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NASA NTRS1975

International Symposium on Remote Sensing of Environment, 10th, University of Michigan, Ann Arbor, Mich., October 6-10, 1975, Proceedings. Volumes 1 & 2

Topics treated include the application of a Fourier transform spectrometer to infrared remote sensing, the performance optimization of a satellite-borne thematic mapper, a data handling system to be integrated with a digital airborne multispectral scanner, infrared thermography for micro- and mesometeorological measurements, satellite interrogated data collection platforms for river and flood forecasting and the automatic measurement of sea surface temperature from a GOES satellite. Solar and atmospheric effects on satellite imagery derived from aircraft reflectance measurements, methods for determining haze levels from multispectral scanner data, restoration of Landsat images by discrete two-dimensional deconvolution and the automatic classification of aircraft and satellite multispectral images using mixed integer programming are also discussed. Individual items are announced in this issue.

Source record↗

NASA NTRS1975

Evaluation of ERTS multispectral signatures in relation to ground control signatures using a nested-sampling approach

The author has identified the following significant results. Ground measured spectral signatures of wavelength bands matching ERTS MSS were collected using a radiometer at several Californian and Nevadan sites, and directly compared with similar data from ERTS CCTs. The comparison was tested at the highest possible spatial resolution for ERTS, using deconvoluted MSS data, and contrasted with that of ground measured spectra, originally from 1 meter squares. In the mobile traverses of the grassland sites, these one meter fields of view were integrated into eighty meter transects along the five km track across four major rock/soil types. Suitable software was developed to read the MSS CCT tapes, to shadeprint individual bands with user-determined greyscale stretching. Four new algorithms for unsupervised and supervised, normalized and unnormalized clustering were developed, into a program termed STANSORT. Parallel software allowed the field data to be calibrated, and by using concurrently continuously collected, upward- and downward-viewing, 4 band radiometers, bidirectional reflectances could be calculated.

Lyon, R. J. P.↗

NASA NTRS1976

Image processing of galaxy photographs

New computer techniques for analyzing and processing photographic images of galaxies are presented, with interesting scientific findings gleaned from the processed photographic data. Discovery and enhancement of very faint and low-contrast nebulous features, improved resolution of near-limit detail in nebulous and stellar images, and relative colors of a group of nebulosities in the field are attained by the methods. Digital algorithms, nonlinear pattern-recognition filters, linear convolution filters, plate averaging and contrast enhancement techniques, and an atmospheric deconvolution technique are described. New detail is revealed in images of NGC 7331, Stephan's Quintet, Seyfert's Sextet, and the jet in M87, via processes of addition of plates, star removal, contrast enhancement, standard deviation filtering, and computer ratioing to bring out qualitative color differences.

Arp, H.↗

NASA NTRS1977

Galatry profile convolved with the Fabry-Perot instrument function

The physical conditions in laboratory gases and in the upper atmosphere of the planets, including earth, can be deduced from a measurement of the intensity and line profile of different radiating molecules. Because of the low pressures in the upper atmospheres, many molecular lines with small pressure-broadening coefficients are collisionally narrowed. These lines are resolvable with a Fabry-Perot interferometer. Analytical expressions are given relating the measured line intensity and profile to the true line intensity and profile. A deconvolution of the measured profile gives the parameters A, beta, and K characterizing the collisionally narrowed Galatry profile. General expressions for the nonideal interferometer are discussed, and, specifically, mirror defects and a limited detector aperture are treated.

Goorvitch, D.↗

NASA NTRS1977

Wave optics of the central spot in planetary occultations

The detection of a bright central spot during the occultation of epsilon Geminorum by Mars demonstrates that an exponentially-stratified planetary atmosphere can act as a lens providing very high resolution of distant objects (e.g., quasars, white dwarfs, and pulsars). The diffraction nature of the central occultation spot is investigated, with special reference to Mars and Venus. In practice, however, central occultations by these planets are seldom observable from the earth's surface, and spacecraft would have to be used to obtain a suitable orientation for observers. Further difficulties may be encountered in image deconvolution needed for extended objects, in location of the image of a true point source, and in compensation for peculiarities of planets and their atmospheres.

