Maciej, I am looking at equations 3.74 on page 25 (PDF page 31) of part one of the COSMO manual: http://www.cosmo-model.org/content/model/documentation/core/cosmoDyncsNumcs.pdf
I note that (lambda_g^N, phi_g^N) is the North Pole of the rotated grid, so phi_g^N is not latitudeOfOrigin, which is measured from the equator. According to the javadoc of MapProjection, points are adjusted for central_meridian but not latitude_of_origin: https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/main/java/org/geotools/referencing/operation/projection/MapProjection.java Kind regards, Ben. On 18/03/16 15:31, Ben Caradoc-Davies wrote: > Maciej, > > thank you for your contribution of the General Oblique Transform to > GeoTools. > https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/main/java/org/geotools/referencing/operation/projection/GeneralOblique.java > https://osgeo-org.atlassian.net/browse/GEOT-5190 > > While attempting use the General Oblique transform, I have encountered a > discrepancy between the latitude of the origin and the projected latitude. > > In the test script: > > https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/test/resources/org/geotools/referencing/test-data/scripts/GeneralOblique.txt > > The test General Oblique coordinate system is specified with: > > PARAMETER["central_meridian", 19.3], > PARAMETER["latitude_of_origin", 37.5] > > The following assertion is made: > > source pt = (0, 0) > target pt = (19.300000,52.500000) > > This looks wrong to me because I expected the origin of the rotated > coordinate system to have the latitude specified in the parameter > latitude_of_origin, that is 37.5. > > If I specify my own General_Oblique CRS in GeoServer with > PARAMETER["central_meridian", -106] and PARAMETER["latitude_of_origin", > 54] and use the reprojection console to reproject (0, 0) to WGS84, I get > the (lon, lat) = (-106.0, 36.0) which is incorrect. Likewise (-106.0, > 54.0) projected to this same General Oblique CRTS is incorrectly > projected to (0.0, 18.0) (should be (0,0)). > > In each case, it appears to me that the transformed latitude is 90 > degrees minus the expected latitude. This is consistent with the > latitude being measured from the North Pole not the equator. As this is > a common mathematical convention, I wonder if there is a problem with > the implementation of the General Oblique transformation. Can you see > anything wrong? Or do I misunderstand? > > If this is changed, we will need your help to generate and validate > changes to the test script. > > Kind regards, > -- Ben Caradoc-Davies <b...@transient.nz> Director Transient Software Limited <http://transient.nz/> New Zealand ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 _______________________________________________ GeoTools-Devel mailing list GeoTools-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
