GIS Ag Maps Image-Based DOS Landsat 8 Surface Reflectance (SR) Results & Validation
(Values below are based on the Original Relative Scatter Table using the Lowest Valid Value Scatter Method)
The GIS Ag Maps dark-object subtraction (DOS) (concept originated in Chavez [1988]) Landsat 8 SR method is a simple and fast technique that establishes scatter by specific techniques (uses relative scatter) that are described and can be accessed through the Tutorial. The NDVI values in this article are based on the Original Relative Scatter Lookup Table; the current Revised Table is the same for the red band, while the NIR band has slightly lower scatter values; so the NDVI values would be slightly higher. The following article in Remote Sensing of Environment (Ke et al., 2015) examines and validates GIS Ag Maps DOS SR (page 303 [2.5.2]; labeled Landsat DOS on the graphic below) when applied to NDVI by comparing DOS-based Normalized Difference Vegetation Index (NDVI) values (as well as NDVI values from other reflectance methods and sensors) to in-situ NDVI measurements on a different continent (opens in new tab): Characteristics of Landsat 8 OLI-derived NDVI by comparison with multiple satellite sensors and in-situ observations.
GIS Ag Maps Lowest Valid Value Attribute Table Method is used for Landsat 8 DOS below (explained in article)
In the graphic above (Figure 10 from Ke et al. 2005), which can be accessed articles made accessible above, Landsat DOS (lighter orange) is GIS Ag Maps DOS SR method (as named and described in article), others are as follows: LED is an in-situ NDVI measurement based on light emitting diode instrumentation. Landsat TOA is Top of Atmosphere reflectance (not surface reflectance); Landsat 6SV is Second Simulation of a Satellite Signal in the Solar Spectrum Vector radiative transfer algorithm surface reflectance; Landsat FLAASH is Fast Line-of-sight Atmospheric Analysis of Hypercubes surface reflectance; MODIS is Moderate Resolution Imaging Spectroradiometer; GOCI is Geostationary Ocean Color Imager.
Comparison Between USGS & GIS Ag Maps Landsat 8 Surface Reflectance for Cloud - Free Areas
Related Pages: Landsat 8 SR Tutorial w/ Imagery Download Relative Scatter Lookup Table
The GIS Ag Maps DOS SR method uses continuous relative scatter which was suggested in Chavez (1988) and applied in Hollinger (2009). The table below shows a comparison of average surface reflectance and standard deviation for five areas (different dates and locations) that are shown below the table (abbreviation meanings are listed below table). Image-based methods to convert Landsat 8 digital numbers to surface reflectance were published on this website well before Landsat 8 surface reflectance was made available by the USGS. Surface reflectance retrieved by methods here based on a Continuous Relative Scatter Table are compared to USGS surface reflectance below - an adjustment is made to green scatter in the original scatter table in order to make green values closer to USGS Landsat 8 Algorithm surface reflectance (which is not solely DOS-based; abbreviated in table as DOS2 SR). DOS1 SR is the same as DOS2 SR, with the exception that DOS1 SR does not apply the modified green scatter (DOS1 SR is different than DOS SR because DOS1 SR uses TOA for NIR surface reflectance, while DOS SR applies relative scatter for NIR). Converting to surface reflectance independently can be useful if, for example, surface reflectance is not available for a particular reason or scene, or if surface reflectance is needed as soon as possible. See bottom of page for green scatter adjustment methodology.
