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worldbank / blackmarblepy

Georeferenced Rasters and Statistics of Nightlights from NASA Black Marble
https://worldbank.github.io/blackmarblepy/
Mozilla Public License 2.0
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ntl_mean #54

Open Abdulazizbek opened 5 months ago

Abdulazizbek commented 5 months ago 
data = bm_extract(roi = gdf, 
                      product_id = "VNP46A2",
                      date_range = pd.date_range("2021-10-02", "2021-11-01", freq="D"), 
                      bearer = bearer,
                     )

When download data, it provides ntl_mean value. I have found some additional information what does it mean: ntl_mean, but I'm not sure. My question is: what is the exact interpretation of ntl_mean: Thank you beforehand,

g4brielvs commented 4 months ago

@Abdulazizbek Thanks! BlackMarblePy's bm_extract returns zonal statistics. Zonal statistics summarize raster data by aggregating (e.g., adding up) the values of the raster cells that fall within each zone defined by the vector geometries. By default (see documentation), the average is be returned. You may select other valid functions, e.g., sum or median.

Abdulazizbek commented 4 months ago

Thank you for detailed explanation. Is it possible to interpret ntl_mean value from bm_extract (unit of the lights measured in nighttime lights?) like this version: (Giga) Watts luminosity for NxN km