A fully automated methodology for differentiating rock from snow, clouds and sea in Antarctica from 
Landsat imagery: A new rock outcrop map and area estimation for the entire Antarctic continent

Shapefile Metadata

The shapefile (Landsat_8_Derived_Outcrop_Dataset_2016.shp) and related files enclosed in this 
compressed folder are the supplementary rock outcrop dataset associated with the following 
publication:

Burton-Johnson, A., Black, M., Fretwell, P. T., & Kaluza-Gilbert, J. (2016). A fully automated methodology for 
differentiating rock from snow, clouds and sea in Antarctica from Landsat imagery: A new rock outcrop map 
and area estimation for the entire Antarctic continent. The Cryosphere.

Refer to this publication for full details of the datasets derivation. The automated script from which 
the dataset was derived is available from: ttps://github.com/mblack2xl/AntarcticRockOutcrop. 
Please reference the associated publication when using the dataset or script in future work and 
publications.

The rock outcrop dataset was derived though automated image analysis of Landsat 8 data and 
provides an updated map of exposed rock in Antarctica at greatly improved accuracies compared to 
the previous dataset. Classification accuracy has been calculated to be 74 9% at 1 standard 
deviation error compared to 39 19% for the previous manually derived dataset.

The image analysis algorithm used to produce the updated dataset used an NDSI threshold, thermal 
infrared to blue ratio, thermal infrared threshold, an NDWI threshold and a coastal mask to identify 
sunlit rock whilst excluding sunlit snow, clouds and liquid water. In addition, a blue reflectance 
threshold, an NDWI threshold and a coastal mask were used to identify shaded rock whilst excluding 
shaded snow and liquid water. The extents of shaded and sunlit rock exposure were then merged. 
To produce the final dataset the exposed rock extents were merged with the previous manually 
derived dataset in areas lacking suitable Landsat 8 images at the time of analysis (most extensively 
south of 8240 S). These polygons are identified within the attribute table of the shapefile under the 
field Source (the origin of each polygon identified as Manually derived or Landsat 8 automated 
rock outcrop identification). To aid this differentiation the field GRIDCODE identifies 
automatically derived polygons as 1 and manually derived polygons as 0.
