I am trying to set up my osgearth dev environment on a new machine and was unable to use my existing earth file to populate a cache via osgearth_cache. I then tried it with the readymap.earth file packaged with the OSGEarth tests and I got the same error. What would cause a failure to create "tms" driver?
osgearth_cache.exe --seed MyPathToEarthFile\readymap.earth
[osgEarth] [TerrainLayer] Layer "readymap_elevation" Failed to create "tms" driver, but a cache may exist, so falling back on cache-only mode.
[osgEarth]* [EarthSerializer2] Layer "readymap_elevation" : Error : Failed to open a cache for layer because cache_only policy is in effect and bin [0122c14e] could not be located.
Usually this means that the TMS plugin (osgdb_osgearth_tms.dll or one of its dependencies) could not be found or loaded. Maybe there's a problem with your path? Or you have an old version somewhere? Sometimes a complete rebuild can help.