Jun 17, 2004 | ||||||||
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URL to backscatter image: http://blacks.jpl.nasa.gov/PRECISION/ts1610.jpg | ||||||||
The
standard AIRSAR data files are included on the CD-ROM/DVD along with
browse GIF image files. Please
note that due to large file sizes, CD-ROM’s may be too small to hold
all the data, and the data might be spread across multiple discs.
For more information about what these files are and the format,
please visit the http://airsar.jpl.nasa.gov
web page. |
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This data was acquired in a mixed bandwidth mode. However, we have processed the imagery so that the data will be co-registered. The resolution and swath are dependent on the bandwidth, so the smaller bandwidth data has a worse resolution than the higher bandwidth data, and we have not processed some of the swath from the smaller bandwidth data. | ||||||||
Tie-pointing information 3 Ground control points (GCPs) for the ts1610 product were obtained from the SRTM DEM 30 m postings scale maps, which have approx 5m contour intervals. We made our best effort to find GCP's that span the cross-track dimension of the imagery. The offset between the datum of the maps and the WGS84 ellipsoid for this product was 0.00000 meters. This offset was applied when calculating the absolute height of the AIRSAR DEM. Therefore, the height values of the AIRSAR DEM will differ from the height values of the topographic maps by this amount. During tie-pointing, we applied the offset between the datum of the maps and the WGS84 datum that AIRSAR uses, and compared these heights with the heights read off the AIRSAR DEM. We then calculated the height offset/tilt that produces a DEM in best agreement with the map values. At this stage, the geo-location of the GCP's is not considered. The c-band height offset applied was 70.2923 m, and the phase correction corresponding to the tilt correction was -2.76197 cycles.The l-band height offset applied was 62.6895 m, and the phase correction corresponding to the tilt correction was -0.384750 cycles. The mean and standard deviation of the height difference between the map values and the image values is 3.07121 m and stdev =3.39971 m at c-band.The mean and standard deviation of the height difference between the map values and the image values is 2.72656 m and stdev =4.20603 m at l-band. You may want to apply additional GCPs as part of your analysis. |
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Additional Comments | ||||||||
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steep terrain results in more phase unwrapping errors than usual. | ||||||||
If you have any questions, please contact Bruce Chapman at: Tel: 818-354-3603 Fax: 818-393-5285 E-mail: bruce.chapman@jpl.nasa.gov |