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At least 19 recordsLinked to original sources
USGS1993

Twenty years of Landsat data accessible through the national satellite land remote sensing data archive

The EROS Data Center has managed to National Satellite Land Remote Sensing Data Archive's (NSLRSDA) Landsat data since 1972. The NSLRSDA includes Landsat MSS data from 1972 through 1991 and T M data from 1982 through 1993. In response to many requests from multi-disciplined users for an enhanced insight into the availability and volume of Landsat data over specific worldwide land areas, numerous world plots and corresponding statical overviews have been prepared. These presentations include information related to image quality, cloud cover, various types of data overage (i.e. regions, countries, path, rows), acquisition station coverage areas, various archive media formats (i.e. wide band video tapes, computer compatible tapes, high density tapes, etc.) and acquisition time periods (i.e. years, seasons). Plans are to publish this information in a paper sample booklet at the Pecora 12 Symposium, in a USGS circular and on a Landsat CD-ROM; the data will be also be incorporated into GLIS.

Pecora 12 Symposium↗
USGS1993

Identification of requirements and sources for global digital topographic data

Many of the physical processes being studied by global change researchers are affects by land surface topography and consequently topographic data are an important requirement for these investigations. Remotely sensed data, especially those that will be collected by the instruments of the Earth Observing System, require significant correction to remove topographic effects. Although some requirements are met by existing topographic data, there are serious data shortages that will affect global change science. The interdisciplinary and multi temporal natural of global change research requires that remotely sensed data be processed using a consistent, highly accurate global topographic database so that information extracted from these data for different areas and times can be compared quantitively. Cartographic and remote sensing sources for the generation of new topographic data exist or are planned and will be helpful for fulfilling these requirements. More consistent use of accuracy statement terminology by data users and producers is necessary to better compare the requirements with existing or future data sets.

Pecora 12 Symposium↗
USGS1993

Identifying high production, low production and degraded rangelands in Senegal with normalized difference vegetation index data

Seasonal herbaceous vegetation production on Senegal's native rangelands exhibits high spatial and temporal variability. This variability can be monitored using normalized difference vegetation index (NDVI) data computed from 1-km resolution Advanced Very High Resolution Radiometer (AVHRR) image data. Although annual fluctuations in rainfall account for some of the variability, numerous long-term production patterns are evident in the AVHRR time-series data. Different n productivity reflect variations in the region's climate, topography, soils, and land use. Areas of overgrazing and intensive cultivation have caused long-term soil and vegetation degradation. Rangelands of high and low productivity, and degraded rangelands were identified using NDVI. Time-series image data from 1987 though 1992 were used to map relative rangeland productivity. The results were compared to detailed resource maps on soils, vegetation and land use. Much of the variation in rangeland productivity correlated well to the known distribution of resources. The study developed an approach that identified a number of areas of degraded soils and low vegetation production.

Pecora 12 Symposium↗
USGS1993

Compositing multitemporal remote sensing data sets

To eliminate cloud and atmosphere-affected pixels, the compositing of multi temporal remote sensing data sets is done by selecting the maximum vale of the normalized different vegetation index (NDVI) within a compositing period. The NDVI classifier, however, is strongly affected by surface type and anisotropic properties, sensor viewing geometries, and atmospheric conditions. Consequently, the composited, multi temporal, remote sensing data contain substantial noise from these external conditions. Consequently, the composited, multi temporal, remote sensing data contain substantial noise from these external effects. To improve the accuracy of compositing products, two key approaches can be taken: one is to refine the compositing classifier (NDVI) and the other is to improve existing compositing algorithms. In this project, an alternative classifier was developed and an alternative pixel selection criterion was proposed for compositing. The new classifier and the alternative compositing algorithm were applied to an advanced very high resolution radiometer data set of different biome types in the United States. The results were compared with the maximum value compositing and the best index slope extraction algorithms. The new approaches greatly reduced the high frequency noises related to the external factors and repainted more reliable data. The results suggest that the geometric-optical canopy properties of specific biomes may be needed in compositing. Limitations of the new approaches include the dependency of pixel selection on the length of the composite period and data discontinuity.