Average of Green Mask Extent of Five Areas Below
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0176 | 0.0207 | 0.0207 | 0.0944 | ||
| B3 (Green) | 0.0420 | 0.0361 | 0.0420 | 0.0792 | ||
| B4 (Red) | 0.0242 | 0.0240 | 0.0240 | 0.0501 | ||
| B5 (NIR) | 0.4537 | 0.4525 | 0.4525 | 0.4525 | ||
| B6 (SWIR) | 0.1774 | 0.1728 | 0.1728 | 0.1728 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0026 | 0.0026 | 0.0026 | 0.0026 | ||
| B3 (Green) | 0.0056 | 0.0047 | 0.0047 | 0.0047 | ||
| B4 (Red) | 0.0049 | 0.0043 | 0.0043 | 0.0043 | ||
| B5 (NIR) | 0.0540 | 0.0535 | 0.0535 | 0.0535 | ||
| B6 (SWIR) | 0.0287 | 0.0273 | 0.0273 | 0.0273 |
Average of Full Extent of Five Areas Below
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0280 | 0.0279 | 0.0279 | 0.1016 | ||
| B3 (Green) | 0.0558 | 0.0467 | 0.0525 | 0.0898 | ||
| B4 (Red) | 0.0442 | 0.0407 | 0.0407 | 0.0668 | ||
| B5 (NIR) | 0.4051 | 0.4049 | 0.4049 | 0.4049 | ||
| B6 (SWIR) | 0.2113 | 0.2051 | 0.2051 | 0.2051 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0156 | 0.0120 | 0.0120 | 0.0120 | ||
| B3 (Green) | 0.0206 | 0.0164 | 0.0164 | 0.0164 | ||
| B4 (Red) | 0.0290 | 0.0247 | 0.0247 | 0.0247 | ||
| B5 (NIR) | 0.0786 | 0.0771 | 0.0771 | 0.0771 | ||
| B6 (SWIR) | 0.0600 | 0.0572 | 0.0572 | 0.0572 |
USGS SR is surface reflectance based on the USGS Landsat 8 Algorithm that can be ordered and downloaded for free. DOS1 SR uses the Relative Scatter Lookup Table to deduct blue and green scatter based on red starting scatter and uses TOA for NIR reflectance (DOS SR, included in Tutorial also applies relative scatter to the NIR band). DOS2 SR the same as DOS1 SR with adjusted green band scatter (Green 2) in the Relative Scatter Lookup Table. THE METHODOLOGY FOR THE ADJUSTED GREEN BAND VALUE IS SHOWN AT THE BOTTOM OF THIS PAGE. The Relative Scatter Lookup Table simplifies the conversion process for the visible bands and makes the process more reliable. TOA is top of the atmosphere reflectance (not surface reflectance) that can be calculated based on a published USGS equation. TOA reflectance is used for the NIR and SWIR bands as these values are shown to be closer to USGS values. "B" is band. Stan. Dev. is the average standard deviation of the five areas below. (DOS SR is not included here, but is included in the Tutorial; DOS SR is the same as DOS1 SR, except it also has relative scatter deducted from the NIR band.)
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Individual Areas and Dates for Reflectance Comparison
(in order of clearest atmosphere based on Lowest Valid Value (also know as the DN100 Method) red band reflectance scatter; background image is LandsatLook for particular scene)
Red Band Scatter (.011561)
August 4th, 2015; Northwest Ohio, USA (orange extent; 29.0 km x 13.8 km)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0306 | 0.0369 | 0.0369 | 0.0945 | ||
| B3 (Green) | 0.0592 | 0.0566 | 0.0577 | 0.0859 | ||
| B4 (Red) | 0.0503 | 0.0546 | 0.0546 | 0.0661 | ||
| B5 (NIR) | 0.3662 | 0.3669 | 0.3669 | 0.3669 | ||
| B6 (SWIR) | 0.2041 | 0.1973 | 0.1973 | 0.1973 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0178 | 0.0145 | 0.0145 | 0.0145 | ||
| B3 (Green) | 0.0223 | 0.0184 | 0.0184 | 0.0184 | ||
| B4 (Red) | 0.0337 | 0.0296 | 0.0296 | 0.0296 | ||
| B5 (NIR) | 0.0721 | 0.0711 | 0.0711 | 0.0711 | ||
| B6 (SWIR) | 0.0560 | 0.0538 | 0.0538 | 0.0538 |
Green Mask (more than 99.99% of pixels within gray area have higher green reflectance than blue or red)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0191 | 0.0284 | 0.0284 | 0.0861 | ||
| B3 (Green) | 0.0451 | 0.0456 | 0.0466 | 0.0749 | ||
