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Collection 1.0 vs. Collection 1.1

Collection 1.1, released in Spring 2021, is an update to the LCMAP CONUS Science Products Collection 1.0. The new Collection contains 10 science products for the years 1985-2019, based on the implementation of the LCMAP Continuous Change Detection and Classification (CCDC) algorithm. Collection 1.1 includes non-provisionary 2017 products, 2018 products, and provisional 2019 products. Collection 1.1 also contains updates to other product years resulting from additional Landsat Analysis Ready Data (ARD) for 2018 and 2019  and refitting of end models in the previous collection. 

LCMAP 1.1 updates: 

  • The input Landsat ARD observations are consistent with Collection 1.0 input over the corresponding time period (1982 thru the end of 2017), except for the four tiles listed under the caveats and constraints section on the Collection 1.1 page
  • The change detection algorithm (PYCCD) was updated to constrain statistical calculations. This limited forward processing by only applying the algorithm to observations occurring after the most recent break in Collection 1.0 (LCMAP Collection 1.1 CCDC ADD Section 2.5.6). 
  • The supervised learning classification model developed for Collection 1.0 was used to classify the land cover in Collection 1.1 (LCMAP Collection 1.1 CCDC ADD Section 3.5.4).

What is contained in LCMAP Collection 1.1? 

LCMAP Collection 1.1 contains the same 10 data products as Collection 1.0. Collection 1.1 is based on Landsat ARD through the year 2019. This results in in annual products for the years 1985 to 2019, including non-provisional 2017 products, and provisional 2019 products. 

Are there any data format changes? 

There are no data format changes between the collections. 

Why an entire new collection? Why can’t I simply add the new years to the previous products I already downloaded? 

By extending the temporal sequence of data, previous change detection harmonics and land cover classifications may be impacted. How far back changes may be seen is dependent on the last spectral break for any given pixel location. Data prior to the last spectral break for a pixel location does not change between the two datasets, except for the four tiles listed under the caveats and constraints section on the Collection 1.1 page.

See sections 2.5.6 and 3.5.4 from the LCMAP CCDC Collection 1.1 ADD and section 4.1.1 from the LCMAP Collection 1.1 Science Product Guide for further discussion.

Can 1.1 and 1.0 products/years be used interchangeably?  

We recommend that users use the latest data, as additional information helps overcome errors in previously released collections. 

What changes can users expect to see? 

Users can expect to see updated land cover information, as two additional years of observations add more information for the harmonic model fits, especially after the last model break recorded in Collection 1.0. The additional observations in Collection 1.1 can cause a land cover class to be different than what was predicted in Collection 1.0.