Alaska Satellite Facility
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How to Terrain Correct CEOS Data

Adapted from the European Space Agency's STEP Community Platform

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Why terrain correct synthetic aperture radar (SAR) CEOS data? 

Terrain correction moves pixels to more accurately represent features such as mountains. 

This data recipe is for users who wish to terrain correct CEOS-formatted data granules for platforms including ERS-1, ERS-2, JERS-1, RADARSAT-1, and Level 1.5 ALOS PALSAR. Radiometric correction steps using the Ulander algorithm are included. However, the correction is not as accurate as that found in commercial SAR processing products. (Radiometric correction alters pixel values to more accurately reveal surface features such as vegetation and soil moisture.) You can terrain correct CEOS-format data by following the recipe on this page. Note: most ALOS PALSAR data in the ASF archive have been radiometrically terrain corrected.
 
Klamath Mountains before and after terrain correction of CEOS synthetic aperture radar (SAR) data
Before and after: Before radiometric terrain correction (RTC), Klamath Mountains in northern California appear stretched on one side and compressed on the other (left). RTC (right) moves pixels to unstretch the mountains and adjusts pixel values to subtract the effect of slopes on brightness. Left: © JAXA/METI 2008; right: ASF DAAC 2016; Includes Material © JAXA/METI 2008. 

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