One notably huge difference is that there is a huge jump in pixel size (from 0.000833333333323 to 205.686440189378940)...
ah, duh. Unit change. On Thu, Jun 11, 2015 at 2:26 PM, Ari Simmons <[email protected]> wrote: > I am experimenting with using 'gdalwarp' on a .vrt (first time), but I'm > not sure what I'm doing wrong. I've been running this: > > >> gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3857 -r bilinear -of VRT > merged.vrt srtm_merged_3857.vrt > > and it processes fast (far far *too fast* for this global file) and returns > > >> Creating output file that is 194835P X 479814L. > >> Processing input file merged.vrt > >> Using internal nodata values (eg. 0) for image merged.vrt > > The return .vrt file definitely doesn't appear right...a quick look at the > returned file: > > input: > > Size is 432000, 208800 > Coordinate System is: > GEOGCS["WGS 84", > DATUM["WGS_1984", > SPHEROID["WGS 84",6378137,298.257223563, > AUTHORITY["EPSG","7030"]], > AUTHORITY["EPSG","6326"]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433], > AUTHORITY["EPSG","4326"]] > Origin = (-180.000416666666670,84.000416666666666) > Pixel Size = (0.000833333333323,-0.000833333333323) > Corner Coordinates: > Upper Left (-180.0004167, 84.0004167) (180d 0' 1.50"W, 84d 0' 1.50"N) > Lower Left (-180.0004167, -89.9995833) (180d 0' 1.50"W, 89d59'58.50"S) > Upper Right ( 179.9995833, 84.0004167) (179d59'58.50"E, 84d 0' 1.50"N) > Lower Right ( 179.9995833, -89.9995833) (179d59'58.50"E, 89d59'58.50"S) > Center ( -0.0004167, -2.9995833) ( 0d 0' 1.50"W, 2d59'58.50"S) > Band 1 Block=128x128 Type=Int16, ColorInterp=Gray > NoData Value=0 > Overviews: 216000x104400, 108000x52200, 54000x26100, 27000x13050, > 13500x6525, > 6750x3263, 3375x1632, 1688x816, 844x408, 422x204 > > and output file: > > Size is 193861, > 479814 Coordinate > System is: > PROJCS["WGS 84 / > Pseudo-Mercator", > GEOGCS["WGS > 84", > DATUM["WGS_1984", > SPHEROID["WGS > 84",6378137,298.257223563, > AUTHORITY["EPSG","7030"]], > AUTHORITY["EPSG","6326"]], > PRIMEM["Greenwich",0, > AUTHORITY["EPSG","8901"]], > UNIT["degree",0.0174532925199433, > AUTHORITY["EPSG","9122"]], > AUTHORITY["EPSG","4326"]], > PROJECTION["Mercator_1SP"], > PARAMETER["central_meridian",0], > PARAMETER["scale_factor",1], > PARAMETER["false_easting",0], > PARAMETER["false_northing",0], > UNIT["metre",1, > AUTHORITY["EPSG","9001"]], > AXIS["X",EAST], > AXIS["Y",NORTH], > EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 > +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext > +no_defs"], > AUTHORITY["EPSG","3857"]] > Origin = > (-19837179.642485119000000,18807657.848855246000000) > Pixel Size = > (205.686440189378940,-205.686440189378940) Corner > Coordinates: > Upper Left (-19837179.642,18807657.849) (178d12' 1.50"W, 84d 0' > 1.50"N) Lower Left (-19837179.642,-79883575.764) (178d12' 1.50"W, > 89d59'58.50"S) Upper Right (20037399.339,18807657.849) > (179d59'56.47"E, 84d 0' 1.50"N) Lower Right > (20037399.339,-79883575.764) (179d59'56.47"E, 89d59'58.50"S) > Center ( 100109.848,-30537958.958) ( 0d53'57.49"E, 89d > 2'43.78"S) Band 1 Block=512x128 Type=Int16, > ColorInterp=Gray Overviews: 96931x239907, > 48466x119954, 24233x59977, 12117x29989, 6059x14995, 3030x7498, 1515x3749, > 758x1875, 379x938, 191x471 > > One notably huge difference is that there is a huge jump in pixel size > (from 0.000833333333323 to 205.686440189378940)... >
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