Saturday, February 27, 2016

Surface Reflectance in ArcGIS

I just noticed that at the recent version, ArcGIS has been implemented some sort of physical liked surface reflectance generation function in its image analysis module. The function is called apparent surface reflectance. An algorithm which takes into consideration all the iradiance related information stored in the metadata (sun azimuth angle, sun elevation angle, radiance gain/bias etc) to derive surface reflectance dataset, although it is not pure physical (because it does not consider the atmospheric condition at the acquisition date). The algorithm target the illumination condition which is theoretically should be similar between dates and wavelengths (differs in reality due to atmospheric effects, sun angle/position and sun-earth distance in every season etc) so it could be usable for color balancing and mosaicking (not sure if it will add certain degrees of accuracy in image classification).

I make a guide if you want to try it by yourself