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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Application of thematic mapper-type data over a porphyry-molybdenum deposit in Colorado

The objective of the study was to evaluate the utility of thematic mapper data as a source of geologically useful information for mountainous areas of varying vegetation density. Much of the processing was done in an a priori manner without prior ground-based information. This approach resulted in a successfull mapping of the alteration associated with the Mt. Emmons molybdenum ore body as well as several other hydrothermal systems. Supervised classification produced a vegetation map at least as accurate as the mapping done for the environmental impact statement. Principal components were used to map zones of general, subtle alteration and to separate hematitically stained rock from staining associated with hydrothermal activity. Decorrelation color composites were found to be useful field mapping aids, easily delineating many lithologies and vegetation classes of interest. The factors restricting the interpretability and computer manipulation of the data are examined.

Rickman, D. L.↗
NASA NTRS1984

Application of the Tasseled Cap concept to simulated thematic mapper data

Thematic Mapper signal counts in the six reflective bands (i.e., excluding the thermal band) are simulated using field and laboratory spectrometer measurements of a variety of crops, crop conditions, and soil types. The Dave atmospheric model and prelaunch sensor characteristics comprise the other components of the simulation. The simulated data are found to occupy essentially three dimensions, two of which are equivalent to the MSS Tasseled Cap Greennes and Brightness features, and a third which is substantially influenced by the mid-infrared bands of the TM. This new dimension is primarily related to soil characteristics, including soil moisture. The nature and characteristics of each dimension are discussed, as are some of the expected information gains (over MSS data) resulting from the additional dimensionality of the data.

Crist, E. P.↗
NASA NTRS1984

Thematic Mapper image quality - Registration, noise, and resolution

The Landsat-4 satellite has two new imaging radiometers, including the redesigned Multispectral Scanner (MSS) and the Thematic Mapper (TM). The present investigation is concerned with an assessment of TM image quality on the basis of a study of band-to-band registration, periodic noise, and spatial resolution. In the TM images analyzed, the band-to-band registration accuracy of the instrument is very good. A few imperfections were found. Once a stable misregistration is removed, the TM should also meet its registration specifications between focal planes. Spatial resolution analyses in terms of MTF were performed in comparison modes. The forward and backward scans were shown to have virtually identical MTFs.

Wrigley, R. C.↗
NASA NTRS1984

Comparison of the information content of data from the Landsat-4 Thematic Mapper and the Multispectral Scanner

There has been a steady increase with respect to the available capability to monitor the earth's surface from satellite platforms. Developments regarding instrumentation should now be considered in the context of the possible commercialization of space systems. The satellite data user is to select his data with many variables in mind, including cost. The present investigation provides a statistical comparison of simultaneously acquired data from the Landsat-4 Thematic Mapper (TM) and the Multispectral Scanner (MSS) for five scenes acquired over agricultural areas. Simple examination of photographic products and manipulation and display of image data suggests that the utility of the TM data will be far greater than that of the MSS. However, factors of cost and frequency of observations can also be important. The approach employed in the investigation should facilitate evaluation of future remote sensing systems.

Price, J. C.↗
NASA NTRS1984

An analysis of Landsat-4 Thematic Mapper geometric properties

Landsat-4 Thematic Mapper data of Washington, DC, Harrisburg, PA, and Salton Sea, CA were analyzed to determine geometric integrity and conformity of the data to known earth surface geometry. Several tests were performed. Intraband correlation and interband registration were investigated. No problems were observed in the intraband analysis, and aside from indications of slight misregistration between bands of the primary versus bands of the secondary focal planes, interband registration was well within the specified tolerances. A substantial number of ground control points were found and used to check the images' conformity to the Space Oblique Mercator (SOM) projection of their respective areas. The means of the residual offsets, which included nonprocessing related measurement errors, were close to the one pixel level in the two scenes examined. The Harrisburg scene residual mean was 28.38 m (0.95 pixels) with a standard deviation of 19.82 m (0.66 pixels), while the mean and standard deviation for the Salton Sea scene were 40.46 (1.35 pixels) and 30.57 m (1.02 pixels), respectively. Overall, the data were judged to be a high geometric quality with errors close to those targeted by the TM sensor design specifications.

Walker, R. E.↗
NASA NTRS1984

A statistical evaluation of the advantages of Landsat Thematic Mapper data in comparison to Multispectral Scanner data

On July 16, 1982, the second decade of land remote sensing from space was inaugurated with the successful launch of Landsat-4. This satellite carries the Multispectral Scanner (MSS) and a new sensor, the Thematic Mapper (TM). The TM represents the result of an effort in which all of the major improvements in remote-sensing capability were simultaneously integrated into one system. An experiment was developed and conducted to quantify the effect of each TM sensor parameter on classification accuracy. This paper discusses the experimental design and summarizes the results obtained using TM data acquired over the Washington, DC area on November 2, 1982. Attention is given to a study site/data description, the experimental design, photointerpretation and digitization, spectral simulation, radiometric simulation, and spatial simulation.