Pecora 12 Symposium↗
USGS1993

Processing techniques for global land 1-km AVHRR data

The U.S. Geological Survey's (USGS) Earth Resources Observation Systems (EROS) Data Center (EDC) in cooperation with several international science organizations has developed techniques for processing daily Advanced Very High Resolution Radiometer (AVHRR) 1-km data of the entire global land surface. These techniques include orbital stitching, geometric rectification, radiometric calibration, and atmospheric correction. An orbital stitching algorithm was developed to combine consecutive observations acquired along an orbit by ground receiving stations into contiguous half-orbital segments. The geometric rectification process uses an AVHRR satellite model that contains modules for forward mapping, forward terrain correction, and inverse mapping with terrain correction. The correction is accomplished by using the hydrologic features coastlines and lakes from the Digital Chart of the World. These features are rasterized into the satellite projection and are matched to the AVHRR imagery using binary edge correlation techniques. The resulting coefficients are related to six attitude correction parameters: roll, roll rate, pitch, pitch rate, yaw, and altitude. The image can then be precision corrected to a variety of map projections and user-selected image frames. Because the AVHRR lacks onboard calibration for the optical wavelengths, a series of time-variant calibration coefficients derived from vicarious calibration methods and are used to model the degradation profile of the instruments. Reducing atmospheric effects on AVHRR data is important. A method has been develop that will remove the effects of molecular scattering and absorption from clear sky observations, using climatological measurements of ozone. Other methods to remove the effects of water vapor and aerosols are being investigated.

Pecora 12 Symposium↗
USGS1993

Raster profile development for the spatial data transfer standard

The Spatial Data Transfer Standard (SDTS), recently approved as Federal Information Processing Standard (FIPS) Publication 173, is designed to transfer various types of spatial data. Implementing all of the standard's options at one time is impractical. Profiles, or limited subsets of the SDTS, are the mechanisms by which the standards will be implemented. The development of a raster profile is being coordinated by the U.S. Geological Survey's (USGS) SDTS Task Force. This raster profile is intended to accommodate digital georeferenced image data and regularly spaces, georeferenced gridded data. The USGS's digital elevation models (DEMs) and digital orthophoto quadrangles (DOQs), National Oceanic and Atmospheric Administration's (NOAA) advanced very huh resolution radiometer (AVHRR) and Landsat data, and National Aeronautics and Space Administration's (NASA) Earth observing system (EOS) data are among the candidate data sets for this profile. Other raster profiles, designed to support nongeoreferenced and other types of "raw" sensor data will be consider in the future. As with the Topological Vector Profile (TVP) for the SDTS, development of the raster profile includes designing a prototype profile, testing the prototype profile using sample data sets, and finally, requesting and receiving FIPS approval.

Pecora 12 Symposium↗
USGS1993

Availability of Earth observations data from the U.S. Geological Survey's EROS data center

For decades federal and state agencies have been collecting regional, continental, and global Earth observations data acquired by satellites, aircraft, and other information-gathering systems. These data include photographic and digital remotely sensed images of the Earth's surface, as well as earth science, cartographic, and geographic data. Since 1973, the U.S. Geological Survey's Earth Resources Observation Systems (EROS) Data Center (EDC) in Sioux Falls, South Dakota, has been a data management, production, dissemination, and research center for these data. Currently, the Data Center holds over 10 million satellite images and aerial photographs, in photographic and digital formats. Users are able to place inquiries and orders for these holdings via a nationwide computer network. In addition to cataloging the data stored in its archives, the Data Center provides users with rapid access to information on many data collections held by other facilities.

Pecora 12 Symposium↗
USGS1993

A temporal comparison of forest cover using digital earth science data and visualization techniques

Increased demands on forest resources and the recognition of old-growth forests as critical habitats and purifiers of the atmosphere have stimulated attention to forest harvest practices in the United States and worldwide. Visualization technology provides a means by which a history of forestry activities may be documented and presented to the public and decisionmakers. In this project, landsat multispectral scanner and thematic mapper images, acquired July 7, 1981, and July 8, 1991, respectively, were georeferenced, resampled, enhanced, and draped over U.S. Geological Survey 30-meter digital elevation models. These data then were used to create perspective views of portions of Mt. Hood Forest, Oregon. The "fly-by" animation (produced by rapidly displaying a sequence of these perspective views) conveys the forest cover change resulting from forest harvest activities over the 10-year period. This project shows the value of combining satellite data with base cartographic data and earth science information for use in public education and decision-making processes.

