[Geotiff] Conversion from lat/long to PCS to raster

[Fernando Cacciola]

Hi,

I plan to use libgeotiff (never used it beefore) to convert from
lat/long (GCS) to raster pixels.

IIIUC I need to convert lat/long to northings/eastings first (GCS ->
PCS), then PCS to Raster space.

I can see in libgeotiff the function GTIFPCSToImage, for PCS->Raster,
and I can also see a GTIFProj4FromLatLong(), which appears to be for
GCS to PCS, but I'm not sure how to use it.

Or rather, I can't get it to work: with a test geotiff I have,
lat/long and northings/eastings end up the same when I call
GTIFProj4FromLatLong (which of course won't give the correct raster
coordinates since this geotiff is ModelTypeProjected)

I called GTIFGetProj4Defn(&defn) FWIW.

Is this supported and I'm missing something? Or I cannot do this with
libgeotiff alone (and need GDAL instead)?

TIA

-- 
Fernando Cacciola
SciSoft Consulting, Founder
http://www.scisoft-consulting.com