On 16 August 2012 12:36, Craig Leat <[email protected]> wrote: > Nice work Grant! I found gaps too and most resulted from incorrect > georeferencing embedded in the sid or tif file. The world files were > correct, but gdal ignores them and gives precedence to the embedded > georeferencing. I had to create gdal vrt files and fill them with the > information from the world files. >
The method I ended up using was building gdal vrt files from the 9 zones. I then built external gdaladdo overviews. I then use mapserver to serve the 9 zones as layers with "OFFSITE 0 0 0" to turn pure black to transparent so that the zones overlap. Example commands: vrt build: gdalbuildvrt -resolution highest -overwrite central_meridian_33.vrt path/*.tif overviews: gdaladdo --config GDAL_CACHEMAX 1000 -ro --config COMPRESS_OVERVIEW JPEG --config JPEG_QUALITY_OVERVIEW 75 --config INTERLEAVE_OVERVIEW PIXEL --config PHOTOMETRIC YCBCR --config BIGTIFF_OVERVIEW YES --config GDAL_TIFF_OVR_BLOCKSIZE 512 -r gauss central_meridian_33.vrt 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 / Grant _______________________________________________ Talk-ZA mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-za
