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At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Estimating vegetation coverage in St. Joseph Bay, Florida with an airborne multispectral scanner

A four-channel multispectral scanner (MSS) carried aboard an aircraft was used to collect data along several flight paths over St. Joseph Bay, FL. Various classifications of benthic features were defined from the results of ground-truth observations. The classes were statistically correlated with MSS channel signal intensity using multivariate methods. Application of the classification measures to the MSS data set allowed computer construction of a detailed map of benthic features of the bay. Various densities of segrasses, various bottom types, and algal coverage were distinguished from water of various depths. The areal vegetation coverage of St. Joseph Bay was not significantly different from the results of a survey conducted six years previously, suggesting that seagrasses are a very stable feature of the bay bottom.

Savastano, K. J.↗
NASA NTRS1984

Agricultural applications of TM data

Multitemporal Thematic Mapper, Thematic Mapper Simulator, and detailed ground truth data were collected for a 9- by 11-km sample segment in Webster County, Iowa, in the summer of 1982. Three dates were acquired each with Thematic Mapper Simulator (June 7, June 23, and July 31) and Thematic Mapper (August 2, September 3, and October 21). The additional TM spectral bands in the middle infrared were found to substantially improve corn/soybean separability in both single date and multitemporal analyses.

Pitts, D. E.↗
NASA NTRS1983

Effective use of remote sensing products in litigation

A boiled-down version of major legal principles affecting the admissibility of data and products from remote sensing devices is presented. It is suggested that enhancements or classifications of digital data (from scanning devices or from digitized aerial photography) be proffered as evidence in a fashion similar to the manner in which maps from photogrammetric techniques are introduced as evidence. Every effort should be made to illucidate the processes by which digital data are analytically treated or manipulated. Remote sensing expert witnesses should be practiced in providing concise and clear explanations of both data and methods. Special emphasis should be placed on being prepared to provide a detailed accounting of steps taken to calibrate and verify spectral characteristics with ground truth.

Jaynes, R. A.↗
NASA NTRS1984

Investigation of SIR-B images for lithologic mapping

It is immediately apparent from the examination of almost any synthetic aperture radar (SAR) data that the radar return is primarily a function of the topographic relief. Yet radar reflectance is dependent on both surface roughness and the dielectric constant of the surface material. These two parameters can in many cases be related to lithologic units. Thus, if the first-order terrain effects due to topographic relief could (in essence) be removed from the radar image, the SAR data might well be used for lithologic discrimination. Such an approach is evaluated. Landsat Thematic Mapper data along with ground truth are used to define training cells that characterize the various lithologic units in the area. By aggregating the radar data for these cells, curves of radar reflectance versus local incidence are estimated. The curves are then used to classify the test area. The results are compared with lithologic classification based upon multi-spectral (visible and infrared) data.

Parr, J. T.↗
NASA NTRS1984

Preliminary evaluation of the airborne imaging spectrometer for vegetation analysis

The primary goal of the project was to provide ground truth and manual interpretation of data from an experimental flight of the Airborne Infrared Spectrometer (AIS) for a naturally vegetated test site. Two field visits were made; one trip to note snow conditions and temporally related vegetation states at the time of the sensor overpass, and a second trip following acquisition of prints of the AIS images for field interpretation. Unfortunately, the ability to interpret the imagery was limited by the quality of the imagery due to the experimental nature of the sensor.

Strahler, A. H.↗
NASA NTRS1985

Thermal Band Characterization of the LANDSAT-4 Thematic Mapper

The initial characterization of the Thematic Mapper (TM) thermal band is reported including gain stability, gain relation to internal calibration, corrections for channel-to-channel and scan direction differences, an approximate comparison to ground truth, and a calculation of noise equivalent temperature difference. Updated calibration information is also presented.

Lansing, J. C.↗
NASA NTRS1985

In-progress Absolute Radiometric Inflight Calibration of the LANDSAT-4 Sensors

Using selected instrumented areas at White Sands Missile Range, New Mexico as reference, radiometric calibration is to be effected on the sensors of LANDSAT 4, particularly the thematic mapper. Optical measurements made during a TM overpass are discussed. The radiances of selected large ground areas are measured in the spectral bandpasses of the TM; the total optical thickness of the atmosphere is measured in nine narrow spectral intervals. Ground truth in the form of reflectances collected for the alkalai flat region of gypsum and for the snow at White Sands is described.