Hubbard, W. B.↗

NASA NTRS1977

The effects of the atmospheric point-spread 'seeing' function on spatially resolved spectra of Jupiter

We present the results of an analysis of the effects of atmospheric seeing and of instrumental spectral and spatial resolution on the observed variation of absorption-line profiles across the disk of Jupiter. The technique described may be applied equally well to the analysis of observations of any extended astronomical source. These results show the necessity of obtaining accurate point-spread-function information during the course of observations of this nature. We also point out that in order to avoid the uncertainties and ambiguities inherent in attempts at deconvolution of observational data, one must properly convolve the appropriate spatial and spectral resolution functions with the models being tested and then compare the results with the observational data.

Gelfand, J.↗

NASA NTRS1977

Research in Solar Physics: Analysis of Skylab/ATM S-056 X-Ray Data

Data obtained by the X-ray event analyzer are described as well as methods used for film calibration. Topics discussed include analyses of the 15 June 1973 flare, oscillations in the solar soft X-ray flux, and deconvolution of X-ray images of the 5 September 1973 flare.

Henze, W., Jr.↗

NASA NTRS1977

Class of near-perfect coded apertures

Coded aperture imaging of gamma ray sources has long promised an improvement in the sensitivity of various detector systems. The promise has remained largely unfulfilled, however, for either one of two reasons. First, the encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. Second, if the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. It is proposed to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method.

Cannon, T. M.↗

NASA NTRS1977

Multispectral data restoration study

A digital resampling technique for LANDSAT data is reported that incorporates a deconvolution concept to minimize spatial and radiometric degradation of data during resampling for geometric correction. A quantitative comparison of cubic convolution and digital restoration methods establishes the latter as the superior technique.

Shah, N. J.↗

NASA NTRS1978

Limb brightening on Uranus - The visible spectrum. II

A detailed analysis is presented of photoelectric area-scanning photometry of the Uranus disk obtained during the 1976 apparition. Coarse quantitative information on the true radial intensity distribution over the Uranus disk is derived in four selected wavebands. Lack of circular symmetry in the intensity distributions indicates the presence of disk structure, especially polar brightening, in each waveband. For the 6190-A CH4 band, the distribution corresponds to a uniform disk upon which a hint of polar brightening is superimposed. For the 6400-A region, moderate limb darkening is found. It is pointed out that the coarse analytical technique used in the analysis to explore the information content of the photometric scans of Uranus has several basic limitations. Direct deconvolution of the Uranus scans is required to thoroughly investigate the two-dimensional photometric structure of its disk.

Price, M. J.↗

NASA NTRS1977

Analysis of photographic X-ray images

Some techniques used to extract quantitative data from the information contained in photographic images produced by grazing incidence soft X-ray optical systems are described. The discussion is focussed on the analysis of the data returned by the S-054 X-Ray Spectrographic Telescope Experiment on Skylab. The parameters of the instrument and the procedures used for its calibration are described. The technique used to convert photographic density to focal plane X-ray irradiance is outlined. The deconvolution of the telescope point response function from the image data is discussed. Methods of estimating the temperature, pressure, and number density of coronal plasmas are outlined.

Krieger, A. S.↗

NASA NTRS1977

A hard X-ray imaging instrument for solar and cosmic sources

A hard X-ray imaging instrument is described which is capable of high-resolution imaging of solar and cosmic hard X-ray sources between 2 and 80 keV during Shuttle sortie flights. The properties of solar burst sources and the resulting instrument requirements are discussed. The instrument envelope of 1.2 x 1.2 x 3.0 meters includes a tungsten multigrid collimator which has 4-arcsec resolution, a 40-arcmin response envelope and a point-source effective area of 26 sq cm. A combination of periodic fan beams and nonperiodic pencil beams enables a unique deconvolution to be achieved within a 128 x 128 arcsec field without mechanical scanning. The detector system is a set of direct-readout 40 atm-cm xenon-filled proportional counters designed to minimize background. The instrument is capable of refurbishment to optimize the collimator configuration for specific solar or cosmic scientific objectives, to upgrade the angular resolution, or to extend the high-energy response.

