I have a large number - more than 60 thousand - of relatively small Geotiffs, usually from 2 to 12 Mb. I am currently serving them using Geoserver, but things are quite slow even inside our own network. I have a hunch that both Geoserver and these Geotiffs are not configured in the best way possible.
Here is the output from gdalinfo for a typical one:
Driver: GTiff/GeoTIFF
Files: se502c_R9_C1_3_T_2531_sec.rsl.tif
Size is 3396, 2271
Coordinate System is:
PROJCS["ETRS89 / LAEA Europe",
GEOGCS["ETRS89",
DATUM["European_Terrestrial_Reference_System_1989",
SPHEROID["GRS 1980",6378137,298.2572221010002,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6258"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4258"]],
PROJECTION["Lambert_Azimuthal_Equal_Area"],
PARAMETER["latitude_of_center",52],
PARAMETER["longitude_of_center",10],
PARAMETER["false_easting",4321000],
PARAMETER["false_northing",3210000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","3035"]]
Origin = (4645325.000000000000000,3992425.000000000000000)
Pixel Size = (25.000000000000000,-25.000000000000000)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
COMPRESSION=DEFLATE
INTERLEAVE=BAND
Corner Coordinates:
Upper Left ( 4645325.000, 3992425.000) ( 15d37'30.88"E, 58d55' 2.56"N)
Lower Left ( 4645325.000, 3935650.000) ( 15d32'42.77"E, 58d24'30.92"N)
Upper Right ( 4730225.000, 3992425.000) ( 17d 5'21.12"E, 58d50'57.39"N)
Lower Right ( 4730225.000, 3935650.000) ( 16d59'19.12"E, 58d20'29.67"N)
Center ( 4687775.000, 3964037.500) ( 16d18'44.44"E, 58d37'52.11"N)
Band 1 Block=512x512 Type=Float32, ColorInterp=Gray
NoData Value=-9999
As you can see they are EPSG:3035. They should be internally tiled. In the Coordinate Reference Systems for Geoserver, it says that both Native SRSand Declared SRS are EPSG:3035, and that the handling should be to reproject native to declared.
My web client overlays these Geotiffs on a standard OpenStreetMap layer in Web Mercator. All the geotiffs we have tried appear correctly, so I guess reprojection is still happening at some stage.
Would I gain any speed changing the declared SRS to Web Mercator? Or reprojecting the original Geotiffs to Web Mercator? What other properties of the Geotiff could I tinker with?
Bonus question - if a Geotiff is changed, reprojecting or retiling or what have you, does the Geoserver layer associated with it also change automatically?