I am trying to display an existing GeoTIFF file (from the FAA WAC set) in an application that requires the GeoTIFF NaturalOriginLongitude tag (FalconView 5.1.1). There are some older files in that set that display OK, and newer files that don't appear.
I'm confident that it is that tag (from running the code in a debugger, and from trying "fake" longitude values in files). That is, I know how to add the tag (using listgeo and geotifcp) as described in an earlier question, and adding the tag makes the file appear.
However the values that I'm putting in aren't providing an appropriately georeferenced display. I've tried zero (because that seemed like something easy) and I've tried using the same value as is in FalseOriginLongitude (which is what the older files seemed to contain). Setting NaturalOriginalLongitude to be the same as the FalseOriginLongitude value is definitely better than setting it to zero, but its a little off in Longitude (a few minutes) and a lot off in Latitude (a few degrees).
I tried some likely-looking google hits (especially an EPSG Guidance Note 7 Part2), but I didn't find anything that gives me the natural origin longitude (lambda0) value that I need.
Here is the output of listgeo for a specific file that does not display.
$ listgeo CG-18\ WAC\ 42\ North.tif TIFFReadDirectory: Warning, CG-18 WAC 42 North.tif: unknown field with tag 42112 (0xa480) encountered. TIFFReadDirectory: Warning, CG-18 WAC 42 North.tif: unknown field with tag 42113 (0xa481) encountered. Geotiff_Information: Version: 1 Key_Revision: 1.0 Tagged_Information: ModelTiepointTag (2,3): 0 0 0 -833364.681326397491974.541710076 0 ModelPixelScaleTag (1,3): 126.87142 126.87142 0 End_Of_Tags. Keyed_Information: GTModelTypeGeoKey (Short,1): ModelTypeProjected GTRasterTypeGeoKey (Short,1): RasterPixelIsArea GTCitationGeoKey (Ascii,21): "PCS Name = CG-18 WAC" GeographicTypeGeoKey (Short,1): GCS_NAD83 GeogCitationGeoKey (Ascii,24): "GCS_North_American_1983" GeogAngularUnitsGeoKey (Short,1): Angular_Degree GeogSemiMajorAxisGeoKey (Double,1): 6378137 GeogInvFlatteningGeoKey (Double,1): 298.257222101 ProjectedCSTypeGeoKey (Short,1): User-Defined ProjectionGeoKey (Short,1): User-Defined ProjCoordTransGeoKey (Short,1): CT_LambertConfConic_2SP ProjLinearUnitsGeoKey (Short,1): Linear_Meter ProjStdParallel1GeoKey (Double,1): 38.66667 ProjStdParallel2GeoKey (Double,1): 33.33333 ProjFalseOriginLongGeoKey (Double,1): -118.085 ProjFalseOriginLatGeoKey (Double,1): 36 ProjFalseOriginEastingGeoKey (Double,1): 0 ProjFalseOriginNorthingGeoKey (Double,1): 0 End_Of_Keys. End_Of_Geotiff. Projection Method: CT_LambertConfConic_2SP ProjFalseOriginLatGeoKey: 36.000000 ( 36d 0' 0.00"N) ProjFalseOriginLongGeoKey: -118.085000 (118d 5' 6.00"W) ProjStdParallel1GeoKey: 38.666670 ( 38d40' 0.01"N) ProjStdParallel2GeoKey: 33.333330 ( 33d19'59.99"N) ProjFalseEastingGeoKey: 0.000000 m ProjFalseNorthingGeoKey: 0.000000 m GCS: 4269/NAD83 Datum: 6269/North American Datum 1983 Ellipsoid: 7019/GRS 1980 (6378137.00,6356752.31) Prime Meridian: 8901/Greenwich (0.000000/ 0d 0' 0.00"E) Projection Linear Units: 9001/metre (1.000000m) Corner Coordinates: Upper Left ( -833364.681, 491974.542) (127d51'15.84"W, 40d 3'23.84"N) Lower Left ( -833364.681, -31877.551) (127d16'36.93"W, 35d21'26.95"N) Upper Right ( 685286.216, 491974.542) (110d 2'34.02"W, 40d10'41.37"N) Lower Right ( 685286.216, -31877.551) (110d31' 8.78"W, 35d28'20.04"N) Center ( -74039.233, 230048.495) (118d55'44.97"W, 38d 4'18.53"N)
There are also world files for each TIFF. Here is an example:
$ cat CG-18\ WAC\ 42\ North.tfw 126.8714200000 0.0000000000 0.0000000000 -126.8714200000 -833301.2456163971 491911.1060000764
There are also HTML files providing metadata, but it seems (to me) to be a subset of the GeoTIFF tags.
Any suggestions for how to get a reasonable value for NaturalOriginLongitude from the information I have available?