How is the Surface Reflectance Product Provided?

Planet's Surface Reflectance (SR) product is provided as a 16-bit GeoTIFF image with reflectance values scaled by 10,000 in order to increase efficiency in product retrieval. Planet also includes associated metadata describing inputs to the correction in a TIFFTAG_IMAGEDESCRIPTION metadata header. 

If you wish to confirm that is a surface reflectance image with the atmospheric corrections applied, the header of the GeoTIFF image can be checked.


You can do that in QGIS by looking in the layer properties of the raster file.

Properties QGIS.jpg


You can also use GDAL to read the header using the following command:

from osgeo import gdal
metadata = gdal.Info(r"file_path_image.tif")
print (metadata)

ArcGIS Pro:

To view the metadata in ArcGIS Pro you will need to carry out a small additional step. Unlike in QGIS where the layer properties contain this information, ArcGIS does not display this directly in the UI of the layer properties.

1. To view the metadata supplied with our Surface Reflectance assets, please click on Insert-> New Notebook.


2. Once you have done that, a Jupyter notebook interface allows you to write python commands. Here we will be using GDAL which is used by QGIS to render the information in the layer properties UI.

from osgeo import gdal
metadata = gdal.Info(r"file_path_image.tif")
print (metadata)



Note on reflectance values: Due to the scaling factor, bands have to be divided by 10,000 when we are doing an addition or subtraction in the computation of vegetation indices.  For example, you can obtain EVI and EVI2 using our bandmath tool or in QGIS using the following formulas in the raster calculator tool:

General formulas:
EVI (Enhanced Vegetation Index): 2.5 * (NIR - RED) / ((NIR + 6*RED - 7.5*BLUE) + 1)
EVI2 (Enhanced Vegetation Index 2): 2.4 * (NIR - RED) / ((NIR + RED + 1)
Computation in bandmath tool or in QGIS via the raster calculator tool specific to Planet Surface Reflectance data
EVI: 2.5*(((b8/10000)-(b6/10000))/((b8/10000)+6*(b6/10000)-7.5*(b2/10000)+1))
EVI2: 2.4*(((b8/10000)-(b6/10000))/((b8/10000)+(b6/10000)+1))

The above example considers an 8 band "PSScene" Surface Reflectance asset, where the 8 band multispectral order is as follows:

Band 1 = Coastal Blue
Band 2 = Blue
Band 3 = Green I
Band 4 = Green
Band 5 = Yellow
Band 6 = Red
Band 7 = Red Edge
Band 8 = Near-infrared

For detailed information, please refer to the Planet Surface Reflectance Documentation.

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