[Proj] proj/libgeotiff interaction: GTIFProj4ToLatLong()

Eric Miller EMiller at dfg.ca.gov
Thu Mar 9 14:40:46 EST 2006

You don't show how the variable "proj_is_latlong" is defined or assigned to.  If it's zero, GTIFProj4ToLatLong will not be called.  Also, if GTIFProj4ToLatLong returns zero for success (a typical return code) then your error message will print.

>>> "Curt, WE7U" <archer at eskimo.com> 3/9/2006 10:58 AM >>>

This has to do with an interaction between proj and libgeotiff, so I
don't know which list to put it to, but since it has to do with a
proj function, I'll try here.

First, the code:

  if (GTIFGetDefn (gtif, &defn)) {
    if (debug_level & 16)
      GTIFPrintDefn (&defn, stdout);
  if ( proj_is_latlong || GTIFProj4ToLatLong( &defn, 1, &xxx, &yyy ) )   // Do all 4 of these in one call?
    if (debug_level & 16) {
      fprintf(stderr,"  (%s,", GTIFDecToDMS( xxx, "Long", 2 ) );
      fprintf(stderr,"%s)\n", GTIFDecToDMS( yyy, "Lat", 2) );
      fprintf(stderr,"%f  %f\n", xxx, yyy);
  else {
    fprintf(stderr,"Failed GTIFProj4ToLatLong() call\n");

I'm getting the "Failed GTIFProj4ToLatLong() call" message four
times, once for each such call I make.

I'm using these packages:


I verified by re-installing these just now that I installed proj
first, then installed libgeotiff, and the libgeotiff configure found
libproj just fine.

The geotiff I'm having a problem with has UTM zone 10 coordinates.
USGS DRG geoTIFF topo maps with Lat/Long coordinates (but UTM
projection) are read in just fine by my code.

Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer 
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"
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