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Crop Agriculture

Landsat 8 Dark Object Examples

The images below show points centered on Landsat 8 pixels that have very low relative values in the blue, green, and red bands for entire Landsat 8 scenes, and are essentially dark objects. (Google Earth background imagery is shown, as opposed to the Landsat imagery, in order to have a high resolution view of surface.) The amount of total nonzero values is the amount of pixels with nonzero values and can change a relatively small amount from scene to scene; the amount of different values can change relatively more.

 

4/17/13: not in shadow in Landsat image

Blue DN value is 8,090; 38,790,925 of the total 38,790,944 nonzero pixels have higher value; 14th lowest value out of 16,582 different values. Green DN value is 6,824; 38,792,060 of the total 38,792,061 nonzero pixels have higher value; the lowest value out of 17,942 different values. Red DN value is 6,214; 38,791,779 of the total 38,791,785 nonzero pixels have higher value; 6th lowest value out of 19,796 different values.  

Dark object for dark object subtraction (DOS) scatter establishment for atmospheric correction and surface reflectance

 

6/20/13: in cloud shadow in Landsat image

Blue DN value is 8,231; 38,778,443 of the total 38,778,466 nonzero pixels have higher value; 15th lowest value out of 23,107 different values. Green DN value is 7,035; 38,779,506 of the total 38,779,532 nonzero pixels have higher value; 20th lowest value out of 24,768 different values. Red DN value is 6,120; 38,779,252 of the total 38,779,272 nonzero pixels have higher value; 12th lowest value out of 27,258 different values. 

Dark object for dark object subtraction (DOS) scatter establishment for atmospheric correction and surface reflectance

 

7/18/13: in cloud shadow in Landsat image

Blue DN value is 8,040; 41,634,923 of the total 41,634,931 nonzero pixels have higher value; 7th lowest value out of 52,089 different values. Green DN value is 6,914; 41,636,179 of the total 41,636,182 nonzero pixels have higher value; 3rd lowest value out of 52938 different values. Red DN value is 6137; 41,635,866 of the total 41,635,891 nonzero pixels have higher value; 16th lowest value out of 55,686 different values.  

Dark object for dark object subtraction (DOS) scatter establishment for atmospheric correction and surface reflectanc

 

8/23/13: in cloud shadow in Landsat image

Blue DN value is 8,014; 41,657,020 of the total 41,657,031 nonzero pixels have higher value; 11th lowest value out of 38,579 different values. Green DN value is 6,780; 41,658,217 of the total 41,658,218 nonzero pixels have higher value; the lowest value out of 40,001 different values. Red DN value is 6,013; 41,657,900 of the total 41,657,920 nonzero pixels have higher value; 19th lowest value out of 43,269 different values.  

Dark object for dark object subtraction (DOS) scatter establishment for atmospheric correction and surface reflectanc


 

 

Reference

Chavez, P.S., Jr. 1988. An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data. Remote Sensing of Environment 24: pp.459-479.