We recently needed to add a custom SRS for GDA2020 / Australian Albers. We did this successfully by creating the user_projections folder and epsg.properties file and adding the Geoserver one line definition from https://epsg.io/9473
Since then, GWC started failing for layers using Google Global Mercator (EPSG:900913). The behaviour was that no new tiles were generated on disc when interacting with cached layers at new zoom levels (no errors in logs). Seeding the cache also created no new tiles and this was the only error in the logs.
ERROR [seed.MTSeeder] - Problem communicating with GeoServer
org.geowebcache.GeoWebCacheException: Problem communicating with GeoServer
We realised 900913 had disappeared from Geoserver’s known SRS list since adding the custom SRS. Other common SRS such as EPSG:4326 that we also use for GWC continue to work fine.
We then added EPSG:900913 as an additional custom definition to the epsg.properties file, using the one-line Geoserver definition from https://epsg.io/900913. Google Global Mercator was again available from the SRS list and could be used GWC seeding as usual. We confirmed that new tiles were again being created on disc in the GWC directory. However, this custom defined 900913 SRS appears to be ‘shifted’ by approximately 15km due north (at -22 latitude), but only for tiles rendered by GWC. Any layers served out via WMS in 900913 without tile caching switched on are rendered fine, after the addition of the custom 900913 definition.
GWC is using the inbuilt gridset for 900913 (which has previously worked fine).
This is the exact contents of our epsg.properties file:
900913=PROJCS[“Google_Maps_Global_Mercator”,GEOGCS[“WGS 84”,DATUM[“WGS_1984”,SPHEROID[“WGS 84”,6378137,298.257223563]],PRIMEM[“Greenwich”,0,AUTHORITY[“EPSG”,“8901”]],UNIT[“degree”,0.0174532925199433,AUTHORITY[“EPSG”,“9122”]],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”]],AXIS[“Easting”,EAST],AXIS[“Northing”,NORTH],EXTENSION[“PROJ4”,“+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@anonymised.com +wktext +no_defs”],AUTHORITY[“EPSG”,“900913”]]
9473=PROJCS[“GDA2020 / Australian Albers”,GEOGCS[“GDA2020”,DATUM[“Geocentric_Datum_of_Australia_2020”,SPHEROID[“GRS 1980”,6378137,298.257222101],TOWGS84[0,0,0,0,0,0,0]],PRIMEM[“Greenwich”,0,AUTHORITY[“EPSG”,“8901”]],UNIT[“degree”,0.0174532925199433,AUTHORITY[“EPSG”,“9122”]],AUTHORITY[“EPSG”,“7844”]],PROJECTION[“Albers_Conic_Equal_Area”],PARAMETER[“latitude_of_center”,0],PARAMETER[“longitude_of_center”,132],PARAMETER[“standard_parallel_1”,-18],PARAMETER[“standard_parallel_2”,-36],PARAMETER[“false_easting”,0],PARAMETER[“false_northing”,0],UNIT[“metre”,1,AUTHORITY[“EPSG”,“9001”]],AXIS[“Easting”,EAST],AXIS[“Northing”,NORTH],AUTHORITY[“EPSG”,“9473”]]
Specific Qs:
Why has adding the custom SRS for GDA2020 caused Google Mercator to disappear from the SRS list? Have we missed any steps or defined this incorrectly? Is this a bug?
Why has re-adding Google Mercator as a custom SRS worked fine for WMS, but GWC now has a ‘shifted’ projection issue? Have we defined this incorrectly?
Is anyone successfully using both 9437 and 900913 with GWC?
This is the first custom SRS we’ve defined so I’m not sure whether the same disappearing Google Mercator issue would occur with an alternate SRS.
We’re running Geoserver version 2.24.0
Thanks in advance for your help, this one has me stumped!
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