% Function to return a SGL mask based on a specified NDWI threshold, and % using the red and blue bands of Sentinel-2 or Landsat-8 (both work in the % same way...) function NDWI_defined_SGLs = S2_NDWI(blue_band,red_band,NDWI_threshold) % get the NDWI (standard approach) NDWI_definition = (blue_band - red_band) ./ (blue_band + red_band); NDWI_defined_SGLs = zeros(size(blue_band)); % pre-allocate % mask lake areas based on this NDWI_defined_SGLs(NDWI_definition >= NDWI_threshold) = 1; % show a figure of the lake mask imagesc(NDWI_defined_SGLs) end