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I have data in a postgresql data store in EPSG:2163 and am displaying that using OpenLayers in EPSG:3857. This results in a ~25 km northerly shift when displayed either in QGIS or OpenLayers.

To test the reprojection I used GDAL and the Geoserver reprojection console, which confirmed that the x-coordinates were reprojecting correctly but the y-coordinates were artificially high.

GDAL: gdaltransform -s_srs EPSG:2163 -t_srs EPSG:3857 1494718.24465831 -1025289.47657808

output = -9310869.18028598 4090931.77295946 0 (this displays correctly).

Geoserver: Reprojection Console

output =-9310869.180285975 4115158.942481106 (this displays north of expected).

Resulting in a difference of 24.2 km.

It seems to me that this a projection problem within Geoserver, any ideas what the problem is or how I can get around this? If I reproject my source data in postgresql to EPSG:3857, there are no projection problems but I want to keep my source data in EPSG:2163.

  • I noticed that there is a difference in the coordinate system definition for EPSG:3857 between GDAL and Geoserver. GS = UNIT["degree", 0.017453292519943295] and GDAL = UNIT["degree",0.0174532925199433, though it seems like a very slight rounding difference. – akthor Apr 19 '14 at 17:24
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An offset of about 20 km to the North is usual between the ellipsoidal and the special Google spherical version of Mercator. I guess that recent versions of GDAL do it right.

Feel free to make a bug report at Geoserver.

In the meantime, avoid EPSG:3857 if possible, or do the reprojection inside Postgis or GDAL.

  • Thanks, I ended up creating views for my layers in postgres and reprojecting the geometry column to 3857. Then I publish the view instead of the table. Something like this:CREATE OR REPLACE VIEW [VIEW_NAME] AS SELECT st_transform(geometry, 3857) AS geometry, [FIELD_1], [FIELD_N] FROM [TABLE_NAME]; – akthor Apr 20 '14 at 19:57

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