You won't find much on this kind of file in the R community, this is relatively new NetCDF-4 with "groups", and contains a satellite "granule" - a kind of pre-mapping raw data array with only technical information about where the scanning occurred.
In short, raster and stars package (and RNetCDF and ncdf4) will read the data from this file, but give very little or no help for how to treat it like a map. The spatial resolution and extent are purely nominal as shown by raster, a spacing of 1 in two dimensions and extending from 0 to nrows, 0 to ncols (with a half cell shift). There aren't any coordinate arrays in the file, or any simple way to transform from this matrix-space to geography as far as I know. (Would love to be corrected on how to do that). You'd need to pursue domain-specific expertise to discover the mapping of this, unless some kind soul turns up to help here. I expect you'll want to find a product that has been converted into simpler form for these data. Cheers, Mike. On Wed, Mar 18, 2020 at 1:39 AM Miluji Sb <miluj...@gmail.com> wrote: > Dear all, > > Hope everyone is keeping safe. > > I am trying to extract/read VIIRS nighttime lights data but the output > seems rather strange. > > I have uploaded the file here > <https://drive.google.com/open?id=1zpqXJ8AlEcnk6ApRb75tfQc4-Y8AfK5h> so as > not exceed the size limit of the email. > > ## Code ## > library(ncdf4) > library(rgdal) > > netcdf_file <- c("VNP02DNB_NRT.A2020069.1048.001.nc") > nl <- brick(netcdf_file, lvar=0, values=TRUE, > varname="observation_data/DNB_observations") > > ## Detail ## > class : RasterLayer > dimensions : 3232, 4064, 13134848 (nrow, ncol, ncell) > resolution : 1, 1 (x, y) > extent : 0.5, 4064.5, 0.5, 3232.5 (xmin, xmax, ymin, ymax) > crs : NA > source : C:/Users/shour/Desktop/VNP02DNB_NRT.A2020069.1048.001.nc > names : DNB.observations.at.pixel.locations > zvar : observation_data/DNB_observations > > The spatial resolution is supposed to be 750m but this shows 1°. What am I > doing wrong? Any help will be greatly appreciated. Thank you. > > Sincerely, > > Millu > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Michael Sumner Software and Database Engineer Australian Antarctic Division Hobart, Australia e-mail: mdsum...@gmail.com [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo