Landsat Missions
The Level 1 Scan Line Corrector (SLC)-off product includes a small (2-pixel) interpolation along the scan line boundary during level 1 processing. However, users may also select an alternate number of pixels to be interpolated across the scan line boundary.
Selection of the maximum interpolation value (=15 pixels) provides a fully populated image in which all missing pixels have been filled with Descending Node (DN) values interpolated from neighboring scan lines (Figure 1). There will be increasing degradation of image quality within alternate scan lines toward the edge of the scene because these are interpolated rather than real data values (Figure 1). Interpolated data values within the interpolated region will not be correlative with actual features. However, the unaffected scan lines will be of similar quality to all previous Landsat 7 (SLC-on) data (Figure 2).
Figure 1. L1G product with 15-pixel interpolation, illustrating the fully populated image data along the scene edge. Note the disruption of linear features along alternating scan lines.
Figure 2. L1G interpolated product, showing nominal image data at the scene center.
Note that all replacement data values are derived from within the current SLC-off image. An SLC-off interpolated product will be mainly of interest for those users who require a fully populated image, and it may be particularly useful for large-scale, regional studies requiring high temporal sensitivity.
A gap mask, which allows the user to identify all interpolated vs. actual data values, is provided with every SLC-off interpolated product.
To download samples of the SLC-off products, see the Sample Products page.
All SLC-off data products may be searched and ordered through EarthExplorer or the USGS Global Visualization Viewer (GloVis)
The distribution of Landsat 7 ETM+ L1Gt and L1T Terrain correction data is restricted to U. S. Government and its affiliated users. Please contact USGS EROS Customer Services if you have questions regarding this policy.
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U.S. Geological Survey
URL: http://landsat.usgs.gov
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Page Contact Information: landsat@usgs.gov
Page Last Modified: May 12, 2008
