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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Frank, Even or whoever,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have a source geotiff that has the following projection:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN>PROJCS["State Plane",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS 1980",6378137,298.2572221010002,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4269"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["standard_parallel_1",35.46666666666667],PARAMETER["standard_parallel_2",34.03333333333333],PARAMETER["latitude_of_origin",33.5],PARAMETER["central_meridian",-118],PARAMETER["false_easting",21527734.72222222],PARAMETER["false_northing",5381933.680555555],UNIT["feet",0.3048006096012192],AUTHORITY["EPSG","26945"]]<o:p></o:p></span></p><p class=MsoNormal><span lang=EN><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'>I want to convert the bounds to WGS84. When I setup my coordinate transform object the <span style='font-size:9.5pt;font-family:Consolas'>OGRProj4CT::InitializeNoLock() function in ogrct.cpp calls poSRSSource->exportToProj4() and returns the following:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>+proj=lcc +lat_1=35.46666666666667 +lat_2=34.03333333333333 +lat_0=33.5 +lon_0=-118 +x_0=6561666.666666666 +y_0=1640416.666666667 +datum=NAD83 +units=us-ft +no_defs<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>Then, when calling TransformEx() on the bounds the resulting coordinates are wrong. It appears that somewhere in the transformation process the UNIT RADIANS value is not being factored correctly with the false eating and northing values.<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>If I translate the source image into a new geotiff with the exact same parameters as the source geotiff then the new projection is as follows:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>PROJCS["NAD83 / California zone 5",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS 1980",6378137,298.2572221010002,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4269"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["standard_parallel_1",35.46666666666667],PARAMETER["standard_parallel_2",34.03333333333333],PARAMETER["latitude_of_origin",33.5],PARAMETER["central_meridian",-118],PARAMETER["false_easting",6561666.666666666],PARAMETER["false_northing",1640416.666666667],UNIT["US survey foot",0.3048006096012192,AUTHORITY["EPSG","9003"]],AUTHORITY["EPSG","26945"]]<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>And the </span><span style='font-size:9.5pt;font-family:Consolas'>exportToProj4() returns this:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>+proj=lcc +lat_1=35.46666666666667 +lat_2=34.03333333333333 +lat_0=33.5 +lon_0=-118 +x_0=2000000 +y_0=500000.0000000001 +datum=NAD83 +units=us-ft +no_defs<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>Which produces a correct result when using TransformEx().<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span lang=EN>When I get the </span><span style='font-size:9.5pt;font-family:Consolas'>SRS_PP_FALSE_EASTING and SRS_PP_FALSE_NORTHING from both projections using the OGRSpatialReference::GetProjParm() function I notice the difference between the two is a factor of the GEOGCS unit radians:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>SOURCE IMAGE:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>false_easting: 21527734.72222<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>false_northing: 5381933.680556<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>TRANSLATED IMAGE:<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>false_easting: 6561666.666667<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>false_northing: 1640416.666667<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>The translated offsets divided by the source offsets seem to be a factor of the unit radians: 0.3048 <o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>I think the reason that the translate to geotiff corrects the problem is that the geotiff keys for the projection are calculated in a different manner than when using the OGRCoordinateTransform object.<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>Any help on where to apply the fix in the GDAL code if you think one is required would be much appreciated. If you think I need to accommodate this in my code any help would be greatly appreciated.<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>Best regards,<o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>Martin<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>