/** Get the scaling when it is described as a matrix */
private boolean extractScaler2(double crpix1, double crpix2) throws TransformationException {
// Look for the CD matrix...
//
double m11 = h.getDoubleValue("CD" + lonAxis + "_" + lonAxis, NaN);
double m12 = h.getDoubleValue("CD" + lonAxis + "_" + latAxis, NaN);
double m21 = h.getDoubleValue("CD" + latAxis + "_" + lonAxis, NaN);
double m22 = h.getDoubleValue("CD" + latAxis + "_" + latAxis, NaN);
boolean matrix = !isNaN(m11 + m12 + m21 + m22);
if (!matrix) {
return false;
}
wcsKeys.put("CD1_1", m11);
wcsKeys.put("CD1_2", m12);
wcsKeys.put("CD2_1", m21);
wcsKeys.put("CD2_2", m22);
m11 = toRadians(m11);
m12 = toRadians(m12);
m21 = toRadians(m21);
m22 = toRadians(m22);
// we have
// t = a11 (x-x0) + a12 (y-y0); u = a21(x-x0) + a22(y-y0)
// t = a11x + a12y - a11 x0 - a12 y0;
//
Scaler s =
new Scaler(-m11 * crpix1 - m12 * crpix2, -m21 * crpix1 - m22 * crpix2, m11, m12, m21, m22);
s = s.inverse();
// Are longitude and latitude in unusual order?
if (lonAxis > latAxis) {
s.interchangeAxes();
}
this.scale = s;
add(s);
setWCSScale(s);
return true;
}
/** Get the scaling when CDELT is specified */
private boolean extractScaler1(double crpix1, double crpix2) throws TransformationException {
boolean matrix = false;
double cdelt1 = h.getDoubleValue("CDELT" + lonAxis, NaN);
double cdelt2 = h.getDoubleValue("CDELT" + latAxis, NaN);
wcsKeys.put("CDELT1", cdelt1);
wcsKeys.put("CDELT2", cdelt2);
if (isNaN(cdelt1) || isNaN(cdelt2)) {
return false;
}
// We use 1 indexing to match better with the FITS files.
double m11, m12, m21, m22;
// We've got minimal information... We might have more.
double crota = h.getDoubleValue("CROTA" + latAxis, NaN);
if (!isNaN(crota) && crota != 0) {
wcsKeys.put("CROTA2", crota);
crota = toRadians(crota);
m11 = cos(crota);
m12 = sin(crota);
m21 = -sin(crota);
m22 = cos(crota);
matrix = true;
} else {
m11 = h.getDoubleValue("PC" + lonAxis + "_" + lonAxis, NaN);
m12 = h.getDoubleValue("PC" + lonAxis + "_" + latAxis, NaN);
m21 = h.getDoubleValue("PC" + latAxis + "_" + lonAxis, NaN);
m22 = h.getDoubleValue("PC" + latAxis + "_" + latAxis, NaN);
matrix = !isNaN(m11 + m12 + m21 + m22);
if (matrix) {
wcsKeys.put("PC1_1", m11);
wcsKeys.put("PC1_2", m12);
wcsKeys.put("PC2_1", m21);
wcsKeys.put("PC2_2", m22);
}
}
// Note that Scaler is defined with parameters t = x0 + a00 x + a01 y; u = y0 + a10 x + a11 y
// which is different from what we have here...
// t = scalex (x-x0), u = scaley (y-y0)
// t = scalex x - scalex x0; u = scaley y - scaley y0
// or
// t = scalex [a11 (x-x0) + a12 (y-y0)], u = scaley [a21 (x-x0) + a22 (y-y0)] ->
// t = scalex a11 x - scalex a11 x0 + scalex a12 y + scalex a12 y0 ->
// t = - scalex (a11 x0 + a12 y0) + scalex a11 x + scalex a12 y (and similarly for u)
Scaler s;
cdelt1 = toRadians(cdelt1);
cdelt2 = toRadians(cdelt2);
if (!matrix) {
s = new Scaler(-cdelt1 * crpix1, -cdelt2 * crpix2, cdelt1, 0, 0, cdelt2);
} else {
s =
new Scaler(
-cdelt1 * (m11 * crpix1 + m12 * crpix2),
-cdelt2 * (m21 * crpix1 + m22 * crpix2),
cdelt1 * m11,
cdelt1 * m12,
cdelt2 * m21,
cdelt2 * m22);
}
// Note that this scaler transforms from pixel coordinates to standard projection
// plane coordinates. We want the inverse transformation as the scaler.
s = s.inverse();
// Are lon and lat in unusual order?
if (lonAxis > latAxis) {
s.interchangeAxes();
}
this.scale = s;
add(s);
setWCSScale(s);
return true;
}