Castle, K. R.↗
NASA NTRS1985

LANDSAT 4 band 6 data evaluation

Comparison of underflight data with satellite estimates of temperature revealed significant gain calibration errors. The source of the LANDSAT 5 band 6 error and its reproducibility is not yet adequately defined. The error can be accounted for using underflight or ground truth data. When underflight data are used to correct the satellite data, the residual error for the scene studied was 1.3K when the predicted temperatures were compared to measured surface temperature.

Source record↗
NASA NTRS1985

Nasa's Land Remote Sensing Plans for the 1980's

Research since the launch of LANDSAT-1 has been primarily directed to the development of analysis techniques and to the conduct of applications studies designed to address resource information needs in the United States and in many other countries. The current measurement capabilities represented by MSS, TM, and SIR-A and B, coupled with the present level of remote sensing understanding and the state of knowledge in the discipline earth sciences, form the foundation for NASA's Land Processes Program. Science issues to be systematically addressed include: energy balance, hydrologic cycle, biogeochemical cycles, biological productivity, rock cycle, landscape development, geological and botanical associations, and land surface inventory, monitoring, and modeling. A global perspective is required for using remote sensing technology for problem solving or applications context. A successful model for this kind of activity involves joint research with a user entity where the user provides a test site and ground truth and NASA provides the remote sensing techniques to be tested.

Higg, H. C.↗
NASA NTRS1985

Analysis of the NASA/MSFC airborne Doppler lidar results from San Gorgonio Pass, California

The NASA/MSFC Airborne Doppler Lidar System was flown in July 1981 aboard the NASA/Ames Convair 990 on the east side of San Gorgonio Pass California, near Palm Springs, to measure and investigate the accelerated atmospheric wind field discharging from the pass. At this region, the maritime layer from the west coast accelerates through the pass and spreads out over the valley floor on the east side of the pass. The experiment was selected in order to study accelerated flow in and at the exit of the canyon. Ground truth wind data taken concurrently with the flight data were available from approximately 12 meteorological towers and 3 tala kites for limited comparison purposes. The experiment provided the first spatial data for ensemble averaging of spatial correlations to compute lateral and longitudinal length scales in the lateral and longitudinal directions for both components, and information on atmospheric flow in this region of interest from wind energy resource considerations.

Cliff, W. C.↗
NASA NTRS1984

Early season spring small grains proportion estimation

An accurate, automated method for estimating early season spring small grains from Landsat MSS data is discussed. The method is summarized and the results of its application to 100 sample segment-years of data from the US Northern Great Plains in 1976, 1977, 1978, and 1979 are summarized. The results show that this estimator provides accurate estimates earlier in the growing season than previous methods. Ground truth is required only in the estimator development, and data storage, transmission, preprocessing, and processing requirements are minimal.

Phinney, D. E.↗
NASA NTRS1984

Assessment of Landsat multispectral scanner spectral indexes for monitoring arid rangeland

Correlations between spectral indices and vegetation parameters in south-central New Mexico were used to determine the utility of Landsat Multispectral Scanner (MSS) spectral indices in arid rangeland monitoring. In addition, spectral index change for 1976-1980 was calculated from retrospective MSS data and compared with qualitative ground truth in order to evaluate vegetation change detection by means of spectral indices. Brightness index change consistently differentiated between cover increase and decrease, but index change appears to have been offset from true cover change; this may at least partly be attributed to the failure of the methods used to standardize MSS scenes for differences in sensor response. Green vegetation indices, by contrast to brightness indices, failed to consistently differentiate between cover increase and decrease.

