I have a map image that I have reprojected from OSGB36 to googleMaps projection (EPSG:900913). When I run gdal2tiles on the reprojected map, the results are not alligned with the google maps images (its not just out by a little bit but by 10's of miles).
If I run it through MapTiler (from maptiler.org) it is aligned fine. MapTiler asks for an SRS which I dont specify when using gdal2tiles. So I'm thinking I've missied out a stage?
Also when I run gdalinfo on the warped file, the coords of the corners seem wrong. E.g. for the bottom-left corner the latitude is 51.143906, but it should be 50.955887 for google maps.
I'm usign gdal16 installed by OSGeo4W on Windows7 64-bit.
Warped file here.. https://docs.google.com/leaf?id=0B93lksnTC7_cNzIzZWQ0MDYtMTY5Yy00NjY0LThiMjktZjc2YzA3MmU5NjI4
gdalinfo on warped file...
C:\OSGeo4W\apps\gdal-16\bin>gdalinfo e:buckland_WARPED.tiff Driver: GTiff/GeoTIFF Files: e:buckland_WARPED.tiff Size is 611, 419 Coordinate System is: PROJCS["Google Maps Global Mercator", GEOGCS["WGS 84", DATUM["WGS_1984", SPHEROID["WGS 84",6378137,298.2572235630016, 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 = (-474051.292871501410000,6617009.987366309400000) Pixel Size = (8.392224865731517,-8.392224865731517) Metadata: AREA_OR_POINT=Area Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( -474051.293, 6617009.987) ( 4d15'30.51"W, 51d 9'49.57"N) Lower Left ( -474051.293, 6613493.645) ( 4d15'30.51"W, 51d 8'38.06"N) Upper Right ( -468923.643, 6617009.987) ( 4d12'44.69"W, 51d 9'49.57"N) Lower Right ( -468923.643, 6613493.645) ( 4d12'44.69"W, 51d 8'38.06"N) Center ( -471487.468, 6615251.816) ( 4d14'7.60"W, 51d 9'13.82"N) Band 1 Block=611x3 Type=Byte, ColorInterp=Red Mask Flags: PER_DATASET ALPHA Band 2 Block=611x3 Type=Byte, ColorInterp=Green Mask Flags: PER_DATASET ALPHA Band 3 Block=611x3 Type=Byte, ColorInterp=Blue Mask Flags: PER_DATASET ALPHA Band 4 Block=611x3 Type=Byte, ColorInterp=Alpha The sequence of commands I run are...
Georeference the OSGB PNG images...
gdal_translate -a_srs EPSG:27700 -gcp 0 400 241538.5 119812 -gcp 600 0 244713.5 121928.66666667 -gcp 0 0 241538.5 121928.66666667 -gcp 600 400 244713.5 11981 bucklands1.png bucklands1.tiff Warp into googleMaps projection (EPSG:900913) ...
gdalwarp -s_srs EPSG:27700 -t_srs EPSG:900913 -of GTiff bucklands1.tiff bucklands1_warped.tiff Tile (make into googleMap 256x256 tiles) ...
gdal2tiles bucklands1_warped.tiff gmTiles It works if I by-pass the gdalwarp stage and make google tiles directly from the OSGB36 images. But the image quality is poor as the interpolation is not so good.
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If I run it through MapTiler (from maptiler.org) it is aligned fine. MapTiler asks for an SRS which I dont specify when using gdal2tiles. So I'm thinking I've missied out a stage?
Also when I run gdalinfo on the warped file, the coords of the corners seem wrong. E.g. for the bottom-left corner the latitude is 51.143906, but it should be 50.955887 for google maps.
I'm usign gdal16 installed by OSGeo4W on Windows7 64-bit.
Warped file here.. https://docs.google.com/leaf?id=0B93lksnTC7_cNzIzZWQ0MDYtMTY5Yy00NjY0LThiMjktZjc2YzA3MmU5NjI4
gdalinfo on warped file...
C:\OSGeo4W\apps\gdal-16\bin>gdalinfo e:buckland_WARPED.tiff Driver: GTiff/GeoTIFF Files: e:buckland_WARPED.tiff Size is 611, 419 Coordinate System is: PROJCS["Google Maps Global Mercator", GEOGCS["WGS 84", DATUM["WGS_1984", SPHEROID["WGS 84",6378137,298.2572235630016, 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 = (-474051.292871501410000,6617009.987366309400000) Pixel Size = (8.392224865731517,-8.392224865731517) Metadata: AREA_OR_POINT=Area Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( -474051.293, 6617009.987) ( 4d15'30.51"W, 51d 9'49.57"N) Lower Left ( -474051.293, 6613493.645) ( 4d15'30.51"W, 51d 8'38.06"N) Upper Right ( -468923.643, 6617009.987) ( 4d12'44.69"W, 51d 9'49.57"N) Lower Right ( -468923.643, 6613493.645) ( 4d12'44.69"W, 51d 8'38.06"N) Center ( -471487.468, 6615251.816) ( 4d14'7.60"W, 51d 9'13.82"N) Band 1 Block=611x3 Type=Byte, ColorInterp=Red Mask Flags: PER_DATASET ALPHA Band 2 Block=611x3 Type=Byte, ColorInterp=Green Mask Flags: PER_DATASET ALPHA Band 3 Block=611x3 Type=Byte, ColorInterp=Blue Mask Flags: PER_DATASET ALPHA Band 4 Block=611x3 Type=Byte, ColorInterp=Alpha The sequence of commands I run are...
Georeference the OSGB PNG images...
gdal_translate -a_srs EPSG:27700 -gcp 0 400 241538.5 119812 -gcp 600 0 244713.5 121928.66666667 -gcp 0 0 241538.5 121928.66666667 -gcp 600 400 244713.5 11981 bucklands1.png bucklands1.tiff Warp into googleMaps projection (EPSG:900913) ...
gdalwarp -s_srs EPSG:27700 -t_srs EPSG:900913 -of GTiff bucklands1.tiff bucklands1_warped.tiff Tile (make into googleMap 256x256 tiles) ...
gdal2tiles bucklands1_warped.tiff gmTiles It works if I by-pass the gdalwarp stage and make google tiles directly from the OSGB36 images. But the image quality is poor as the interpolation is not so good.
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