Pecora 12 Symposium↗
USGS1993

An innovative partnership for national environmental assessment

Four federal environmental programs: EMAP (USEPA), GAP (USFWS), C-CAP (NOAA), NAWQA (USGS) have formed a partnership with EROS Data Center (USGS) to facilitate the development of baseline land characteristics information for the conterminous U.S. Each of the respective programs brings to the group unique experience and expertise. Despite emphasis on different environmental issues, together we have identified common requirements for source satellite data, preprocessing, spectral clustering, ancillary data, data management and distribution. We are also developing a research agenda to support this initiative and future efforts of this partnership. The short-term goal of out effort is the joint acquisition and preprocessing of recent Landsat TM images for the conterminous U.S. To date, images have been identified for acquisition, and preliminary plans have been made for preprocessing. The long-term goal for this group is collaborative research and development of a flexible and functional land characteristics database for use by our programs and others. This partnership demonstrates that national environmental programs within multiple government agencies can work effectively together to achieve common goals and reduce overall cost.

Pecora 12 Symposium↗
USGS1993

An evaluation of atmospheric corrections to advanced very high resolution radiometer data

A data set compiled to analyze vegetation indices is used to evaluate the effect of atmospheric correction to AVHRR measurement in the solar spectrum. Such corrections include cloud screening and "clear sky" corrections. We used the "clouds from AVHRR" (CLAVR) method for cloud detection and evaluated its performance over vegetated targets. Clear sky corrections, designed to reduce the effects of molecular scattering and absorption due to ozone, water vapor, carbon dioxide, and molecular oxygen, were applied to data values determine to be cloud free. Generally, it was found that the screening and correction of the AVHRR data did not affect the maximum NDVI compositing process adversely, while at the same time improving estimates of the land-surface radiances over a compositing period.

Pecora 12 Symposium↗
USGS1993

Integration of environmental simulation models with satellite remote sensing and geographic information systems technologies: case studies

Environmental modelers are testing and evaluating a prototype land cover characteristics database for the conterminous United States developed by the EROS Data Center of the U.S. Geological Survey and the University of Nebraska Center for Advanced Land Management Information Technologies. This database was developed from multi temporal, 1-kilometer advanced very high resolution radiometer (AVHRR) data for 1990 and various ancillary data sets such as elevation, ecological regions, and selected climatic normals. Several case studies using this database were analyzed to illustrate the integration of satellite remote sensing and geographic information systems technologies with land-atmosphere interactions models at a variety of spatial and temporal scales. The case studies are representative of contemporary environmental simulation modeling at local to regional levels in global change research, land and water resource management, and environmental simulation modeling at local to regional levels in global change research, land and water resource management and environmental risk assessment. The case studies feature land surface parameterizations for atmospheric mesoscale and global climate models; biogenic-hydrocarbons emissions models; distributed parameter watershed and other hydrological models; and various ecological models such as ecosystem, dynamics, biogeochemical cycles, ecotone variability, and equilibrium vegetation models. The case studies demonstrate the important of multi temporal AVHRR data to develop to develop and maintain a flexible, near-realtime land cover characteristics database. Moreover, such a flexible database is needed to derive various vegetation classification schemes, to aggregate data for nested models, to develop remote sensing algorithms, and to provide data on dynamic landscape characteristics. The case studies illustrate how such a database supports research on spatial heterogeneity, land use, sensitivity analysis, and scaling issues involving regional extrapolations and parameterizations of dynamic land processes within simulation models.

Pecora 12 Symposium↗
USGS1993

Development of a graphical user interface for the global land information system (GLIS)

The process of developing a Motif Graphical User Interface for the Global Land Information System (GLIS) involved incorporating user requirements, in-house visual and functional design requirements, and Open Software Foundation (OSF) Motif style guide standards. Motif user interface windows have been developed using the software to support Motif window functions war written using the C programming language. The GLIS architecture was modified to support multiple servers and remote handlers running the X Window System by forming a network of servers and handlers connected by TCP/IP communications. In April 1993, prior to release the GLIS graphical user interface and system architecture modifications were test by developers and users located at the EROS Data Center and 11 beta test sites across the country.

Pecora 12 Symposium↗
USGS1993

"Relative CIR": an image enhancement and visualization technique

Many techniques exist to spectrally and spatially enhance digital multispectral scanner data. One technique enhances an image while keeping the colors as they would appear in a color-infrared (CIR) image. This "relative CIR" technique generates an image that is both spectrally and spatially enhanced, while displaying a maximum range of colors. The technique enables an interpreter to visualize either spectral or land cover classes by their relative CIR characteristics. A relative CIR image is generated by developed spectral statistics for each class in the classifications and then, using a nonparametric approach for spectral enhancement, the means of the classes for each band are ranked. A 3 by 3 pixel smoothing filter is applied to the classification for spatial enhancement and the classes are mapped to the representative rank for each band. Practical applications of the technique include displaying an image classification product as a CIR image that was not derived directly from a spectral image, visualizing how a land cover classification would look as a CIR image, and displaying a spectral classification or intermediate product that will be used to label spectral classes.

