4-15.0 micron region, attention is given to underlying principles, applications to scientific disciplines such as geology, hydrology and oceanography, the recent development history of the requisite sensors, and sensor development trends. Development status characterizations are given for thematic mapping, modular optoelectronic multispectral scanning, the telescope/CCD 'SPOT' program of France, the thermal IR multispectral scanner for mineral signature identification, airborne imaging spectrometry, and the Advanced Visible and IR Imaging Spectrometer that is nearing deployment. Technology development trends and the capabilities they portend are projected.

Goetz, A. F. H.↗

NASA NTRS1984

Airborne imaging spectrometer - A new tool for remote sensing

The first of a new class of remote sensing instruments is described. The Airborne Imaging Spectrometer represents the first use of two-dimensional integrated infrared area arrays in a scientific application. The instrument images 32 cross-track pixels simultaneously, each in 128 spectral bands in the 1.2- to 2.4-micron region. The IFOV of the instrument is 1.9 mrad/pixel and the spectral sampling interval is 9.6 nm. Plans include upgrading the detector from the current 32 x 32 element HgCdTe CCD array to a 64 x 64 element array in 1985. Science and engineering data are currently being actively gathered with the instrument.

Vane, G.↗

NASA NTRS1984

High spectral resolution remote sensing of the land

Spectral remote sensing has been practiced on a large scale since the launch of Landsat 1 in 1972. The limited information contained in this spectrally undersampled data set has led to the development of sophisticated statistical-inferential methods for data analysis. The results are usually limited by the availability of ground truth information. Recent technological developments have made it feasible to create narrow-band, contiguous, spectral image data sets that make possible the identification of surface cover materials based on the complete reflectance spectrum for each picture element. This capability will revolutionize the use of remote sensing data and require new deterministic image processing techniques to extract the full information content from the data. Sensors, based on the concept of imaging spectrometry and the new technology of area array infrared detectors, have been constructed and are candidates for Shuttle and space platform flights.

Goetz, A. F. H.↗

NASA NTRS1983

Mineralogic information from a new airborne thermal infrared multispectral scanner

The thermal IR multispectral scanner (TIMS) has been developed for airborne geologic surveys. The resststrahlen band between 8-11 microns is exhibited by interatomic stretching vibrations of Si and oxygen bound up in the crystal lattice of silicate rocks. The crystal structure of the component minerals influence the depth and position of the detected band. The TIMS has six channels, an 80 deg field of view, and a sensitivity sufficient to detect a noise equivalent change in spectral emissivity of 0.002-0.006. The six bands measured are 8.2-8.6, 8.6-9.0, 9.4-10.2, 10.2-11.2, and 11.2-12.2 microns, using HgCdTe detectors. The data are analyzed with respect to emissivity variations as a function of wavelength, using the component transformation technique called a decorrelation stretch, with spectral differences being displayed as different colors. Sample scenes from Death Valley and the Nevada Cuprite mining district are compared with visible and near-IR color composites of the same areas, revealing the superior distinctions that are available with the TIMS.

Kahle, A. B.↗

NASA NTRS1983

Remote sensing for exploration - An overview

The use of remote sensing in resource exploration is reviewed, with emphasis placed on new developments in high spectral resolution remote-sensing techniques for mineralogic and vegetation mapping. Topics discussed include aerial photography and satellite remote sensing, concepts and principles of spectral data collection, spectral properties of rocks and minerals, spectral properties of vegetation, and botanical aspects of geochemical stress. The discussion also covers applications of Landsat multispectral scanner data to lithologic and geobotanic studies and the future development of data acquisition and data interpretation techniques.

Goetz, A. F. H.↗

NASA NTRS1983

Identification of hydrothermal mineralization in Baja California, Mexico from orbit using the Shuttle multispectral infrared radiometer

Data from the Space Shuttle Multispectral IR Radiometer (SMIRR), which is a 10-channel remote sensor designed to record narrow band spectral data in the 0.5-2.4 micron wavelength range, were used to identify and study a previously unreported area of hydrothermal alteration on the Baja California peninsula. Absorption at 2.17 microns, which is diagnostic of the minerals pyrophyllite, dickite, and alunite, was observed in many spectra and the presence of pyrophyllite and dickite was confirmed by X-ray diffraction analysis of field samples. Anomalously high Mo, B, Sn, Zr, and Ag were found in three samples.

Rowan, L. C.↗

NASA NTRS1983

Airborne imaging spectrometer - A new tool for remote sensing

The first of a new class of remote sensing instruments is described. The Airborne Imaging Spectrometer represents the first use of two-dimensional area arrays in a scientific application. The instrument images 32 cross-track pixels simultaneously, each in 128 spectral bands in the 1.2 to 2.4 micro region. The IFOV of the instrument is 1.9 mrad and the spectral sampling interval is 9.6 nanometers. Plans include upgrading the detector from the current 32 x 32 element HgCdTe CCD array to a 64 x 64 element array in 1984. Science and engineering data are currently being actively gathered with the instrument.

Vane, G.↗

NASA NTRS1983

An imaging spectrometer experiment for the Shuttle

An imaging spectrometer experiment concept for earth remote sensing, developed as part of NASA's Multispectral Linear Array program, will map a series of test sites at high spatial and spectral resolution from the vantage point of the Shuttle payload bay. The instrument covers the spectral range from 0.4 to 2.5 micrometers with a sampling interval of 10 nanometers in the visible and near infrared (to 1.0 micrometer) and 20 nanometers in the short wavelength infrared (1.0 to 2.5 micrometers). Resolution corresponding to a ground instantaneous field of view (pixel size) of 30 meters is provided over a swath width of 12 kilometers. On-board data editing is utilized to select a subset of the data stream for transmission to the ground. The instrument utilizes silicon and mercury cadmium telluride area array detectors. Pointing mirrors are included to permit specific test sites to be imaged from the Shuttle orbit.

