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Bryant, N.

Publications and source records attributed to Bryant, N..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Obtaining Accurate Change Detection Results from High-Resolution Satellite Sensors

Multi-date acquisitions of high-resolution imaging satellites (e.g. GeoEye and WorldView), can display local changes of current economic interest. However, their large data volume precludes effective manual analysis, requiring image co-registration followed by image-to-image change detection, preferably with minimal analyst attention. We have recently developed an automatic change detection procedure that minimizes false-positives. The processing steps include: (a) Conversion of both the pre- and post- images to reflectance values (this step is of critical importance when different sensors are involved); reflectance values can be either top-of-atmosphere units or have full aerosol optical depth calibration applied using bi-directional reflectance knowledge. (b) Panchromatic band image-to-image co-registration, using an orthorectified base reference image (e.g. Digital Orthophoto Quadrangle) and a digital elevation model; this step can be improved if a stereo-pair of images have been acquired on one of the image dates. (c) Pan-sharpening of the multispectral data to assure recognition of change objects at the highest resolution. (d) Characterization of multispectral data in the post-image ( i.e. the background) using unsupervised cluster analysis. (e) Band ratio selection in the post-image to separate surface materials of interest from the background. (f) Preparing a pre-to-post change image. (g) Identifying locations where change has occurred involving materials of interest.

multispectral↗
NASA NTRS2005

Satellite Infrared Radiation Measurements Prior to the Major Earthquakes

This work describes our search for a relationship between tectonic stresses and increases in mid-infrared (IR) flux as part of a possible ensemble of electromagnetic (EM) phenomena that may be related to earthquake activity. We present and &scuss observed variations in thermal transients and radiation fields prior to the earthquakes of Jan 22, 2003 Colima (M6.7) Mexico, Sept. 28 .2004 near Parkfield (M6.0) in California and Northern Sumatra (M8.5) Dec. 26,2004. Previous analysis of earthquake events has indicated the presence of an IR anomaly, where temperatures increased or did not return to its usual nighttime value. Our procedures analyze nighttime satellite data that records the general condtion of the ground after sunset. We have found from the MODIS instrument data that five days before the Colima earthquake the IR land surface nighttime temperature rose up to +4 degrees C in a 100 km radius around the epicenter. The IR transient field recorded by MODIS in the vicinity of Parkfield, also with a cloud free environment, was around +1 degree C and is significantly smaller than the IR anomaly around the Colima epicenter. Ground surface temperatures near the Parkfield epicenter four days prior to the earthquake show steady increase. However, on the night preceding the quake, a significant drop in relative humidity was indicated, process similar to those register prior to the Colima event. Recent analyses of continuous ongoing long- wavelength Earth radiation (OLR) indicate significant and anomalous variability prior to some earthquakes. The cause of these anomalies is not well understood but could be the result of a triggering by an interaction between the lithosphere-hydrosphere and atmospheric related to changes in the near surface electrical field and/or gas composition prior to the earthquake. The OLR anomaly usually covers large areas surrounding the main epicenter. We have found strong anomalies signal (two sigma) along the epicentral area signals on Dec 21, five days prior to the Northern Sumatra quake compared to the reference field for December 2001-2004 periods. Our recent results support the hypothesis of a possible relationship between a thermodynamic processes produced by increasing tectonic stress in the Earth's crust and a subsequent electro-chemical interaction between this crust and the atmosphere/ionosphere.

Ouzounov, Dimitar↗
NASA NTRS1996

Object-Oriented Geographical Database Model

Terbase is an Object-Oriented database system under development at the Jet Propulsion Laboratory (JPL). Terbase is designed for flexibility, reusability, maintenace ease, multi-user collaboration and independence, and efficiency. This paper details the design and development of Terbase as a geographic data server...

Terbase Object-Oriented database system Tactical M↗
NASA NTRS1982

Geographic science

The use of multispectral imaging systems in land use, geomorphological, and cartographic applications is examined. Spatial, spectral, and geometric resolution requirements for photo interpretation and multispectral pattern recognition are discussed. The potential contributions of these systems in specific experiments is also included.

Bryant, N.↗
NASA NTRS1982

Geographic science team

The rational for using remote sensing in land use/land cover, geomorphology, and cartography applications is stated as well as potential uses in each of these areas. The next step to be perfected is indicated. Spatial and spectral resolution requirements for photointerpretations and/or multispectral pattern recognition of geomorphic elements and of cultural surface cover are listed. Requirements for photographic/analog or digital photogrammetry from spaceborne multispectral linear array sensors are included. A prioritized summary of data gaps in the geographic sciences is included.

Bryant, N.↗
NASA NTRS1981

Lake classification in Vermont

In order to comply with the Federal Clean Water Act and, in so doing, develop a procedure to periodically update the classification, the State of Vermont evaluated the ability of LANDSAT to detect general water quality and specific water quality parameters in Vermont lakes. Unsupervised and supervised classifications as well as regression analyses were used to examine LANDSAT data from Lake Champlain and from four small nearby lakes. Unsupervised and supervised classifications were found to be of somewhat limited value. Regression analyses revealed a good correlation between depth-integrated total phosphorus concentrations and LANDSAT band 4 data (r2= 0.92) and between Secchi disk transparencies and LANDSAT band 4 data (r2 - 0.85). No correlation was found between depth-integrated chlorophyll-a samples and LANDSAT data. Vermont is expanding this LANDSAT evaluation to include the remaining lakes in the state greater than twenty acres and steps are being taken to incorporate LANDSAT into the state's ongoing water quality monitoring programs.

Garrison, V.↗
NASA NTRS1978

Seasat land experiments

An overview of the Seasat land experiments is presented. The potential roles for active microwave imaging systems on board satellites were reviewed with particular emphasis on the Seasat Synthetic Aperture Radar (SAR). Recommendations were made concerning the type of experiments that could most profitably be conducted over land with the Seasat SAR system capabilities available.

Estes, J. E.↗