Pecora 12 Symposium↗
USGS1993

The U.S. Geological Survey side-looking airborne radar database: an aid to the interpretation of space images

The U.S. Geological Survey (USGS) has a database of side-looking airborne radar (SLAR) images of a significant part of the continental United States. These images provide a regional view of terrains and should be an aid to better understanding image data of satellite synthetic aperture radar (SAR) and other systems. The USGS has been systematically collecting SLAR since 1980, initially in analog form, then in both analog and digital format since 1984.

Pecora 12 Symposium↗
USGS1993

CD-ROM technology at the EROS data center

The vast amount of digital spatial data often required by a single user has created a demand for media alternatives to 1/2" magnetic tape. One such medium that has been recently adopted at the U.S. Geological Survey's EROS Data Center is the compact disc (CD). CD's are a versatile, dynamic, and low-cost method for providing a variety of data on a single media device and are compatible with various computer platforms. CD drives are available for personal computers, UNIX workstations, and mainframe systems, either directly connected, or through a network. This medium furnishes a quick method of reproducing and distributing large amounts of data on a single CD. Several data sets are already available on CD's, including collections of historical Landsat multispectral scanner data and biweekly composites of Advanced Very High Resolution Radiometer data for the conterminous United States. The EROS Data Center intends to provide even more data sets on CD's. Plans include specific data sets on a customized disc to fulfill individual requests, and mass production of unique data sets for large-scale distribution. Requests for a single compact disc-read only memory (CD-ROM) containing a large volume of data either for archiving or for one-time distribution can be addressed with a CD-write once (CD-WO) unit. Mass production and large-scale distribution will require CD-ROM replication and mastering.

Pecora 12 Symposium↗
USGS1993

The proposed EROSpace institute, a national center operated by space grant universities

The "EROSpace Institute" is a proposed visiting scientist program in associated with the U.S. Geological Survey's EROS Data Center (EDC). The Institute would be operated by a consortium of universities, possible drawn from NASA's Space Grant College and Fellowship Program consortia and the group of 17 capability-enhancement consortia, or perhaps from consortia though out the nation with a topical interest in remote sensing. The National Center for Atmospheric Research or the Goddard Institute for Space Studies provide models for the structure of such an institute. The objectives of the Institute are to provide ready access to the body of data housed at the EDC and to increase the cadre of knowledgeable and trained scientists able to deal with the increasing volume of remote sensing data to become available from the Earth Observing System. The Institute would have a staff of about 100 scientists at any one time, about half permanent staff, and half visiting scientists. The latter would include graduate and undergraduate students, as well as faculty on temporary visits, summer fellowships, or sabbatical leaves. The Institute would provide office and computing facilities, as well as Internet linkages to the home institutions so that scientists could continue to participate in the program from their home base.

Pecora 12 Symposium↗
USGS1993

Global land information system (GLIS) access to worldwide Landsat data

The Landsat Technical Working Group (LTWG) and the Landsat Ground Station Operations Working Group (LGSOWG) have encouraged Landsat receiving stations around the world to share information about their data holdings through the exchange of metadata records. Receiving stations forward their metadata records to the U.S. Geological Survey's EROS Data Center (EDC) on a quarterly basis. The EDC maintains the records for each station, coordinates changes to the database, and provides metadata to the stations as requested. The result is a comprehensive international database listing most of the world's Landsat data acquisitions This exchange of information began in the early 1980's with the inclusion in the EDC database os scenes acquired by a receiving station in Italy. Through the years other stations have agreed to participate; currently ten of the seventeen stations actively share their metadata records. Coverage maps have been generated to depict the status of the database. The Worldwide Landsat database is also available though the Global Land Information System (GLIS).

Pecora 12 Symposium↗
USGS1993

A practical implementation for a data dictionary in an environment of diverse data sets

The need for a data dictionary database at the U.S. Geological Survey's EROS Data Center (EDC) was reinforced with the Earth Observing System Data and Information System (EOSDIS) requirement for consistent field definitions of data sets residing at more than one archive center. The EDC requirement addresses the existence of multiple sets with identical field definitions using various naming conventions. The EDC is developing a data dictionary database to accomplish the following foals: to standardize field names for ease in software development; to facilitate querying and updating of the date; and to generate ad hoc reports. The structure of the EDC electronic data dictionary database supports different metadata systems as well as many different data sets. A series of reports is used to keep consistency among data sets and various metadata systems.

Pecora 12 Symposium↗