My gdal 3.4.1 doesn't get the extent. I answered this (badly) on gis.stackexchange - its a 10degree tile where the origin is related to the h and v elements of the path (and also stored as attributes in the netcdf structure).
I think I messed up the vertical offset, which was because I only bothered making it work on one tile. The tile position is going to be A+Bh, C+Dv where A,B,C,D are constants, and B and D are either plus or minus 10 depending on if the origin is top or bottom or left or right, and A and C are the origins of the 0-th tiles. Once you have the origin, add 10 to get the extent. This gives the correct resolution (15 minutes of arc). Maybe tomorrow I'll get a few more tiles and write up my answer in an edit on stackex, and check all the extents etc are correct, and put my code in a function. I didn't have time to do all that previously but hoped there was enough there for understanding of the problem and anyone with a bit of maths could fix it up. Barry On Sat, Sep 9, 2023 at 9:28 PM Michael Sumner <mdsum...@gmail.com> wrote: > The extent of this one is > > 70, 80, 10, 20 > > Later versions of GDAL determine this automatically (I'm not sure when) > > rast("VNP46A3.A2018091.h25v07.001.2021125122857.h5") > class : SpatRaster > dimensions : 2400, 2400, 26 (nrow, ncol, nlyr) > resolution : 0.004166667, 0.004166667 (x, y) > extent : 70, 80, 10, 20 (xmin, xmax, ymin, ymax) > coord. ref. : lon/lat Unknown datum based upon the GRS 1980 Authalic Sphere > ellipsoid > sources : > > VNP46A3.A2018091.h25v07.001.2021125122857.h5://AllAngle_Composite_Snow_Covered > > > VNP46A3.A2018091.h25v07.001.2021125122857.h5://AllAngle_Composite_Snow_Covered_Num > > > VNP46A3.A2018091.h25v07.001.2021125122857.h5://AllAngle_Composite_Snow_Covered_Quality > ... and 23 more source(s) > varnames : AllAngle_Composite_Snow_Covered > AllAngle_Composite_Snow_Covered_Num > AllAngle_Composite_Snow_Covered_Quality > ... > > Be very careful with canned steps to "fix" georeferencing, make sure it > needs fixing and check that it's right. Ultimately the best way to "fix" it > is to go to the source of the code that interfaces the data, which here is > GDAL and report there - but clearly that's been updated from whatever > version was in use on stackoverflow. > > Cheers, Mike > . > > > > > > On Sun, Sep 10, 2023 at 1:17 AM Nikolaos Tziokas <nikos.tzio...@gmail.com> > wrote: > > > I downloaded NASA's Black Marble monthly nighttime light NTL data, > VNP46A3 > > < > > > https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/VNP46A3/ > > >. > > In a previous question > > < > > > https://gis.stackexchange.com/questions/466571/extent-not-found-on-nasas-black-marble-monthly-images-how-to-set-it/466574?noredirect=1#comment761916_466574 > > > > > of mine the reprojection worked perfectly but now it seems that it > doesn't. > > For example, I wanted to download NTL data for the city of Mumbai, India. > > After reprojecting the NTL (product 5 (All_Angles_Snow_Free) from the > .h5) > > the result is attached here > > < > https://drive.google.com/drive/folders/1V115zpdU2-5fXssI6iWv_F6aNu4E5qA7 > > >. > > > > At the bottom if the image is a shp of Mumbai (downloaded from GADM) and > > the red circle in the top indicates where Mumbai is in the NTL image. > > Clearly something's not right. > > > > I downloaded the image from here > > < > > > https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/VNP46A3/ > > > > > (LAADS-DAAC, Level-1 and Atmosphere Archive & Distribution System > > Distributed Active Archive Center). The code I used to extract the NTL > > radiance image is: > > > > library(terra) > > > > wd <- "path/" > > > > r <- rast(paste0(wd, "VNP46A3.A2018091.h25v07.001.2021125122857.h5")) > > crs(r) <- "epsg:4326" > > > > 2400*(15/(60*60)) > > > > h = 25 > > v = 7 > > > > ext(r) = c(-180+h*10,-180+(h+1)*10, (v-2)*10,(v-1)*10) > > > > ntl <- r[[5]] > > > > writeRaster(ntl, paste0(wd, "ntl.tif"), overwrite = TRUE) > > > > Why the code worked perfectly in the previous question and now it > doesn't? > > From here > > < > https://drive.google.com/drive/folders/1V115zpdU2-5fXssI6iWv_F6aNu4E5qA7> > > you can download the .h5 image if you don't want to use NASA's website. I > > am using R 4.3.1 and RStudio 2023.06.2+561. > > > > -- > > Tziokas Nikolaos > > Cartographer > > > > Tel:(+44)07561120302 > > LinkedIn <http://linkedin.com/in/nikolaos-tziokas-896081130> > > > > [[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 > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo