I've downloaded 9 chunks of 1 arc-second NED in IMG format from the National Map. I'm trying to create a hillshade from them.
I'm using:
GDAL 1.10.0, released 2013/04/24First, I combine them and change the projection:
gdalwarp -t_srs EPSG:900913 n40w111/imgn40w111_1.img n40w112/imgn40w112_1.img \n40w113/imgn40w113_1.img n41w111/imgn41w111_1.img n41w112/imgn41w112_1.img \n41w113/imgn41w113_1.img n42w111/imgn42w111_1.img n42w112/imgn42w112_1.img \n42w113/imgn42w113_1.img uinta-projected.tifThen I create a hillshade from uinta-projected.tif:
gdaldem hillshade -compute_edges -co compress=lzw uinta-projected.tif uinta-hillshade.tifHowever, when I take a look at my shiny new hillshade, it looks like this:
Does anybody have any ideas what might be causing this grid artifact? I've tried using gdal_merge.py instead of gdalwarp and I end up with the same result.
gdalinfo uinta-projected.tif:
Driver: GTiff/GeoTIFFFiles: uinta-projected.tifSize is 9253, 12173Coordinate System is
ROJCS["Google Maps Global Mercator", 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"]], 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"]]]Origin = (-12579287.992128284648061,5161229.105774102732539)Pixel Size = (36.130094040215752,-36.130094040215752)Metadata: AREA_OR_POINT=AreaImage Structure Metadata: INTERLEAVE=BANDCorner Coordinates:Upper Left (-12579287.992, 5161229.106) (113d 0' 6.00"W, 42d11'34.83"N)Lower Left (-12579287.992, 4721417.471) (113d 0' 6.00"W, 39d11'11.36"N)Upper Right (-12244976.232, 5161229.106) (109d59'54.57"W, 42d11'34.83"N)Lower Right (-12244976.232, 4721417.471) (109d59'54.57"W, 39d11'11.36"N)Center (-12412132.112, 4941323.288) (111d30' 0.29"W, 40d42'24.63"N)Band 1 Block=9253x1 Type=Float32, ColorInterp=Gray
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I'm using:
GDAL 1.10.0, released 2013/04/24First, I combine them and change the projection:
gdalwarp -t_srs EPSG:900913 n40w111/imgn40w111_1.img n40w112/imgn40w112_1.img \n40w113/imgn40w113_1.img n41w111/imgn41w111_1.img n41w112/imgn41w112_1.img \n41w113/imgn41w113_1.img n42w111/imgn42w111_1.img n42w112/imgn42w112_1.img \n42w113/imgn42w113_1.img uinta-projected.tifThen I create a hillshade from uinta-projected.tif:
gdaldem hillshade -compute_edges -co compress=lzw uinta-projected.tif uinta-hillshade.tifHowever, when I take a look at my shiny new hillshade, it looks like this:
Does anybody have any ideas what might be causing this grid artifact? I've tried using gdal_merge.py instead of gdalwarp and I end up with the same result.
gdalinfo uinta-projected.tif:
Driver: GTiff/GeoTIFFFiles: uinta-projected.tifSize is 9253, 12173Coordinate System is
ROJCS["Google Maps Global Mercator", 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"]], 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"]]]Origin = (-12579287.992128284648061,5161229.105774102732539)Pixel Size = (36.130094040215752,-36.130094040215752)Metadata: AREA_OR_POINT=AreaImage Structure Metadata: INTERLEAVE=BANDCorner Coordinates:Upper Left (-12579287.992, 5161229.106) (113d 0' 6.00"W, 42d11'34.83"N)Lower Left (-12579287.992, 4721417.471) (113d 0' 6.00"W, 39d11'11.36"N)Upper Right (-12244976.232, 5161229.106) (109d59'54.57"W, 42d11'34.83"N)Lower Right (-12244976.232, 4721417.471) (109d59'54.57"W, 39d11'11.36"N)Center (-12412132.112, 4941323.288) (111d30' 0.29"W, 40d42'24.63"N)Band 1 Block=9253x1 Type=Float32, ColorInterp=Gray أكثر...