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Landsat
Processing Level
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Landsat data are typically available with three levels of processing.
Level Ø Reformatted
(ØR, RAW)
Pixels are neither resampled nor are they geometrically corrected or registered, i.e. the pixels are not aligned per scan line. Any radiometric artefacts such as impulse noise, coherent noise, memory effects, etc. are still present in any Level 0R image. This product is for users able to do all the processing themselves.
Level 1 Radiometrically
Corrected (1R, RADCOR)
The Level 1R product is a radiometrically corrected ØR product, which corrects detector artifacts such as coherent noise, improves cosmetic artifacts such as banding, striping, and dropped lines or pixels, and is calibrated to radiance units, i.e. colour corrected, as integer values. Radiometric corrections are not reversible. As for the Level ØR product, pixels are neither resampled nor are they geometrically corrected or registered, i.e. the pixels are not aligned per scan line—see image below. This product also requires extensive processing by the user.
Level 1 System
Corrected (1G)
The Level 1G product should be considered the standard product for most users. It is radiometrically and geometrically corrected to user-specified parameters, including output map projection, image orientation (defaults are UTM and WGS84), and resampling algorithm (Nearest Neighbour or Cubic Convolution). No atmospheric corrections are applied to the images.
The System Corrected product is free from distortions related to the sensor (e.g., jitter, view angle effect), satellite (e.g., attitude deviations from nominal), and Earth (e.g., rotation, curvature). Residual error in the systematic 1G product is less than 250 metres for Landsat 7 (more for other Landsat missions) in flat areas at sea level. Absolute location is better (circa 100 metres) with post-pass processing using the definitive efemeris.
System Corrected images can be produced
with 2 different orientations: path oriented
(SYSCOR), that displays on the same rows
the satellite acquisition scan lines, or
map oriented (GEOREF—for full scenes only)
with north-up display.
The 1G System Corrected product does not employ ground control or relief models to obtain absolute geodetic accuracy. More accurate processing (up to orthocorrection with the use of GCPs and DEM) is available as an additional service.
(left) Level 0R, RADCOR or 1R images have unaligned scan lines
(right) System Corrected (Level
1G) with aligned, resampled pixels
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