I am trying to convert pixel DNs to reflectance from a Planet BGRN Analytic Scene (from 2016, I can't tell what level it is processed to). However, I can't find info on the exo-atmospheric irradiance of the 4 bands. Is this available somewhere?
[GIS] Converting DNs to radiance and reflectance for Planet Labs Imagery
planetreflectance
Best Answer
If the file contains "DN" in the name then it is not scaled radiance and there is are no coefficients available to scale to scale to exo-atmospheric irradiance.
If the product is the "analytic" asset from the PSScene4Band type the filename should include "_3B_AnalyticMS" and it is scaled radiance.
If the product is the "analytic" asset from the PSOrthoTile type the filename should include "_BGRN_Analytic" and it is scaled radiance.
If you have a scaled radiance product, you can multiple by 0.01 to convert the 16bit pixels values to watts per steradian per square meter (W/m²srμm).
If you want to convert to convert to top of atmosphere reflectance, you will need to multiply by the value of the "reflectanceCoefficient" from the associated _metadata.xml file. Note that you do not compose the radiometricScaleFactor (0.01) and the reflectanceCoefficient - just multiple the original pixels values from the analytic files by hte reflectanceCoefficient. This ought to be covered page 32 of https://www.planet.com/products/satellite-imagery/files/1611.09_Spec_Sheet_Combined_Imagery_Product_Letter_DraftV3.pdf or perhaps there is a more recent version that did not come up in my google search.