Dear Edzer, Thank you for your reply and the suggestions. Apologies for not copying the list, I forgot to hit 'reply all'.
The data is Nighttime lights from Black Marble. Source of the geo-location data (VNP03DNB): https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/VNP03DNB/ Observation data (VNP02DNB): https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/VNP02DNB/ Thank you for the code, I only changed the path but I am getting the following error when I run the following part; latlon = read_stars( c('NETCDF:"VNP03DNB.A2020015.0236.001.2020044182419.nc ":/geolocation_data/latitude', 'NETCDF:"VNP03DNB.A2020015.0236.001.2020044182419.nc ":/geolocation_data/longitude')) "Error in CPL_read_gdal(as.character(x), as.character(options), as.character(driver), : file not found" I checked the path. Thank you again. Best, Milu On Fri, Mar 20, 2020 at 9:27 AM Edzer Pebesma <edzer.pebe...@uni-muenster.de> wrote: > Dear Milu, > > It is more practical for yourself and more helpful for others when you > reply to the list. I now Cc: the list, but that is not how it is > supposed to work. Also, please use text mails, not html with inline > links. Finally, your links point to things you downloaded and > reuploaded, not to the place where you got the dataset from - for future > users having the same problem and consulting mailing list archives this > is also not really helpful. > > I tried this: > > # maybe: remotes::install_github("r-spatial/stars") > library(stars) > r = read_stars("VNP02DNB_NRT.A2020069.1048.001.nc") > latlon = read_stars( > c('NETCDF:"VNP03DNB.A2020015.0236.001.2020044182419.nc > ":/geolocation_data/latitude', > 'NETCDF:"VNP03DNB.A2020015.0236.001.2020044182419.nc > ":/geolocation_data/longitude')) > r_ll = st_as_stars(r, > curvilinear = list(x = latlon[[2]], y = latlon[[1]])) > plot(r_ll, reset = FALSE, axes = TRUE) > maps::map('world', add = TRUE, col = 'red') > > Although I don't really know what the data is about, the plot generated > (attached) to me seems to indicate that you are trying to glue the wrong > latitudes and longitudes to your measurements. > > > > On 3/19/20 11:29 PM, Miluji Sb wrote: > > Thank you for your reply and the information. > > > > This file > > <https://drive.google.com/open?id=1zpqXJ8AlEcnk6ApRb75tfQc4-Y8AfK5h > > needs > > to be combined with the geo-location data in this file > > <https://drive.google.com/open?id=1jLmXLjG0WGgdH3g4pGJNz0ZOqXOfKpcW>. I > > will try out the stars package, any suggestions will be highly > appreciated. > > > > Thanks again and stay safe. > > > > Best, > > > > Milu > > > > On Wed, Mar 18, 2020 at 5:25 PM Edzer Pebesma > > <edzer.pebe...@uni-muenster.de <mailto:edzer.pebe...@uni-muenster.de>> > > wrote: > > > > If the product info is in this document: > > > https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/viirs/NASAVIIRSL1BUGAug2019.pdf > > > > then it sounds like these data are distributed as curvilinear grids, > > meaning that there are two additional raster with for each pixel the > > longitude and the latitude. The file you pointed to does not contain > > these two grids, but you should be able to get them at the place > where > > you got the data. With that, you can use package stars to load them, > and > > e.g. resample to some (more) regular grid. > > > > See e.g. > > > https://r-spatial.github.io/stars/articles/stars4.html#curvilinear-grids > > > > On 3/18/20 3:29 PM, Michael Sumner wrote: > > > 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 > > <mailto: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 > > <http://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 > > <http://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 <mailto:R-sig-Geo@r-project.org> > > >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo > > >> > > > > > > > > > > -- > > Edzer Pebesma > > Institute for Geoinformatics > > Heisenbergstrasse 2, 48149 Muenster, Germany > > Phone: +49 251 8333081 > > _______________________________________________ > > R-sig-Geo mailing list > > R-sig-Geo@r-project.org <mailto:R-sig-Geo@r-project.org> > > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > > > > -- > Edzer Pebesma > Institute for Geoinformatics > Heisenbergstrasse 2, 48149 Muenster, Germany > Phone: +49 251 8333081 > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo