WCS.jl

WCSTransform(naxis; kwds...)

Construct a WCS transformation with the given number of axes naxis. Keyword arguments can be passed to set various attributes of the transform. Specifying keyword arguments is equivalent to setting them after construction:

julia> wcs = WCSTransform(2; crpix=[1000., 1000.])
WCSTransform(naxis=2, cdelt=[1.0, 1.0], crval=[0.0, 0.0], crpix=[1000.0, 1000.0])

is equivalent to:

julia> wcs = WCSTransform(2)
WCSTransform(naxis=2, cdelt=[1.0, 1.0], crval=[0.0, 0.0], crpix=[0.0, 0.0])

julia> wcs.crpix = [1000., 1000.];

julia> wcs
WCSTransform(naxis=2, cdelt=[1.0, 1.0], crval=[0.0, 0.0], crpix=[1000.0, 1000.0])

Properties

Below is the entire list of public properties for a WCSTransform

from_header(header[; relax=WCS.HDR_ALL, ctrl=0, ignore_rejected=false, table=false])

Parse the FITS image header in the String header, returning a Vector{WCSTransform} giving all the transforms defined in the header. The relax determines the treatment of non-standard keywords. The default is to accept all known non-standard keywords. Use relax=WCS.HDR_NONE to ignore all non-standard keywords. Use, e.g., relax=(WCS.HDR_RADECSYS & WCS.HDR_CROTAia) to only accept selected non-standard keywords.

obsfix(ctrl::Integer, wcs::WCSTransform)

Complete the obsgeo field wcs of observatory coordinates. That is, if only the (x,y,z) Cartesian coordinate triplet or the (l,b,h) geodetic coordinate triplet are set, then it derives the other triplet from it. If both triplets are set, then it checks for consistency at the level of 1 metre.

Parameters

• ctrl: flag that controls behaviour if one triplet is defined and the other is only partially defined:
  • 0: Reset only the undefined elements of an incomplete coordinate triplet.
  • 1: Reset all elements of an incomplete triplet.
  • 2: Don't make any changes, check for consistency only. Returns an error if either of the two triplets is incomplete.
• wcs: Coordinate transformation parameters. Its obsgeo field may be changed.

Returns

• -1: No change required (not an error).
• 0: Success.
• 1: Null wcsprm pointer passed.
• 5: Invalid parameter value.

pix_to_world!(wcs, pixcoords, worldcoords[; stat, imcoords, phi, theta])

Convert the array of pixel coordinates pixcoords to world coordinates according to the WCSTransform wcs, storing the result in the worldcoords and stat arrays. pixcoords should be a 2-d array where pixcoords[:, i] is the i-th set of coordinates, or a 1-d array representing a single set of coordinates. worldcoords must be the same size and type as pixcoords.

If given, the arrays stat, imcoords, phi, theta will be used to store intermediate results. Their sizes and types must all match pixcoords, except for stat which should be the same size but of type Cint (typically Int32).

pix_to_world(wcs, pixcoords)

Convert the array of pixel coordinates pixcoords to world coordinates according to the WCSTransform wcs. pixcoords should be a 2-d array where pixcoords[:, i] is the i-th set of coordinates, or a 1-d array representing a single set of coordinates.

The return value is the same shape as pixcoords.

to_header(wcs[; relax=WCS.HDR_NONE])

Encode the WCSTransform wcs as a FITS header string. The relax keyword controls how non-standard extensions to the WCS standard are handled.

world_to_pix!(wcs, worldcoords, pixcoords[; stat, phi, theta, imcoords])

Convert the array of pixel coordinates worldcoords to pixel coordinates according to the WCSTransform wcs, storing the result in the pixcoords array. worldcoords should be a 2-d array where worldcoords[:, i] is the i-th set of coordinates, or a 1-d array representing a single set of coordinates. pixcoords must be the same size and type as worldcoords.

If given, the arrays stat, imcoords, phi, theta will be used to store intermediate results. Their sizes and types must all match worldcoords, except for stat which should be the same size but of type Cint (typically Int32).

world_to_pix(wcs, worldcoords)

Convert the array of world coordinates worldcoords to pixel coordinates according to the WCSTransform wcs. worldcoords is a 2-d array where worldcoords[:, i] is the i-th set of coordinates, or a 1-d array representing a single set of coordinates.

The return value is the same size as worldcoords.