Musick, H. B.↗
NASA NTRS1984

Intercomparison of planetary-scale diagnostics derived from separate satellite and radiosonde time-mean temperature fields

The planetary-scale components of the extratropical Northern Hemisphere troposphere-stratosphere 1973-74 winter circulation are diagnosed using separate time-mean temperature fields based on radiosonde and satellite observations. Meridional cross-sections of zonal wind together with, for zonal wavenumbers 1, 2 and 3, the streamfunction amplitude, phase and Eliassen-Palm flux are displayed, with the relative accuracy of the satellite-derived diagnostics assessed through comparison with the 'ground-truth' radiosonde information. The satellite and radiosonde diagnostics compare most favourably in terms of zonal wind speed and shear, direction of wave propagation and meridional wave structure - all of which are closely related to the differential properties of the atmospheric temperature field. The intensity of the satellite-derived patterns of tropospheric wave propagation is underestimated due to the effects of spatial smoothing and residual cloud contamination present in the satellite radiance measurements.

Miles, T.↗
NASA NTRS1983

Development of visible/infrared/microwave agriculture classification and biomass estimation algorithms

This paper describes the results of a study to determine if crop acreage and biomass estimates could be improved by using visible IR and microwave data. The objectives were to (1) develop and test agricultural crop classification models using two or more spectral regions (visible through microwave), and (2) estimate biomass by including microwave with visible and infrared data. Aircraft multispectral data collected during the study included visible and infrared data (multiband data from 0.5 m - 12 m), and active microwave data K band (2 cm), C band (6 cm), L band (20 cm), and P band (75 cm) HH and HV polarizations. Ground truth data from each field consisted of soil moisture and biomass measurements. Results indicated that C, L, and P band active microwave data combined with visible and infrared data improved crop discrimination and biomass estimates compared to results using only visible and infrared data. The active microwave frequencies were sensitive to different biomass levels; K and C being sensitive to differences at low biomass levels, while P band was sensitive to differences at high biomass levels.

Rosenthal, W. D.↗
NASA NTRS1984

Measuring spectra of arid lands

The principles, instrumentation and data acquisition and interpretation techniques employed in multispectral remote sensing for geological applications are surveyed. Sensing is based on exact measurements of electromagnetic radiation interacting with atoms and molecules in the sensed scene. Absorbed radiation can be used to identify elements in the near-IR bands and emitted or reflected energy can be sensed in the mid- and far-IR. Sunlight normally serves as the exciting source. Wavelength absorptance and emittance characteristics are distinct for the various elements and molecules such as transition metal ions, water, carbonates, etc. The bands for identifying different materials are determined in the laboratory, followed by ground truth field tests. Several hand-held radiometers and spectrometers have been developed for the field trials. Each instrument usually has a limited detection range and serves for developing a data base for subtle distinctions among contiguous minerals with similar radiometric signatures. The data serve for calibrating first airborne and then satellite sensors, e.g., the Landsat MSS and Thematic Mapper. Instruments are also being tested using the Orbiter as the test platform.

Kahle, A. B.↗
NASA NTRS1984

Comparison of ozone data derived from SBUV and SAGE with emphasis on longitudinal variations

Stratospheric ozone observations performed by the SBAV and SAGE satellite instruments in March and April 1979 are analyzed and compared to other data, where available; in the absence of ground-truth data the experimental uncertainties are modeled by intercomparison of the measurements. The signal-to-noise ratios for the detectability of longitudinal variation in ozone are estimated for both SBUV and SAGE instruments. The analysis of longitudinal variation data reveals significant differences in amplitudes obtained in individual events in which rapid amplitude changes with height were present. Finally, a systematic overestimation of ozone by 20 percent by the SAGE instrument and underestimation by SBUV by about 15 percent at 50-70 latitudes at 10 mb is noted.

Cunnold, D.↗
NASA NTRS1985

Mars - Dual-polarization radar observations with extended coverage

Arecibo Observatory radar observations of Mars at 13 cm wavelength have yielded accurate measurements of the full backscatter spectrum in two orthogonal polarizations, and constitute the first global view of the small scale surface roughness distribution on Mars. Areas of maximum depolarization correlate well with the volcanic regions Tharsis and Elysium. Comparisons between the moon and Mars using radar data, ground truth, and simple scattering models, suggest that Mars possesses a relatively high average coverage by decimeter-scale rocks. Attention is also given to quasi-specular scattering results, of which the most unusual were obtained over the Olympus Mons aureole region.

Harmon, J. K.↗