Just did a test using GDAL 1.10.0 on Windows XP. It looks like ogr2ogr is now giving the correct results with both +no_uoff and +no_off.
Now we'll wait for QGIS to pick up the new GDAL. On Mon, Apr 29, 2013 at 12:05 AM, Andre Joost <[email protected]>wrote: > Am 28.04.2013 07:21, schrieb Hilmy Hashim: > >> Hello all, >> >> >> This query is about a discrepancy between projection results using the >> *Custom >> CRS Test* and *on-the-fly* transformation, and not about RSO per se. >> >> >> >> The Proj4 parameters for GDM2000 / Peninsula RSO (EPSG:3375) as given by >> epsg_tr.py (GDAL 1.9.2) are: >> >> +proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984 >> +x_0=804671 +y_0=0 +gamma=323.1301023611111 +ellps=GRS80 +units=m +no_defs >> >> This Malaysian projection requires the +no_off or *+no_uoff* flag (both >> >> works) for rotation at the natural origin as of proj 4.8. To test, I >> created a custom CRS based on GDM2000 / Peninsula RSO adding this flag. >> However, there seems to be some discrepancy between the on-the-fly derived >> results and the Test in the Custom CRS definition dialog. >> >> >> I set the project CRS as the custom CRS I created and added the test point >> in WGS84. >> >> Test points: *1.827764875* deg N, *103.640259872222* deg E (WGS84 >> EPSG:4326) >> >> Expected results: Northing *202,122.062* m, Easting *627,096.132* m >> (EPSG:3375) >> >> *The test points and projected coordinates are taken from the GDM2000 >> >> Technical Manual published by the Department of Survey and Mapping >> Malaysia. >> * >> >> *Test results (standard EPSG:3375)*: >> >> >> cs2cs — -240332.04, 958936.71 >> >> QGIS Master (13d35ac) On-the-fly derived: Y = -240,332.0326, X = >> 958,936.7057 >> >> QGIS Master (13d35ac) Custom CRS Test:* -240,332.0326* N, *958,936.7057* E >> >> >> QGIS 1.8 On-the-fly: projected coordinates not derived >> >> QGIS 1.8 Custom CRS Test: -240,332.0326 N, 958,936.7057 E >> >> *Test results (with +no_off flag)*: >> >> cs2cs — 202122.06, 627096.13 >> >> QGIS Master (13d35ac) On-the-fly derived: Y =* -240,332.0326*, X = * >> 958,936.7057* >> >> QGIS Master (13d35ac) Custom CRS Test: *202,122.0625* N, *627,096.1317* E >> >> >> QGIS 1.8 On-the-fly: projected coordinates not derived >> >> QGIS 1.8 Custom CRS Test: 202,122.0625 N, 627,096.1317 E >> >> >> It looks like the Custom CRS Definition Test dialog is giving the correct >> result, but the on-the-fly transformation is ignoring the +no_off flag. >> >> >> Is the on-the-fly transformation using a different transformation process >> and reading the proj4 parameters differently, or am I going about this >> wrongly? >> > > I made some tests with the similar Michigan omerc projections and ran into > the same problem: > http://trac.osgeo.org/gdal/**ticket/4910<http://trac.osgeo.org/gdal/ticket/4910> > > It looks like it is a GDAL problem. > > HTH, > André Joost > > ______________________________**_________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/**mailman/listinfo/qgis-**developer<http://lists.osgeo.org/mailman/listinfo/qgis-developer> >
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