private void extractCoordinateSystem() throws TransformationException {
// To get the coordinate system we look at the CTYPEn, EQUINOX, RADESYSm
String lonType = h.getStringValue("CTYPE" + lonAxis).substring(0, 4);
String latType = h.getStringValue("CTYPE" + latAxis).substring(0, 4);
String coordSym = null;
CoordinateSystem coords;
if (lonType.equals("RA--") && latType.equals("DEC-")) {
coordSym = frame() + equinox();
} else {
if (lonType.charAt(0) != latType.charAt(0)) {
throw new TransformationException(
"Inconsistent axes definitions:" + lonType + "," + latType);
}
if (lonType.equals("GLON")) {
coordSym = "G";
} else if (lonType.equals("ELON")) {
coordSym = "E" + equinox();
} else if (lonType.equals("HLON")) {
coordSym = "H" + equinox();
}
}
coords = CoordinateSystem.factory(coordSym);
this.csys = coords;
add(coords.getSphereDistorter());
add(coords.getRotater());
}
/** Handle the NEAT special projection */
private void doNeatWCS() throws TransformationException {
// The NEAT transformation from the standard spherical system
// includes:
// Transformation to J2000 spherical coordinates (a null operation)
// A tangent plane projection to the standard plane
// A scaler transformation to corrected pixel coordinates.
// A distorter to distorted pixel coordinates
// A scaler transformation of distorted coordinates to actual pixels
CoordinateSystem csys = CoordinateSystem.factory("J2000");
this.csys = csys;
// The RA0/DEC0 pair are the actual center of the projection.
double cv1 = toRadians(h.getDoubleValue("RA0"));
double cv2 = toRadians(h.getDoubleValue("DEC0"));
wcsKeys.put("CRVAL1", toDegrees(cv1));
wcsKeys.put("CRVAL2", toDegrees(cv2));
Projection proj = new Projection("Tan", new double[] {cv1, cv2});
this.proj = proj;
double cd1 = toRadians(h.getDoubleValue("CDELT1"));
double cd2 = toRadians(h.getDoubleValue("CDELT2"));
wcsKeys.put("CDELT1", toDegrees(cd1));
wcsKeys.put("CDELT2", toDegrees(cd2));
wcsScale = abs(cd1);
double cp1 = h.getDoubleValue("CRPIX1");
double cp2 = h.getDoubleValue("CRPIX2");
wcsKeys.put("CPRIX1", cp1);
wcsKeys.put("CRPIX2", cp2);
wcsKeys.put("CTYPE1", "RA---XTN");
wcsKeys.put("CTYPE2", "DEC--XTN");
Scaler s1 = new Scaler(0., 0., -1 / cd1, 0, 0, -1 / cd2);
// Note that the the A0,A1,A2, B0,B1,B2 rotation
// is relative to the original pixel values, so
// we need to put this in the secondary scaler.
//
double x0 = h.getDoubleValue("X0");
double y0 = h.getDoubleValue("Y0");
Distorter dis =
new skyview.geometry.distorter.Neat(
h.getDoubleValue("RADIAL"), h.getDoubleValue("XRADIAL"), h.getDoubleValue("YRADIAL"));
double a0 = h.getDoubleValue("A0");
double a1 = h.getDoubleValue("A1");
double a2 = h.getDoubleValue("A2");
double b0 = h.getDoubleValue("B0");
double b1 = h.getDoubleValue("B1");
double b2 = h.getDoubleValue("B2");
// The reference pixel is to be computed in the distorted frame.
double[] cpix = new double[] {cp1, cp2};
double[] cout = new double[2];
dis.transform(cpix, cout);
Scaler s2 =
new Scaler(
cout[0] - a0 - a1 * x0 - a2 * y0,
cout[1] - b0 - b2 * x0 - b1 * y0,
-(1 + a1),
-a2,
-b2,
-(1 + b1));
wcsKeys.put("A0", a0);
wcsKeys.put("A1", a1);
wcsKeys.put("A2", a2);
wcsKeys.put("B0", b0);
wcsKeys.put("B1", b1);
wcsKeys.put("B2", b2);
this.distort = dis;
add(csys.getSphereDistorter());
add(csys.getRotater());
add(proj.getRotater());
add(proj.getProjecter());
this.scale = s1;
// Note that s1 is defined from the projection plane to the pixels coordinates,
// so we don't need to invert it.
