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Land/water-mask
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Land/water-mask
9/19/14 5:04 AM
Hi,

I used the Land/water-mask in BEAM and I was really impressed by the results. I am just wondering what kind of method / algorithm is behind this plugin?

Thanks and best wishes,
Doreen
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RE: Land/water-mask
9/19/14 10:13 AM as a reply to Doreen Groth.
Hi Doreen,

from the documentation:

The LandWaterMask operator takes the geographic bounds of the input product and creates a new product with the same bounds. The output product contains a single band, which is the water fraction of a pixel. 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.

There are two auxiliary data sets on which the water-mask can be based. The first, high-res dataset is based on data given by SRTM-shapefiles between 60° north and 58° south, and by the GlobCover 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 50 or 150. The second dataset is based on GSHHS data in a resolution of 1 km. It covers the whole earth, and will be employed when the resolution parameter is set to 1000. Since the base data may exhibit a higher resolution than the input product, a subsampling >=1 may be specified. This means that mixed pixels may occur.


Does this answer your question, or do you need more details?

In any case, the software is open source, and you can check it out at https://github.com/bcdev/beam-watermask. The most relevant class is the WatermaskClassifier.

Cheers,
Thomas
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RE: Land/water-mask
9/19/14 3:51 PM as a reply to Thomas Storm.
Hi Thomas,

thanks a lot for your fast and very detailed answer!

Best wishes,
Doreen
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