Method: PROJ#inverse

Defined in:
ext/rb_proj.c

#inverse(x1, y1, z1 = nil) ⇒ Object Also known as: inverse_lonlat

Transforms coordinates inversely from (x1, y1, z1) to (lon2, lat2, z2). The order of output coordinates is longitude, latitude and height. If the input coordinates are angles, they are treated as being in units ‘degrees`. The returned longitude and latitude are in units ’degrees’.

Examples:

lon2, lat2 = pj.inverse(x1, y1)
lon2, lat2, z2 = pj.inverse(x1, y1, z1)

Parameters:

  • x1 (Numeric)
  • y1 (Numeric)
  • z1 (Numeric, nil) (defaults to: nil)

Returns:

  • lon2, lat2, [, z2]



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# File 'ext/rb_proj.c', line 483

static VALUE
rb_proj_inverse (int argc, VALUE *argv, VALUE self)
{
  volatile VALUE vx, vy, vz;
  Proj *proj;
  PJ_COORD data_in, data_out;
  int errno;

  rb_scan_args(argc, argv, "21", (VALUE *)&vx, (VALUE *)&vy, (VALUE *)&vz);
  Data_Get_Struct(self, Proj, proj);

  if ( ! proj->is_src_latlong ) {
    rb_raise(rb_eRuntimeError, "requires latlong src crs. use #transform_inverse instead of #inverse.");
  }

  if ( proj_angular_input(proj->ref, PJ_INV) == 1 ) {
    data_in.lpz.lam = proj_torad(NUM2DBL(vx));
    data_in.lpz.phi = proj_torad(NUM2DBL(vy));
    data_in.lpz.z   = NIL_P(vz) ? 0.0 : NUM2DBL(vz);
  }
  else {
    data_in.xyz.x = NUM2DBL(vx);
    data_in.xyz.y = NUM2DBL(vy);
    data_in.xyz.z = NIL_P(vz) ? 0.0 : NUM2DBL(vz);
  }

  data_out = proj_trans(proj->ref, PJ_INV, data_in);

  if ( data_out.lpz.lam == HUGE_VAL ) {
    errno = proj_errno(proj->ref);
    rb_raise(rb_eRuntimeError, "%s", proj_errno_string(errno));
  }

  if (  proj_angular_output(proj->ref, PJ_INV) == 1 ) {    
    if ( NIL_P(vz) ) {
      return rb_assoc_new(rb_float_new(proj_todeg(data_out.lpz.lam)), 
                          rb_float_new(proj_todeg(data_out.lpz.phi)));
    } else {
      return rb_ary_new3(3, rb_float_new(proj_todeg(data_out.lpz.lam)), 
                            rb_float_new(proj_todeg(data_out.lpz.phi)),
                            rb_float_new(data_out.lpz.z));
    }
  }
  else {
    if ( NIL_P(vz) ) {
      return rb_assoc_new(rb_float_new(data_out.xyz.x), 
                          rb_float_new(data_out.xyz.y));
    } else {
      return rb_ary_new3(3, rb_float_new(data_out.xyz.x), 
                            rb_float_new(data_out.xyz.y),
                            rb_float_new(data_out.xyz.z));
    }    
  }
}