Hurford, G. J.↗

NASA NTRS1978

Parameter estimation applied to Nimbus 6 wide-angle longwave radiation measurements

A parameter estimation technique was used to analyze the August 1975 Nimbus 6 Earth radiation budget data to demonstrate the concept of deconvolution. The longwave radiation field at the top of the atmosphere is defined from satellite data by a fifth degree and fifth order spherical harmonic representation. The variations of the major features of the radiation field are defined by analyzing the data separately for each two-day duty cycle. A table of coefficient values for each spherical harmonic representation is given along with global mean, gradients, degree variances, and contour plots. In addition, the entire data set is analyzed to define the monthly average radiation field.

Green, R. N.↗

NASA NTRS1979

Acceleration and transport of galactic cosmic rays

A recently proposed cosmic-ray acceleration mechanism is combined with a model of transport and loss from the Galaxy to construct a model for galactic cosmic rays. Various aspects of the cosmic-ray spectrum, including the secondary-to-primary ratio as a function of energy, are found to fit naturally into the overall picture. A solution to the dynamical-halo model with energy-dependent diffusion coefficient (kappa) is presented. This model is consistent with the observed spectra if kappa is proportional to the square root of the kinetic energy. The observed flattening of the secondary-to-primary ratio below about 1-2 GeV per nucleon is shown to be a natural consequence of the model. Similarly, the primary electron spectrum is predicted to flatten below about 1-2 GeV, which is consistent with deconvolution of the local nonthermal radio spectrum, although the flattening is not quite as much as indicated by the observations.

Jokipii, J. R.↗

NASA NTRS1978

Signal processing in ultrasound

Signal is the term used to denote the characteristic in the time or frequency domain of the probing energy of the system. Processing of this signal in diagnostic ultrasound occurs as the signal travels through the ultrasonic and electrical sections of the apparatus. The paper discusses current signal processing methods, postreception processing, display devices, real-time imaging, and quantitative measurements in noninvasive cardiology. The possibility of using deconvolution in a single transducer system is examined, and some future developments using digital techniques are outlined.

Le Croissette, D. H.↗

NASA NTRS1979

Calculation of total cross sections for charge exchange in molecular collisions

Areas of investigation summarized include nitrogen ion-nitrogen molecule collisions; molecular collisions with surfaces; molecular identification from analysis of cracking patterns of selected gases; computer modelling of a quadrupole mass spectrometer; study of space charge in a quadrupole; transmission of the 127 deg cylindrical electrostatic analyzer; and mass spectrometer data deconvolution.

Ioup, J.↗

NASA NTRS1979

Application of digital image processing techniques to astronomical imagery, 1979

Several areas of applications of image processing to astronomy were identified and discussed. These areas include: (1) deconvolution for atmospheric seeing compensation; a comparison between maximum entropy and conventional Wiener algorithms; (2) polarization in galaxies from photographic plates; (3) time changes in M87 and methods of displaying these changes; (4) comparing emission line images in planetary nebulae; and (5) log intensity, hue saturation intensity, and principal component color enhancements of M82. Examples are presented of these techniques applied to a variety of objects.

Lorre, J. J.↗

NASA NTRS1980

A plane-polar approach for far-field construction from near-field measurements

The planar configuration with a probe scanning a polar geometry is discussed with reference to its usefulness in the determination of a far field from near-field measurements. The accuracy of the method is verified numerically, using the concept of probe compensation as a vector deconvolution. Advantages of the Jacobi-Bessel series over the fast Fourier transforms for the plane-polar geometry are demonstrated. Finally, the far-field pattern of the Viking high gain antenna is constructed from the plane-polar near-field measured data and compared with the previously measured far-field pattern.

Rahmat-Samii, Y.↗