How does Surface Reflectance improve on what came before it?

The standard PlanetScope products that are distributed today are radiometrically calibrated (scaled at-sensor radiance) and orthorectified using ground control points for precision correction and digital elevation models to correct for relief displacement. 6SV processes the calibrated product to surface reflectance, which enables quantifying land surface change after having normalized the data for viewing geometry, solar illumination, and atmospheric correction.