public double degBetween(OrderedTriple t) {
return Rotater.rad2Deg(radBetween(t));
}
private void extractProjection() throws TransformationException {
Projection proj = null;
Scaler ncpScale = null;
String lonType = h.getStringValue("CTYPE" + lonAxis).substring(5, 8);
String latType = h.getStringValue("CTYPE" + latAxis).substring(5, 8);
if (!lonType.equals(latType)) {
throw new TransformationException(
"Inconsistent projection in FITS header: " + lonType + "," + latType);
}
if (lonType.equals("AIT")) {
proj = new Projection("Ait");
} else if (lonType.equals("CAR")) {
proj = new Projection("Car");
// Allow non-central latitudes for the Cartesian projection.
try {
double lon = h.getDoubleValue("CRVAL" + lonAxis);
if (lon != 0) {
proj.setReference(toRadians(lon), 0);
}
} catch (Exception e) {
System.err.println("Unable to read reference longitude in Cartesian projection");
}
} else if (lonType.equals("CSC")) {
proj = new Projection("Csc");
} else if (lonType.equals("SFL") || lonType.equals("GLS")) {
proj = new Projection("Sfl");
} else if (lonType.equals("TOA")) {
proj = new Projection("Toa");
} else {
double crval1 = h.getDoubleValue("CRVAL" + lonAxis, NaN);
double crval2 = h.getDoubleValue("CRVAL" + latAxis, NaN);
if (isNaN(crval1 + crval2)) {
throw new TransformationException("Unable to find reference coordinates in FITS header");
}
wcsKeys.put("CRVAL1", crval1);
wcsKeys.put("CRVAL2", crval2);
if (lonType.equals("TAN")
|| lonType.equals("SIN")
|| lonType.equals("ZEA")
|| lonType.equals("ARC")
|| lonType.equals("STG")) {
String type = lonType.substring(0, 1) + lonType.substring(1, 3).toLowerCase();
proj = new Projection(type, new double[] {toRadians(crval1), toRadians(crval2)});
double lonpole = h.getDoubleValue("LONPOLE", NaN);
if (!isNaN(lonpole)) {
wcsKeys.put("LONPOLE", lonpole);
}
// ---- Following is probably erroneous -----
// The WCS standard indicates that the default LONPOLE for
// a projection is 180 when the CRVAL latitude is less than
// the native latitude of the projection (90 degrees for the projections
// handled here) and 0 otherwise. This means that for a projection
// around the pole the default lonpole is 0. Some data (the SFD surveys)
// seem to require that we do a rotation of 180 degrees to accommodate
// this. However we do not implement this unless the LONPOLE is
// explicitly given since this seems non-intuitive to me and I suspect
// that a user who is not careful enough to specify a LONPOLE in this
// situation probably doesn't understand what is going on anyway.
// ----- We now assume that our standard processing of
// ----- zenithal projections handles lonpole of 180 and that
// ----- this is the default for all zenithal images.
// ----- Previously we assumed that we were using lonPole=0 at
// ----- at the poles, but we weren't....
//
if (!isNaN(lonpole)) {
double lonDefault = 180;
if (lonpole != lonDefault) {
Rotater r = proj.getRotater();
Rotater lon = new Rotater("Z", toRadians(lonpole - lonDefault), 0, 0);
if (r != null) {
proj.setRotater(r.add(lon));
} else {
proj.setRotater(lon);
}
}
}
} else if (lonType.equals("NCP")) {
// Sin projection with projection centered at pole.
double[] xproj = new double[] {toRadians(crval1), PI / 2};
if (crval2 < 0) {
xproj[1] = -xproj[1];
}
double poleOffset = sin(xproj[1] - toRadians(crval2));
// Have we handled South pole here?
proj = new Projection("Sin", xproj);
// NCP scales the Y-axis to accommodate the distortion of the SIN projection away
// from the pole.
ncpScale = new Scaler(0, poleOffset, 1, 0, 0, 1);
ncpScale = ncpScale.add(new Scaler(0., 0., 1, 0, 0, 1 / sin(toRadians(crval2))));
} else {
throw new TransformationException("Unsupported projection type:" + lonType);
}
}
this.proj = proj;
if (ncpScale != null) {
this.scale = ncpScale;
}
add(proj.getRotater());
add(proj.getProjecter());
add(ncpScale); // Ignored if null
}