Williams, D. L.↗
NASA NTRS1984

Evaluation of Thematic Mapper for detecting soil properties under grassland vegetation

Analysis of Thematic Mapper data acquired November 15, 1982, over a vegetated site located in the East Texas Timberlands and Claypan area of Texas has indicated that montmorillonitic clay textured soils can be separated from soils with different textures. The difference of TM band 4 (0.76-0.90 micron) and band 7 (2.08-2.35 microns) had an agreement of 55.8 percent with the USDA soil survey for upland clay soils. This compared to 55.9-percent agreement when all six bands (excluding the thermal) were used. The disagreement occurred at the boundary lines as defined by the USDA soil survey and the spectral data. This result is considered to be fairly good, considering the difficulty in placement of soil boundaries by the soil scientist in the field. While the exact influence on the vegetation, and thus the spectral response observed by TM, is not understood at this time, it appears that TM band 7 is responding to the type of mineralogy of the soil and that soil properties important to the plant can be detected using TM.

Thompson, D. R.↗
NASA NTRS1984

Snow reflectance from Landsat-4 Thematic Mapper

In California 75 percent of the agricultural water supply comes from the melting Sierra Nevada snowpack. Basin-wide spectral albedo measurements from the Landsat-4 Thematic Mapper (TM) could be used to better forecast the timing of the spring runoff, because these data can be combined with solar radiation calculations to estimate the net radiation balance. The TM is better-suited for this purpose than the Multispectral Scanner because of its larger dynamic range. Saturation still occurs in bands 1-4, but is severe only in TM1 (0.45-0.52 micron). Snow reflectance in TM2 (0.43-0.61 micron) is typical of the visible wavelength region, where reflectance is almost insensitive to crystal size but sensitive to contamination. TM4 (0.78-0.90 micron) allows estimation of effective optical grain size and thereby spectral extension throughout the near-infrared. TM5 (1.57-1.78 microns) can discriminate clouds from snow.

Dozier, J.↗
NASA NTRS1984

Effective bandwidths for Landsat-4 and Landsat-D' multispectral scanner and thematic mapper subsystems

The spectral bands of the Multispectral Scanner and Thematic Mapper subsystems of Landsat-4 and Landsat-D' have been analyzed using a bandwidth normalization technique based on analysis of the moments of the spectral responsitivity curves. The results include the effective wavelength, the bandpass, the wavelength limits, and the normalized responsivity for each spectral channel. In addition, temperature coefficients for TM PF Channel 6 have been derived. The moments normalization method employed yields sensor parameters whose derivation is independent of source characteristics (i.e., incident solar spectral irradiance, atmospoheric transmittance, or ground reflectance). The errors expected using these parameters are lower than those expected using other normalization methods.

Palmer, J. M.↗
NASA NTRS1984

Classifying northern forests using Thematic Mapper Simulator data

Thematic Mapper Simulator data were collected over a 23,200 hectare forested area near Baxter State Park in north-central Maine. Photointerpreted ground reference information was used to drive a stratified random sampling procedure for waveband discriminant analyses and to generate training statistics and test pixel accuracies. Stepwise discriminant analyses indicated that the following bands best differentiated the thirteen level II - III cover types (in order of entry): near infrared (0.77 to 0.90 micron), blue (0.46 0.52 micron), first middle infrared (1.53 to 1.73 microns), second middle infrared (2.06 to 2.33 microsn), red (0.63 to 0.69 micron), thermal (10.32 to 12.33 microns). Classification accuracies peaked at 58 percent for thirteen level II-III land-cover classes and at 65 percent for ten level II classes.

Nelson, R. F.↗
NASA NTRS1984

Landsat thematic mapper attitude data processing

The Landsat 4 and 5 satellites carry a new, high resolution, seven band thematic mapper imaging instrument. The spacecraft also carry two types of attitude sensors: a gyroscopic internal reference unit (IRU) which senses angular rate from dc to about 2 Hz, and an AC-coupled angular displacement sensor (ADS) measuring angular deviation above 2 Hz. A description of the derivation of the crossover network used to combine and equalize the IRU and ADS data is made. Also described are the digital data processing algorithms which produce the time history of the satellites' attitude motion including the finite impulse response (FIR) implementation of G and F filters; the resampling (interpolation/decimation) and synchronization of the IRU and ADS data; and the axis rotations required as a result of the on-board sensor locations on three orthogonal axes.

Sehn, G. J.↗
NASA NTRS1984

Long-term orbit prediction for the Venus Radar Mapper Mission using an averaging method

A set of singly averaged equations of motion are presented and applied to long-term orbit prediction of an orbiting spacecraft around a slowly rotating planet, using the Venus Radar Mapper Mission as an example. The equations of motion used are valid for all eccentricities less than one. The disturbing potentials used include nonsphericity of the Venus gravity field and third-body effects due to the sun. Recursive relationships are used in the expansion and evaluation of these potentials and their respective partial derivatives. Special care is taken to optimize computational efficiency. The averaging method is compared with high precision Cowell's method using a desktop microcomputer and shows computational saving of about two orders of magnitude.

Kwok, J. H.↗
NASA NTRS1984

Venus Radar Mapper orbit accuracy analysis

Spacecraft orbital accuracies during the mapping phase of the Venus Radar Mapper Mission are the subject of this paper. The analysis presented describes the navigational strategy for the prime mission in support of mapping the planet Venus using a spacecraft deployed Synthetic Aperture Radar. Achievable orbital accuracies are shown to be limited by accuracy of interferometric data to be used. Implications of tracking system configurations and of expected degradation in data accuracy towards the end of the mission in the proximity of superior solar conjunction are examined.

Mohan, S. N.↗
NASA NTRS1984

An analytic solution for the orbital perturbations of the Venus Radar Mapper due to gravitational harmonics

Hill's variational equations are solved analytically for the orbital perturbations of a spacecraft nominally in an elliptic orbit around a non-spherical body. The rotation of the central planet about its spin-axis is not considered in the analysis. The perturbations are restricted to the planetary gravitational harmonics only. An extremely simple algorithm is derived to transform the spherical harmonic potentials to the orbital coordinate system, and the resulting accelerations are shown to be simply trigonometric functions of the true anomaly. With the principal matrix solution for the differential equations of the adjoint system given in closed form, the orthogonality of the trigonometric functions makes it possible to obtain an analytic solution for the non-homogeneous problem, at intervals of 2 pi in true anomaly. The solution for orbital perturbations can be extended over several revolutions by applying well-known results from Floquet's theory. The technique is demonstrated with results presented on the spacecraft periapsis altitude for the forthcoming Venus Radar Mapper Mission.

Vijayaraghavan, A.↗
NASA NTRS1984

Analysis of Landsat-4 Thematic Mapper data for classification of forest stands in Baldwin County, Alabama

A computer-implemented classification has been derived from Landsat-4 Thematic Mapper data acquired over Baldwin County, Alabama on January 15, 1983. One set of spectral signatures was developed from the data by utilizing a 3x3 pixel sliding window approach. An analysis of the classification produced from this technique identified forested areas. Additional information regarding only the forested areas. Additional information regarding only the forested areas was extracted by employing a pixel-by-pixel signature development program which derived spectral statistics only for pixels within the forested land covers. The spectral statistics from both approaches were integrated and the data classified. This classification was evaluated by comparing the spectral classes produced from the data against corresponding ground verification polygons. This iterative data analysis technique resulted in an overall classification accuracy of 88.4 percent correct for slash pine, young pine, loblolly pine, natural pine, and mixed hardwood-pine. An accuracy assessment matrix has been produced for the classification.

Hill, C. L.↗
NASA NTRS1984

A prospectus for Thematic Mapper research in the Earth sciences

Earth science applications of Thematic Mapper (TM) imagery are discussed. Prospective research themes are defined in a general sense in relation to the technical measurement capabilities of the TM and the various types of Earth information that can potentially be derived from multispectral TM imagery. An overview of the system developed to acquire and reduce TM data is presented. The technical capabilities of this system are presented in detail. The orbital performance of the TM sensor is described, based upon the analysis of LANDSAT 4 and 5 TM data collected to date.

Source record↗
NASA NTRS1984

Study on spectral/radiometric characteristics of the Thematic Mapper for land use applications

Progress under the LANDSAT-4 and 5 Image Data Quality Assessment program for the Thematic Mapper is described. An initial screening of LANDSAT-5 data is performed. Tools are developed to allow access to TIPS-format data. Analysis of scan direction related signal droop is resumed with detailed analysis of nighttime data. A new mathematical model is developed to describe the effect. Coherent noise of a lower frequency than previously reported is discovered and analyzed. Coincident LANDSAT-4 TM and MSS data are analyzed to improve understanding of radiometric relationships between similar wavebands in the two sensors.

Malila, W. A.↗
NASA NTRS1984

Study of spectral/radiometric characteristics of the Thematic Mapper for land use applications

Progress during the Environmental Research Institute of Michigan-ERIM's and 5 image data quality assessment program for the thematic mapper is described. Analyses of LANDSAT 5 TM radiometric characteristics were performed. Effects which had earlier been found in LANDSAT 4 TM data were found to be present in LANDSAT 5 data as well, including: (1) scan direction related signal droop; (2) scan correlated level shifts; and (3) low frequency coherent noise. Coincident LANDSAT 4 and 5 raw TM data were analyzed, and band by band relationships between the two sensors were derived. Earlier efforts which developed an information theoretic measure of multispectral information content were continued, comparing TM and MSS information content.

Malila, W. A.↗