/// <summary>
/// Parses the WCS records into a <see cref="WCSViaProjection"/>.
/// </summary>
/// <param name="Header">Image header.</param>
private static WCSViaProjection ParseWCS(HeaderTable Header)
{
/* Parse axis types and projection algorithm */
string Axis1 = Header["CTYPE1"].AsString;
string Axis2 = Header["CTYPE2"].AsString;
string Algorithm = Axis1.Substring(5, 3);
string Nm1 = Axis1.Substring(0, 4);
string Nm2 = Axis2.Substring(0, 4);
/* Parses the order of the axes and checks consistency of projection algorithm between the axes. */
bool RAFirst;
if (Nm1.ToUpper() == "RA--" && Nm2.ToUpper() == "DEC-")
{
RAFirst = true;
}
else if (Nm1.ToUpper() == "DEC-" && Nm2.ToUpper() == "RA--")
{
RAFirst = false;
}
else
{
throw new FITSFormatException("Cannot understand axis format");
}
if (Axis2.Substring(5, 3) != Algorithm)
{
throw new Exception("Projection Algorithm Mismatch.");
}
/* Computes the linear transformation part of the WCS projection */
WCSLinPart linpart;
double RA0 = (RAFirst ? Header["CRVAL1"] : Header["CRVAL2"]).FloatingPoint;
double Dec0 = (RAFirst ? Header["CRVAL2"] : Header["CRVAL1"]).FloatingPoint;
double X0 = Header["CRPIX1"].FloatingPoint;
double Y0 = Header["CRPIX2"].FloatingPoint;
double CD1_1 = ReadHeaderFloat("CD1_1", 0, Header);
double CD1_2 = ReadHeaderFloat("CD1_2", 0, Header);
double CD2_1 = ReadHeaderFloat("CD2_1", 0, Header);
double CD2_2 = ReadHeaderFloat("CD2_2", 0, Header);
if (RAFirst)
{
linpart = new WCSLinPart(CD1_1, CD1_2, CD2_1, CD2_2, X0, Y0);
}
else
{
linpart = new WCSLinPart(CD2_1, CD2_2, CD1_1, CD1_2, X0, Y0);
}
/* Finds the appropriate projection transform */
WCSProjectionTransform ipt;
if (Header["CUNIT1"].AsString != "deg " || Header["CUNIT2"].AsString != "deg ")
{
throw new FITSFormatException("Unknown unit types for WCS axes.");
}
try { ipt = Umbrella2.WCS.Projections.WCSProjections.GetProjectionTransform(Algorithm, RA0 * Math.PI / 180, Dec0 * Math.PI / 180); }
catch (KeyNotFoundException ex) { throw new FITSFormatException("Cannot understand projection algorithm", ex); }
return(new WCSViaProjection(ipt, linpart));
}
/// <summary>
/// Retrieves an image from a FITS file.
/// </summary>
/// <param name="File">Input file.</param>
/// <param name="Number">Image number in multi-image (MEF) FITS files.</param>
public FitsImage(FitsFile File, int Number = 0) : this()
{
ImageNumber = Number;
if (Number == 0)
{
Header = File.PrimaryTable;
}
else
{
Header = File.MEFHeaderTable[Number - 1];
}
try
{
/* Parse image size */
Width = (uint)Header["NAXIS1"].Int;
Height = (uint)Header["NAXIS2"].Int;
if (Width > MaxSize || Height > MaxSize)
{
throw new FITSFormatException("Image too large for Umbrella2.");
}
/* Parse axis types and projection algorithm */
string Axis1 = Header["CTYPE1"].GetFixedString;
string Axis2 = Header["CTYPE2"].GetFixedString;
string Algorithm = Axis1.Substring(5, 3);
string Nm1 = Axis1.Substring(0, 4);
string Nm2 = Axis2.Substring(0, 4);
/* Parses the order of the axes and checks consistency of projection algorithm between the axes. */
if (Nm1.ToUpper() == "RA--" && Nm2.ToUpper() == "DEC-")
{
RAFirst = true;
}
else if (Nm1.ToUpper() == "DEC-" && Nm2.ToUpper() == "RA--")
{
RAFirst = false;
}
else
{
throw new FITSFormatException("Cannot understand axis format");
}
if (Axis2.Substring(5, 3) != Algorithm)
{
throw new Exception("Projection Algorithm Mismatch.");
}
/* Computes the linear transformation part of the WCS projection */
double RA0 = (RAFirst ? Header["CRVAL1"] : Header["CRVAL2"]).FloatingPoint;
double Dec0 = (RAFirst ? Header["CRVAL2"] : Header["CRVAL1"]).FloatingPoint;
double X0 = Header["CRPIX1"].FloatingPoint;
double Y0 = Header["CRPIX2"].FloatingPoint;
WCSLinPart linpart;
if (RAFirst)
{
linpart = new WCSLinPart(Header["CD1_1"].FloatingPoint, Header["CD1_2"].FloatingPoint, Header["CD2_1"].FloatingPoint, Header["CD2_2"].FloatingPoint, X0, Y0);
}
else
{
linpart = new WCSLinPart(Header["CD2_1"].FloatingPoint, Header["CD2_2"].FloatingPoint, Header["CD1_1"].FloatingPoint, Header["CD1_2"].FloatingPoint, X0, Y0);
}
if (Header["CUNIT1"].GetFixedString != "deg " || Header["CUNIT2"].GetFixedString != "deg ")
{
throw new FITSFormatException("Wrong unit types for axes");
}
/* Retrieves the projection algorithm */
WCSProjectionTransform ipt;
try { ipt = Umbrella2.WCS.Projections.WCSProjections.GetProjectionTransform(Algorithm, RA0 * Math.PI / 180, Dec0 * Math.PI / 180); }
catch (KeyNotFoundException ex) { throw new FITSFormatException("Cannot understand projection algorithm", ex); }
Transform = new WCSViaProjection(ipt, linpart);
/* Computes BytesPerPixel and selects reading/writing functions */
BytesPerPixel = (byte)Math.Abs((Header["BITPIX"].Int / 8));
var RW = GetRW(Header["BITPIX"].Int);
Reader = RW.Item1;
Writer = RW.Item2;
/* Loads SWarp scaling to the properties dictionary */
try { GetProperty <KnownKeywords.SWarpScaling>(); }
catch { }
}
catch (Exception ex) { throw new FITSFormatException("Cannot understand FITS file.", ex); }
this.File = File;
}
