I am writing an application that generates GeoTIFF files and trying to use ENVI 4.5 to validate them. I am seeing a strange conversion from UTM co-ordinates to lat/lon when the GeoTIFF has a custom defined ellipsoid and projection. As a test, I set the ellipsoid and Traverse Mercator values to be equal to UTM Zone 22S and WGS-84 and saved one GeoTIFF specifying a custom CS and one GeoTIFF using the named projected CS type. The GeoTIFF fields, as far as my limited understanding goes, appear to be correct in both files. Further, in OpenEV, the pixel to lat/lon conversion agrees for both images, but in ENVI I get different lat/long values out when using the GeoTIFF that has a custom defined co-ordinate system. The fact that OpenEV handles customCRS.tif correctly, leads me to believe that the GeoTIFF files are okay. I have attached both GeoTIFF test images and included the disagreeing output in the cursor information window. The output from listgeo is also included below for the two GeoTIFF files. As can be seen, the map co-ordinates agree, but the conversion to lat/lon yield different results. OpenEV and online UTM to lat/lon converters agree with ENVI for definedCrs.tif I anyone has any insight, it would be greatly appreciated. I am also curious whether later versions of ENVI show the same behaviour. Our end customer will be running ENVI 4.8, but I only have 4.5 available to test with at this time. If anyone has later versions of ENVI and could try to two attached GeoTIFF files and let me know the results, that would be greatly appreciated. Hopefully I am just doing something wrong with my GeoTIFF file. Thanks! Mike Attachment with GeoTIFF Files: geotiffs.zip I'm not sure if I attached this correctly or not. Let me know if it can't be downloaded. ENVI Cursor Information for definedCRS.tif Disp #1 (1,1) Scrn: R:73 G:73 B:73 Projection: UTM, Zone 22 South Map: 517135.50E,9962917.50S Meters LL : 0.335496S, 50.846005W Data: 5 ENVI Cursor Information for customCRS.tif Disp #2 (1,1) Scrn: R:73 G:73 B:73 Projection: GEOTIFF (Transverse Mercator) Map: 517135.50E,9962917.50N Meters LL : 0.333997S, 50.846005W Data: 5 GeoTIFF Fields for definedCRS.tif Geotiff_Information: Version: 1 Key_Revision: 1.2 Tagged_Information: ModelTiepointTag (2,3): 0 0 0 517135.5 9962917.5 0 ModelPixelScaleTag (1,3): 1.5 1.5 0 End_Of_Tags. Keyed_Information: GTModelTypeGeoKey (Short,1): ModelTypeProjected GTRasterTypeGeoKey (Short,1): RasterPixelIsArea ProjectedCSTypeGeoKey (Short,1): PCS_WGS84_UTM_zone_22S End_Of_Keys. End_Of_Geotiff. PCS = 32722 (name unknown) Projection = 16122 () Projection Method: CT_TransverseMercator ProjNatOriginLatGeoKey: 0.000000 ( 0d 0' 0.00"N) ProjNatOriginLongGeoKey: -51.000000 ( 51d 0' 0.00"W) ProjScaleAtNatOriginGeoKey: 0.999600 ProjFalseEastingGeoKey: 500000.000000 m ProjFalseNorthingGeoKey: 10000000.000000 m GCS: 4326/WGS 84 Datum: 6326/World Geodetic System 1984 Ellipsoid: 7030/WGS 84 (6378137.00,6356752.31) Prime Meridian: 8901/Greenwich (0.000000/ 0d 0' 0.00"E) Corner Coordinates: Upper Left ( 517135.500, 9962917.500) Lower Left ( 517135.500, 9962217.000) Upper Right ( 517821.000, 9962917.500) Lower Right ( 517821.000, 9962217.000) Center ( 517478.250, 9962567.250) GeoTIFF Fields for customCRS.tif Geotiff_Information: Version: 1 Key_Revision: 1.2 Tagged_Information: ModelTiepointTag (2,3): 0 0 0 517135.5 9962917.5 0 ModelPixelScaleTag (1,3): 1.5 1.5 0 End_Of_Tags. Keyed_Information: GTModelTypeGeoKey (Short,1): ModelTypeProjected GTRasterTypeGeoKey (Short,1): RasterPixelIsArea GeographicTypeGeoKey (Short,1): User-Defined GeogCitationGeoKey (Ascii,7): "WGS 84" GeogGeodeticDatumGeoKey (Short,1): User-Defined GeogPrimeMeridianGeoKey (Short,1): User-Defined GeogAngularUnitsGeoKey (Short,1): User-Defined GeogAngularUnitSizeGeoKey (Double,1): 0.0174532925 GeogEllipsoidGeoKey (Short,1): User-Defined GeogSemiMajorAxisGeoKey (Double,1): 6378137 GeogInvFlatteningGeoKey (Double,1): 298.257224 GeogPrimeMeridianLongGeoKey (Double,1): 0 ProjectedCSTypeGeoKey (Short,1): User-Defined PCSCitationGeoKey (Ascii,22): "WGS 84 / UTM zone 22S" ProjectionGeoKey (Short,1): User-Defined ProjCoordTransGeoKey (Short,1): CT_TransverseMercator ProjLinearUnitsGeoKey (Short,1): Linear_Meter ProjLinearUnitSizeGeoKey (Double,1): 1 ProjNatOriginLongGeoKey (Double,1): -51 ProjNatOriginLatGeoKey (Double,1): 0 ProjFalseEastingGeoKey (Double,1): 500000 ProjFalseNorthingGeoKey (Double,1): 10000000 ProjScaleAtNatOriginGeoKey (Double,1): 0.9996 End_Of_Keys. End_Of_Geotiff. Projection Method: CT_TransverseMercator ProjNatOriginLatGeoKey: 0.000000 ( 0d 0' 0.00"N) ProjNatOriginLongGeoKey: -51.000000 ( 51d 0' 0.00"W) ProjScaleAtNatOriginGeoKey: 0.999600 ProjFalseEastingGeoKey: 500000.000000 m ProjFalseNorthingGeoKey: 10000000.000000 m Projection Linear Units: 9001/metre (1.000000m) Corner Coordinates: Upper Left ( 517135.500, 9962917.500) Lower Left ( 517135.500, 9962217.000) Upper Right ( 517821.000, 9962917.500) Lower Right ( 517821.000, 9962217.000) Center ( 517478.250, 9962567.250)