Satellite Image Map of Antarctica
Using Advanced Very High Resolution Radiometer (AVHRR) Images Click on thumbnail images below to browse full resolution mosaic.
A major advantage of remotely sensed satellite images is the regional/synoptic view of the data. The regional perspective view is enhanced further by digitally mosaicking different images collected by the same satellite to cover an even larger regional area. Another advantage is the multitemporal aspect of satellite images, which can be used to monitor changes on the Earth's surface or update an existing data set. In this particular case an existing digital AVHRR satellite image mosaic was updated with newer and better images to replace cloud covered areas, and digital image processing techniques were used to improve the presentation of the data. The United States Geological Survey's (USGS) Mini Image Processing System (MIPS) was used to apply the geometric, radiometric, and spatial filtering required to update and improve the existing digital mosaic, as well as the merging of AVHRR and topographic images. The digital image map results shown here were published in hardcopy format as USGS Miscellaneous Investigation Series Map I-2560. The hardcopy image map scale is 1:5,000,000 with selected geographic names and contours printed on the image base. The image map was prepared by the USGS with joint support from the National Science Foundation Interagency Agreement OPP-9114787. The following text, with slight modifications, was extracted from the published hardcopy version.
The satellite images used in the mosaic were acquired by the Advanced Very High Resolution Radiometer (AVHRR) sensors on the National Oceanic and Atmospheric Administration (NOAA) satellites; the images used in the mosaic were collected during the period 1980 to 1994. Although the AVHRR scans a 2400 km-wide swath and can image nearly half of the continent of Antarctica on a single orbit, 63 sections of 38 scenes were needed to compile the nearly cloud-free digital mosaic.
The digital image mosaic used as input was previously mosaicked, controlled, and geometrically corrected into a Polar Stereographic projection by the National Remote Sensing Center, United Kingdom. Details of the processing they used to generate the original mosaic can be found in the International Journal of Remote Sensing (1989, v. 10, nos. 4 and 5, p. 669-674). The USGS evaluated the geometric accuracy of the mosaic and estimated a root-mean-square error of 2.5 km. The digital image processing that created this modified image base was done at the USGS Flagstaff Field Center, Flagstaff, Arizona. Replacement images were geometrically corrected to the first image base, digitally inserted into the mosaic, and radiometrically/tone matched to blend with the surrounding images. When the entire mosaic was completed band 1 (visible, 0.58-0.68 micrometers) and band 2 (near-infrared, 0.725-1.100 micrometers) were averaged, and the entire digital mosaic was enhanced using a 91 by 91 pixel spatial filter; these results were then contrast stretched.
Hardcopy Map:
The published hardcopy version, USGS map I-2560 authored by:
Jane G. Ferrigno, Jerry L. Mullins, JoAnne Stapleton, Pat S. Chavez, Jr., Miguel G. Velasco, Richard S. Williams, Jr., George F. Delinski, Jr., and D'Ann Lear
is for sale by the U.S. Geological Survey Information Services, Box 25286, Federal Center, Denver, CO 80225.
The black and white image shown above is equivalent to the image map base used in the published hardcopy format. To show the multispectral (color) information contained in the data, a color composite was made using the processed and enhanced spectral bands 1, 2, and their sum; they were used as blue, green, and red, respectively. In the visible and near-infrared spectral regions snow and ice are relatively flat, however, enough color differences exist that variations among snow, ice, blue ice, and exposed rock can be seen.
The Antarctica digital elevation model (DEM) was acquired from a USGS EROS Data Center world wide web page, and are part of the global GTOPO30 data available from the EDC. The DEM data, like the AVHRR mosaic, are in a polar stereographic projection with 1 km resolution and only simple scaling and translation were used to geometrically register the two images. The documentation supplied with the DEMs state that they were generated from contour and coastline data made available by the Antarctic Digital Database (ADD), which was produced under the guidance of the Scientific Committee on Antarctic Research (SCAR). These data were then used as input to the Australian National University Digital Elevation Model (ANUDEM) computer program developed by Michael Hutchinson. The absolute accuracy of the DEM grid has not been measured or calculated. The original data and maps used to compile the final DEM had better spatial resolution and height accuracy along coastal areas; this data quality difference is visible in both the compressed DEM and shaded relief images shown on the following page:
For more information about this project, contact:
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