Earthdata Forum

Dear all,
Hi!
I used SeaDAS(v8.0) l2gen (oli module) to process with Landsat8 Collection1 data and obtained Lt data successfully. However, when I compared Lt from SeaDAS with Lt calculated directly from DN data, I found they were obviously different (pleased see the attached image). The original data I downloaded from USGS is : LC08_L1GT_122048_20130521_20170504_01_T2, and the results shown in the attached image is based on band5.
I am not sure what caused this kind of difference, so I write to find help.
I am looking forward to your reply and appreciate your kindly help.
Best wishes,
Roxani

Roxani,

The l2gen code uses the reflectance formula and computes Lt from that. Similar to the approach described here:
https://www.usgs.gov/core-science-syste ... ta-product

There is also a correction applied for the various focal plane modules and an overall vicarious calibration applied.

The result is consistent with the Lt generated by other sensors we support (e.g. a coincident MODIS scene provides comparable Lts)

Sean