//
// But the second scaler, s2, used in the NEAT correction
// is defined in the direction from pixels to sphere, so we
// need to take its inverse.
this.scale = this.scale.add(s2.inverse());
add(this.scale);
add(dis);
}
/** Handle a DSS projection */
private void doDSSWCS() throws TransformationException {
double plateRA =
h.getDoubleValue("PLTRAH")
+ h.getDoubleValue("PLTRAM") / 60
+ h.getDoubleValue("PLTRAS") / 3600;
plateRA = toRadians(15 * plateRA);
wcsKeys.put("PLTRAH", h.getDoubleValue("PLTRAH"));
wcsKeys.put("PLTRAM", h.getDoubleValue("PLTRAM"));
wcsKeys.put("PLTRAS", h.getDoubleValue("PLTRAS"));
double plateDec =
h.getDoubleValue("PLTDECD")
+ h.getDoubleValue("PLTDECM") / 60
+ h.getDoubleValue("PLTDECS") / 3600;
plateDec = toRadians(plateDec);
if (h.getStringValue("PLTDECSN").substring(0, 1).equals("-")) {
plateDec = -plateDec;
}
wcsKeys.put("PLTDECD", h.getDoubleValue("PLTDECD"));
wcsKeys.put("PLTDECM", h.getDoubleValue("PLTDECM"));
wcsKeys.put("PLTDECS", h.getDoubleValue("PLTDECS"));
wcsKeys.put("PLTDECSN", h.getStringValue("PLTDECSN"));
double plateScale = h.getDoubleValue("PLTSCALE");
double xPixelSize = h.getDoubleValue("XPIXELSZ");
double yPixelSize = h.getDoubleValue("YPIXELSZ");
wcsKeys.put("PLTSCALE", plateScale);
wcsKeys.put("XPIXELSZ", xPixelSize);
wcsKeys.put("YPIXELSZ", yPixelSize);
double[] xCoeff = new double[20];
double[] yCoeff = new double[20];
for (int i = 1; i <= 20; i += 1) {
xCoeff[i - 1] = h.getDoubleValue("AMDX" + i);
yCoeff[i - 1] = h.getDoubleValue("AMDY" + i);
wcsKeys.put("AMDX" + i, xCoeff[i - 1]);
wcsKeys.put("AMDY" + i, yCoeff[i - 1]);
}
double[] ppo = new double[6];
for (int i = 1; i <= 6; i += 1) {
ppo[i - 1] = h.getDoubleValue("PPO" + i);
wcsKeys.put("PPO" + i, ppo[i - 1]);
}
double plateCenterX = ppo[2];
double plateCenterY = ppo[5];
double cdelt1 = -plateScale / 1000 * xPixelSize / 3600;
double cdelt2 = plateScale / 1000 * yPixelSize / 3600;
wcsScale = abs(cdelt1);
// This gives cdelts in degrees per pixel.
// CNPIX pixels use a have the first pixel going from 1 - 2 so they are
// off by 0.5 from FITS (which in turn is offset by 0.5 from the internal
// scaling, but we handle that elsewhere).
double crpix1 = plateCenterX / xPixelSize - h.getDoubleValue("CNPIX1", 0) - 0.5;
double crpix2 = plateCenterY / yPixelSize - h.getDoubleValue("CNPIX2", 0) - 0.5;
wcsKeys.put("CNPIX1", h.getDoubleValue("CNPIX1", 0));
wcsKeys.put("CNPIX2", h.getDoubleValue("CNPIX2", 0));
Projection proj = new Projection("Tan", new double[] {plateRA, plateDec});
this.proj = proj;
CoordinateSystem coords = CoordinateSystem.factory("J2000");
this.csys = coords;
cdelt1 = toRadians(cdelt1);
cdelt2 = toRadians(cdelt2);
Scaler s = new Scaler(-cdelt1 * crpix1, -cdelt2 * crpix2, cdelt1, 0, 0, cdelt2);
// Got the transformers ready. Add them in properly.
add(coords.getSphereDistorter());
add(coords.getRotater());
add(proj.getRotater());
add(proj.getProjecter());
this.distort =
new skyview.geometry.distorter.DSS(
plateRA, plateDec, xPixelSize, yPixelSize, plateScale, ppo, xCoeff, yCoeff);
add(this.distort);
this.scale = s.inverse();
add(this.scale);
}