I am checking the conversion results against a file of the same data that my source provided after running the data through ArcGIS to convert it to geographic directly. I don't have access to ArcGIS, so I can't just do that. I need an in-house more direct tool to integrate with our system.
I am not a math major, just an old line programmer, so I can't easily understand why this is happening.
Anybody got an idea about how I might fix this?
Here is the metadata from the UTM file I am converting followed by some points and conversions. I have determined that for the initial points they are pretty much 6000 meters too far north. I can get them within ~100 meters if I subtract 5500 meters before converting, so that suggests, since it doesn't get precisely there if I subtract 'exactly' 6000 meters, that the calculations are still off somewhere in the math.
geogcsn Sync="TRUE" GCS_North_American_1983
projcsn Sync= "TRUE" NAD_1983_UTM_Zone_12N
UNIT ”Degree” 0.0174532925199433
PARAMETER ”False_Northing”,0.0 PARAMETER ”Central_Meridian”,-111.0 PARAMETER ”Scale_Factor”,0.9996 PARAMETER ”Latitude_Of_Origin”,0.0 UNIT ”Meter”,1.0 XOrigin -5120900 YOrigin -9998100 XYScale 450445547.3910538 ZOrigin 100000 ZScale 10000 MOrigin -100000 MScale 10000 XYTolerance 0.001 ZTolerance 0.001& MTolerance 0.001< HighPrecision true bounds minlat="4094776.60000000" minlon="228582.50000000" maxlat="4653399.00000000" maxlon="673947.300000007"
UTM CNV lat = 4650693.00000000 lon = 389280.60000000 lat = 42.04826024690 lon = -112.33814680302 lat = 4650348.50000000 lon = 389380.40000000 lat = 42.04517176050 lon = -112.33687612607 lat = 4650360.00000000 lon = 389520.70000000 lat = 42.04529498908 lon = -112.33518315671 lat = 4650690.50000000 lon = 389650.40000000 lat = 42.04828955593 lon = -112.33367812578 lat = 4650673.00000000 lon = 390428.00000000 lat = 42.04824036112 lon = -112.32427926799 lat = 4650328.50000000 lon = 390489.50000000 lat = 42.04514639600 lon = -112.32347200664
I did look at the Guidance 7-2 document that was suggested and I 'might' be able to convert the formulas to the scripting language, but it will probably cost me what little hair I have left on my head... the conversion from one language to another was relatively easy, but translating the formula direct may be above my rusted-out math skills. I will check with our forecaster, he may be able to help me.