Nope, rebuilt netCDF but same timings.
-----Original Message----- From: gdal-dev <[email protected]> On Behalf Of Joaquim Manuel Freire Luís Sent: Friday, January 3, 2020 6:26 PM To: Jeff McKenna <[email protected]>; [email protected] Subject: Re: [gdal-dev] Slow GDALComputeRasterMinMax on nc grids Hi Jeff, Thanks for testing this. Sure it's useful. It also reminded me that I have a OSGeo4W with GDAL 2.4.1 but don't know which netCDF version, and using it took ... over 6 minutes. My Windows netCDF lib is a bit old by now (I build it from source). It might be it. Hi Joaquim, I have tested your file on Windows 10 here, with the command: gdalinfo grav_29_img.nc -mm which takes about 5 seconds to execute fully. I am using MS4W 4.0.2 (GDAL 2.4.3 , NetCDF 4.7.3 ) I haven't tested using your wrappers though, so imagine that my feedback is not very useful. PS. but thanks for sharing the larger grid file, which is useful for testing. Wishing you a prosperous 2020. -jeff -- Jeff McKenna MapServer Consulting and Training Services https://gatewaygeomatics.com/ On 2020-01-03 1:27 PM, Joaquim Manuel Freire Luís wrote: > Hi Even, > > New Year, new mysteries. I’m having quite strange slow times in > computing the min/max of netCDF files. > > In GMT we can read files via GDAL by appending =gd to the file name. > So both of these do a similar job > > grdinfo grav_29_img.nc=gd > > and > > gdalinfo grav_29_img.nc -mm > > and it takes around 28 sec in a new laptop running Windows and master > GDAL. However in WSL, same laptop but GDAL 2.2.3, they take about 5:30 > MINUTES to run. On a OSX it takes about 3:30 minutes (not me who run > this, and a GDAL 3.0.3 MacPorts) > > On Windows for files of similar size it run faster when data is of > type float (the grid in this example is a short int). > > Now, perhaps the weirdest thing is that if I run the GMT command via > our Julia wrapper it only takes ~8 sec, whilst the same command via > the Matlab wrapper took 1:18 min > > The ~8 sec time is close to what I get with a pure GMT (i.e. not using > GDAL to read the nc file (grdinfo grav_29_img.nc -M)) > > From the GMT side all happens in the call > > GDALComputeRasterMinMax(hBand, false, adfMinMax); > > And I guess that the same holds from the pure GDAL call. > > If you want to test with the grid used in these testings, it’s here > > ftp://ftp.soest.hawaii.edu > <ftp://ftp.soest.hawaii.edu.pwessel>/pwessel/grav_29_img.nc > <http://grav_29_img.nc> > > Happy new year > > Joaquim > > _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
