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stac-extensions / eo

Covers electro-optical data that represents a snapshot of the Earth. It could consist of cloud cover and multiple spectral bands, for example visible bands, infrared bands, red edge bands and panchromatic bands.
Apache License 2.0
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Calculation of eo:cloud_cover #25

Closed drnextgis closed 3 months ago

drnextgis commented 1 year ago

Should the eo:cloud_cover percentage be calculated for the entire raster or exclusively for the valid data regions (excluding "nodata" areas)? In the given example, the black regions represent areas not captured by a satellite. It's crucial to determine whether these areas should be factored in when calculating eo:cloud_cover, as this could yield markedly different results. If nodata areas are excluded and cloud coverage is computed solely over valid regions, the percentage will approach 100%. Conversely, if nodata areas are included, the percentage will be substantially lower. image

matthewhanson commented 1 year ago

@drnextgis The cloud cover should be the percent of the valid data area covered by clouds. This way it will provide a normalized metric for the clouds, otherwise it could heavily depend on how well an image fits into a north-up rectangle and wouldn't be a great metric for cloud cover.

drnextgis commented 1 year ago

@matthewhanson, I appreciate your prompt response! Would it be alright if I leave this ticket unresolved until we provide further clarification in the README file? The current information there isn't very clear:

Estimate of cloud cover as a percentage (0-100) of the entire scene.