[gdal-dev] map info and projections from GeoTIFF file to create ENVI header

[Nevzat Guler]

Dear experts,

I am reading LANDSAT GeoTIFF files and combining bands to create and ENVI
cube.
I am using GDAL to read the GeoTIFF file, and my own custom cube writer to
write the ENVI style cube. Transferring the map information proved to be a
bit convoluted. I seek your help to figure out this. 

My first problem is to access map info from GeoTIFF file. The map info
includes:

map info = {UTM, 1.000, 1.000, 145185.000, 2189715.000, 3.0000000000e+001,
3.0000000000e+001, 19, North, WGS-84, units=Meters}

I am able to get the location (x,y), and pixel size (x,y) from :
double adfGeoTransform[6];
srcDS->GetGeoTransform(adfGeoTransform);

But, I could not find any way to get the other variables in the string: UTM,
pixel tie points, Unit and DATUM. Is there any way to get them?

Finally, for the Coordinate System String, GDAL gives me:

PROJCS["unnamed",PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_or
igin
",0],PARAMETER["central_meridian",-69],PARAMETER["scale_factor",0.9996],PARA
METE
R["false_easting",500000],PARAMETER["false_northing",0],UNIT["Meter",1]]

But I should actually get

PROJCS["UTM_Zone_19N",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS
84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],A
UTHO
RITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["de
gree
",0.0174532925199433,AUTHORITY["EPSG","9108"]],AUTHORITY["EPSG","4326"]],PRO
JECT
ION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["cent
ral_
meridian",-69],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",50
0000
],PARAMETER["false_northing",0],UNIT["Meter",1]]

GDAL gives me PROJCS, "unnamed". And no GEOGCS information is given.  I am
able to get the coordinate system properties by using the following commands
but I first need to set few things to use exportToWTK.

>>       OGRSpatialReference oSRS;
>>       char *pszWKT = NULL;
>>       oSRS.SetProjCS("UTM_Zone_19N");
>>       oSRS.SetWellKnownGeogCS("WGS84");
>>       oSRS.SetUTM(19, TRUE);
>>       oSRS.SetWellKnownGeogCS("WGS84");
>>       oSRS.exportToWkt(&pszWKT);
>>       printf("%s\n", pszWKT);

However, this requires me to set SetProjCS, SetWellKnownGeogCS and SetUTM
first. I don't know these before I read the file. Is there any way to get
them from the file so that I don't need prior knowledge to create the
header. When I pull the GeoTIFF file into ENVI, all these information is
already there. If this list is only or development purposes, please let me
know if there is any other email list that can give me guidance on this
quest.

I appreciate your help and suggestions.
Best regards,
- Nevzat