Wellman, J. B.↗

NASA NTRS1983

Imaging systems for the delineation of spectral properties of geologic materials in the visible and near-infrared

The current status of imaging systems for the identification of the spectral properties of geologic minerals in the visible and near infrared ranges is reviewed. The technical characteristics of the most important instruments are given, including the MSS and TM, the Airborne Imaging Spectrometer, (AIS) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), and the Shuttle Imaging Spectrometer Experiment (SISEX). It is pointed out that none of the current systems have sufficient spectral resolution to identify mineralogy on the basis of absorption characteristics in the visible, near-infrared or shortwave-infrared bands. The development of new systems with higher spectral resolution is discussed.

Marsh, S. E.↗

NASA NTRS1983

A Shuttle Imaging Spectrometer Experiment for the late 1980's

The Shuttle Imaging Spectrometer Experiment (SISEX), proposed as a next experimental step in the development of advanced earth remote sensing technology, is capable of imaging the earth's surface simultaneously in 128 spectral bands covering the range from 0.4 to 2.5 micrometers. Laboratory and field measurements have suggested the utility of high-spectral-resolution remote sensing, and an aircraft-borne precursor to the SISEX has demonstrated the ability to distinguish among differing vegetation and rock types - in certain cases making unique identifications. The SISEX instrument utilizes an area-array focal plane, populated by visual- and infrared-sensitive detectors, to acquire simultaneous spatial and spectral information on a line-by-line basis. The spectrum is dispersed by means of a prism spectrometer. The performance analysis indicates that the scientific requirements for radiometric precision can be achieved using optics with an effective circular aperture of 11 cm.

Wellman, J. B.↗

NASA NTRS1982

Mineral identification from orbit - Initial results from the Shuttle multispectral infrared radiometer

The Shuttle multispectral IR radiometer (SMIRR) was designed to obtain surface reflectance data in ten spectral bands in order to evaluate the usefulness of a future imaging system for remote mineral identification. Attention was given to the 2.0-2.4 micron region, which has a wealth of spectral absorption features and appeared to have potential for the identification of CO3- and OH-bearing minerals such as the kaolinite and montmorillonite clays. SMIRR radiances were normalized by using a spectrum for dune sand collected in the Kharga Depression in Egypt. Direct identifications have been made of kaolinite-containing and carbonate material, indicating an exceptional potential for future orbital platform narrowband spectral imaging systems for mineralogical mapping.

Goetz, A. F. H.↗

NASA NTRS1982

Portable Radiometer Identifies Minerals in the Field

Hand-held optical instrument aids in identifying minerals in field. Can be used in exploration for minerals on foot or by aircraft. The radiometer is especially suitable for identifying clay and carbonate minerals. Radiometer measures reflectances of mineral at two wavelengths, computes ratio of reflectances, and displays ratio to user.

Goetz, A. F. H.↗

NASA NTRS1982

Radiometric considerations in remote sensing systems

All sensors systems designed to acquire quantitative data undergo radiometric calibration. The types and potential accuracies of calibration are discussed as well as the needs for calibration in the practical application of sensors. The recent and ongoing experience with the shuttle multispectral infrared radiometer is used as a reference.

Goetz, A. F. H.↗

NASA NTRS1982

Shuttle Multispectral Infrared Radiometer - Preliminary results from the second flight of Columbia

The Shuttle Multispectral Infrared Radiometer (SMIRR) is a spectroradiometer covering the region 0.5-2.5 microns in 10 channels that acquired data from 100 m diameter spots along the subspacecraft ground track. It was flown aboard the second flight of the Space Shuttle Columbia, November 12-14, 1981. Preliminary analysis of data from one of the 17 orbits covered shows that in Egypt, carbonate rocks, kaolinite, and possibly montmorillonite can be identified by their SMIRR spectral signatures in conjunction with limited knowledge of the regional geologic setting. The SMIRR data have made possible the first remote identification of carbonate rocks and clays from orbit.

Goetz, A. F. H.↗

NASA NTRS1981

Geologic remote sensing

Remote-sensing techniques based on the analysis of spectral reflectance, spectral emittance, thermal inertia, and radar measurements are reviewed. Specific applications of Landsat multispectral scanner are examined with emphasis on mineral exploration. The potential of satellite systems for detailed lithologic mapping is pointed out.

Goetz, A. F. H.↗

NASA NTRS1981

A data base of geologic field spectra

It is noted that field samples measured in the laboratory do not always present an accurate picture of the ground surface sensed by airborne or spaceborne instruments because of the heterogeneous nature of most surfaces and because samples are disturbed and surface characteristics changed by collection and handling. The development of new remote sensing instruments relies on the analysis of surface materials in their natural state. The existence of thousands of Portable Field Reflectance Spectrometer (PFRS) spectra has necessitated a single, all-inclusive data base that permits greatly simplified searching and sorting procedures and facilitates further statistical analyses. The data base developed at JPL for cataloging geologic field spectra is discussed.

Kahle, A. B.↗

NASA NTRS1981

Spectroscopic remote sensing for geological applications

Remote sensing is being used with increasing frequency in the development of geologic maps and in the exploration process. Spectral data from airborne and spaceborne multispectral scanners provide information on rock type and vegetation stress, important in geologic applications. Emphasis is now being placed on direct identification of materials rather than discrimination among geologic units. To do this, higher spectral resolution systems with wider spectral coverage than currently available are required. Imaging spectroscopy in the 0.4 - 14 microns region appears to be the answer.

Goetz, A. F. H.↗