Land/Water Mask Algorithm Specification

Algorithm Specification

The Land/Water Mask Algorithm takes the geographic bounds of the input product and creates a new product covering the same area. The output product contains a single band, which indicates if a pixel is land or water. For each pixel, it contains the fraction of water; a value of 0.0 indicates land, a value of 100.0 indicates water, and every value in between indicates a mixed pixel.
Since the base data may exhibit a higher resolution than the input product, a subsampling ≥1 may be specified. In this case for each resulting sub-pixel the it is computed if its land or water. Averaging the sub-pixel gives the fraction of water covered by the macro-pixel.
There are two auxiliary data sets on which the watermask can be based.

High-Resolution Dataset

The high-res dataset is based on data given by SRTM -shapefiles between 60° north and 58° south, and by the world map above 60° north. Below 58° south, this dataset does not contain any data, so the resulting product will contain the fill value for these parts. This high-res dataset will be employed when the resolution parameter is set to 50m or 150m.

Low-Resolution Data Set

The second dataset is based on data in a resolution of 1 km. It covers the whole earth, and will be employed when the resolution parameter is set to 1000.