On Wed, Mar 22, 2017 at 8:12 PM, Markus Neteler <[email protected]> wrote: > > On Sat, Mar 11, 2017 at 7:01 PM, Markus Metz > <[email protected]> wrote: > > On Sat, Mar 11, 2017 at 8:53 AM, Nikos Alexandris < [email protected]> > > wrote: > >> > >> Nikos Alexandris > >> > >>>> Why does (attempting to) import a 38m pixel resolution GHSL [0] GeoTIFF > >>>> layer, ie GHS_BUILT_LDS1990_GLOBE_R2016A_3857_38_v1_0_p1.tif, in GRASS' > >>>> db progress slow? > > > > because it is a very large raster map: Size is 507904, 647168 > > Nikos, for an even bigger map try > > Global Surface Water (2000-2012, 30 m, Data coverage is from 80° north > to 60° south): http://landcover.usgs.gov/glc/WaterDescriptionAndDownloads.php > by USGS. 1.6GB in size. > > Using gdalbuildvrt I created a VRT from the 504 GeoTIFF files. > > After import into GRASS GIS, here the timings: > > # final map size: > g.region -p > ... > rows: 493200 > cols: 1296001 > cells: 639187693200 > > (handling only works in GRASS GIS 7.3.svn since Markus Metz's recent > improvements on global data import are needed).
(my changes were bug fixes, not improvements) > > Benchmarks: > - Import took 2h while reading the data from a CIFS mounted storage > box (slow) and writing on SSD. > - Displaying the entire map (639 giga-pixel) in GRASS GIS' display > (d.mon) took ~15 sec over a ssh tunnel from my laptop to the server, > since I am at a conference. > > Fair deal I would say :-) A bit more information would help to compare: - what is your GDAL version? - are 504 GeoTIFF files compressed? If yes, which method? - what are the block dimensions of the input GeoTIFFs? - what kind of GRASS compression did you use? Markus M
_______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