| B4 (Red) | 0.0283 | 0.0357 | 0.0357 | 0.0472 | ||
| B5 (NIR) | 0.4256 | 0.4254 | 0.4254 | 0.4254 | ||
| B6 (SWIR) | 0.1717 | 0.1663 | 0.1663 | 0.1663 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0037 | 0.0027 | 0.0027 | 0.0027 | ||
| B3 (Green) | 0.0070 | 0.0055 | 0.0055 | 0.0055 | ||
| B4 (Red) | 0.0066 | 0.0055 | 0.0055 | 0.0055 | ||
| B5 (NIR) | 0.0455 | 0.0450 | 0.0450 | 0.0450 | ||
| B6 (SWIR) | 0.0201 | 0.0192 | 0.0192 | 0.0192 |
Red Band Scatter (.022312)
August 18th, 2014; Easter Iowa, USA (orange extent; 117 km x 194 km)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0206 | 0.0172 | 0.0172 | 0.0867 | ||
| B3 (Green) | 0.0435 | 0.0342 | 0.0388 | 0.0737 | ||
| B4 (Red) | 0.0290 | 0.0255 | 0.0255 | 0.0478 | ||
| B5 (NIR) | 0.4266 | 0.4259 | 0.4259 | 0.4259 | ||
| B6 (SWIR) | 0.1852 | 0.1791 | 0.1791 | 0.1791 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0120 | 0.0105 | 0.0105 | 0.0105 | ||
| B3 (Green) | 0.0164 | 0.0139 | 0.0139 | 0.0139 | ||
| B4 (Red) | 0.0201 | 0.0178 | 0.0178 | 0.0178 | ||
| B5 (NIR) | 0.0897 | 0.0885 | 0.0885 | 0.0885 | ||
| B6 (SWIR) | 0.0394 | 0.0378 | 0.0378 | 0.0378 |
Green Mask (more than 99.99% of pixels within gray area have higher green reflectance than blue or red)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0159 | 0.0137 | 0.0137 | 0.0832 | ||
| B3 (Green) | 0.0365 | 0.0285 | 0.0332 | 0.0681 | ||
| B4 (Red) | 0.0203 | 0.0181 | 0.0181 | 0.0404 | ||
| B5 (NIR) | 0.4693 | 0.4680 | 0.4680 | 0.4680 | ||
| B6 (SWIR) | 0.1789 | 0.1730 | 0.1730 | 0.1730 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0017 | 0.0026 | 0.0026 | 0.0026 | ||
| B3 (Green) | 0.0038 | 0.0036 | 0.0036 | 0.0036 | ||
| B4 (Red) | 0.0035 | 0.0034 | 0.0034 | 0.0034 | ||
| B5 (NIR) | 0.0729 | 0.0723 | 0.0723 | 0.0723 | ||
| B6 (SWIR) | 0.0317 | 0.0304 | 0.0304 | 0.0304 |
Red Band Scatter (.022550)
July 11th, 2013; Southern Illinois & Indiana (crosses border), USA (orange extent; 119.7 km x 35.7 km)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0376 | 0.0353 | 0.0353 | 0.1051 | ||
| B3 (Green) | 0.0710 | 0.0601 | 0.0647 | 0.0998 | ||
| B4 (Red) | 0.0647 | 0.0599 | 0.0599 | 0.0824 | ||
| B5 (NIR) | 0.3766 | 0.3777 | 0.3777 | 0.3777 | ||
| B6 (SWIR) | 0.2451 | 0.2373 | 0.2373 | 0.2373 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0241 | 0.0185 | 0.0185 | 0.0185 | ||
| B3 (Green) | 0.0332 | 0.0268 | 0.0268 | 0.0268 | ||
| B4 (Red) | 0.0472 | 0.0408 | 0.0408 | 0.0408 | ||
| B5 (NIR) | 0.0821 | 0.0808 | 0.0808 | 0.0808 | ||
| B6 (SWIR) | 0.0894 | 0.0856 | 0.0856 | 0.0856 |
Green Mask (more than 99.99% of pixels within gray area have higher green reflectance than blue or red)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0165 | 0.0202 | 0.0202 | 0.0900 | ||
| B3 (Green) | 0.0413 | 0.0368 | 0.0414 | 0.0765 | ||
| B4 (Red) | 0.0235 | 0.0248 | 0.0248 | 0.0473 | ||
| B5 (NIR) | 0.4405 | 0.4407 | 0.4407 | 0.4407 | ||
| B6 (SWIR) | 0.1753 | 0.1705 | 0.1705 | 0.1705 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0033 | 0.0037 | 0.0037 | 0.0037 | ||
| B3 (Green) | 0.0074 | 0.0066 | 0.0066 | 0.0066 | ||
| B4 (Red) | 0.0063 | 0.0057 | 0.0057 | 0.0057 | ||
| B5 (NIR) | 0.0488 | 0.0484 | 0.0484 | 0.0484 | ||
| B6 (SWIR) | 0.0304 | 0.0291 | 0.0291 | 0.0291 |
Red Band Scatter (.032949)
July 30th, 2014; East Central Illinois, USA (orange extent; 23.7 km x 15.0 km)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0195 | 0.0221 | 0.0221 | 0.1033 | ||
| B3 (Green) | 0.0433 | 0.0356 | 0.0437 | 0.0852 | ||
| B4 (Red) | 0.0258 | 0.0232 | 0.0232 | 0.0562 | ||
| B5 (NIR) | 0.4981 | 0.4959 | 0.4959 | 0.4959 | ||
| B6 (SWIR) | 0.1838 | 0.1794 | 0.1794 | 0.1794 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0102 | 0.0073 | 0.0073 | 0.0073 | ||
| B3 (Green) | 0.0135 | 0.0102 | 0.0102 | 0.0102 | ||
| B4 (Red) | 0.0173 | 0.0141 | 0.0141 | 0.0141 | ||
| B5 (NIR) | 0.0806 | 0.0798 | 0.0798 | 0.0798 | ||
| B6 (SWIR) | 0.0429 | 0.0406 | 0.0406 | 0.0406 |
Green Mask (more than 99.99% of pixels within gray area have higher green reflectance than blue or red)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0160 | 0.0198 | 0.0198 | 0.1010 | ||
| B3 (Green) | 0.0384 | 0.0320 | 0.0402 | 0.0817 | ||
| B4 (Red) | 0.0195 | 0.0183 | 0.0183 | 0.0512 | ||
| B5 (NIR) | 0.5224 | 0.5199 | 0.5199 | 0.5199 | ||
| B6 (SWIR) | 0.1772 | 0.1732 | 0.1732 | 0.1732 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0011 | 0.0011 | 0.0011 | 0.0011 | ||
| B3 (Green) | 0.0034 | 0.0030 | 0.0030 | 0.0030 | ||
| B4 (Red) | 0.0021 | 0.0018 | 0.0018 | 0.0018 | ||
| B5 (NIR) | 0.0671 | 0.0670 | 0.0670 | 0.0670 | ||
| B6 (SWIR) | 0.0389 | 0.0368 | 0.0368 | 0.0368 |
Red Band Scatter (.041205)
July 10th, 2014; North Central Iowa, USA (orange extent; 68.2km x 37.1 km)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0320 | 0.0281 | 0.0281 | 0.1185 | ||
| B3 (Green) | 0.0619 | 0.0468 | 0.0576 | 0.1043 | ||
| B4 (Red) | 0.0510 | 0.0402 | 0.0402 | 0.0814 | ||
| B5 (NIR) | 0.3579 | 0.3581 | 0.3581 | 0.3581 | ||
| B6 (SWIR) | 0.2384 | 0.2322 | 0.2322 | 0.2322 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0141 | 0.0094 | 0.0094 | 0.0094 | ||
| B3 (Green) | 0.0175 | 0.0126 | 0.0126 | 0.0126 | ||
| B4 (Red) | 0.0269 | 0.0213 | 0.0213 | 0.0213 | ||
| B5 (NIR) | 0.0683 | 0.0655 | 0.0655 | 0.0655 | ||
| B6 (SWIR) | 0.0724 | 0.0684 | 0.0684 | 0.0684 |
Green Mask (more than 99.99% of pixels within gray area have higher green reflectance than blue or red)
| Landsat 8 | USGS SR | DOS1 SR | DOS2 SR | TOA | ||
| B2 (Blue) | 0.0208 | 0.0213 | 0.0213 | 0.1116 | ||
| B3 (Green) | 0.0486 | 0.0376 | 0.0485 | 0.0951 | ||
| B4 (Red) | 0.0293 | 0.0233 | 0.0233 | 0.0645 | ||
| B5 (NIR) | 0.4105 | 0.4086 | 0.4086 | 0.4086 | ||
| B6 (SWIR) | 0.1839 | 0.1808 | 0.1808 | 0.1808 | ||
| Landsat 8 | Stan. Dev. | Stan. Dev. | Stan. Dev. | Stan. Dev. | ||
| B2 (Blue) | 0.0034 | 0.0030 | 0.0030 | 0.0030 | ||
| B3 (Green) | 0.0062 | 0.0048 | 0.0048 | 0.0048 | ||
| B4 (Red) | 0.0060 | 0.0049 | 0.0049 | 0.0049 | ||
| B5 (NIR) | 0.0357 | 0.0348 | 0.0348 | 0.0348 | ||
| B6 (SWIR) | 0.0225 | 0.0212 | 0.0212 | 0.0212 |
Green Scatter Adjustment for DOS2 SR Methodology
A quite statistically significant correlation exists between the red band starting scatter amount (shown above) and the difference between USGS B2 (green) SR and DOS B2 SR (USGS - PM), as is shown below. In the plot: x-axis is red band scatter; y-axis is the different between USGS SR B2 and DOS SR B2 (USGS - DOS). Red band scatter was input into the linear regression equation below to calculate the amount that was added to DOS B2 to derive DOS2 B2.
References
Chavez, P.S., Jr. 1996. Image-based atmospheric corrections–revisited and improved. Photogrammetric Engineering and Remote Sensing 62(9): pp.1025-1036.
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.
Hollinger, D. 2009. A GIS-based method to predict county corn yield based on retrieved Landsat reflectance variability in western Ohio. Papers of the Applied Geography Conference 32: pp.281-290.
Ke, Y., Im, J., Lee, J., Gong, H., and Y. Ryu. 2005. Characteristics of Landsat 8 OLI-derived NDVI by comparison with multiple satellite sensors and in-situ observations. Remote Sensing of Environment 164: pp. 298-313.