move skycell wcs reading into resample

romancal/patch_match/patch_match.py

@@ -7,13 +7,19 @@
 import logging
 import os
 import os.path
+import re
 
 import asdf
 import gwcs.wcs as wcs
 import numpy as np
 import spherical_geometry.polygon as sgp
 import spherical_geometry.vector as sgv
+from astropy import coordinates
+from astropy import units as u
+from astropy.modeling import models
+from gwcs import WCS, coordinate_frames
 from spherical_geometry.vector import normalize_vector
+from stcal.alignment import util as wcs_util
 
 log = logging.getLogger(__name__)
 log.setLevel(logging.DEBUG)
@@ -252,3 +258,131 @@ def veccoords_to_tangent_plane(vertices, tangent_point_vec):
     x_coords = np.dot(x_axis, avertices) * RAD_TO_ARCSEC
     y_coords = np.dot(y_axis, avertices) * RAD_TO_ARCSEC
     return x_coords, y_coords
+
+
+def wcsinfo_to_wcs(wcsinfo, bounding_box=None, name="wcsinfo"):
+    """Create a GWCS from the L3 wcsinfo meta
+
+    Parameters
+    ----------
+    wcsinfo : dict or MosaicModel.meta.wcsinfo
+        The L3 wcsinfo to create a GWCS from.
+
+    bounding_box : None or 4-tuple
+        The bounding box in detector/pixel space. Form of input is:
+        (x_left, x_right, y_bottom, y_top)
+
+    name : str
+        Value of the `name` attribute of the GWCS object.
+
+    Returns
+    -------
+    wcs : wcs.GWCS
+        The GWCS object created.
+    """
+    pixelshift = models.Shift(-wcsinfo["x_ref"], name="crpix1") & models.Shift(
+        -wcsinfo["y_ref"], name="crpix2"
+    )
+    pixelscale = models.Scale(wcsinfo["pixel_scale"], name="cdelt1") & models.Scale(
+        wcsinfo["pixel_scale"], name="cdelt2"
+    )
+    tangent_projection = models.Pix2Sky_TAN()
+    celestial_rotation = models.RotateNative2Celestial(
+        wcsinfo["ra_ref"], wcsinfo["dec_ref"], 180.0
+    )
+
+    matrix = wcsinfo.get("rotation_matrix", None)
+    if matrix:
+        matrix = np.array(matrix)
+    else:
+        orientat = wcsinfo.get("orientat", 0.0)
+        matrix = wcs_util.calc_rotation_matrix(
+            np.deg2rad(orientat), v3i_yangle=0.0, vparity=1
+        )
+        matrix = np.reshape(matrix, (2, 2))
+    rotation = models.AffineTransformation2D(matrix, name="pc_rotation_matrix")
+    det2sky = (
+        pixelshift | rotation | pixelscale | tangent_projection | celestial_rotation
+    )
+
+    detector_frame = coordinate_frames.Frame2D(
+        name="detector", axes_names=("x", "y"), unit=(u.pix, u.pix)
+    )
+    sky_frame = coordinate_frames.CelestialFrame(
+        reference_frame=coordinates.ICRS(), name="icrs", unit=(u.deg, u.deg)
+    )
+    wcsobj = WCS([(detector_frame, det2sky), (sky_frame, None)], name=name)
+
+    if bounding_box:
+        wcsobj.bounding_box = bounding_box
+
+    return wcsobj
+
+
+def skycell_to_wcs(skycell_record):
+    """From a skycell record, generate a GWCS
+
+    Parameters
+    ----------
+    skycell_record : dict
+        A skycell record, or row, from the skycell patches table.
+
+    Returns
+    -------
+    wcsobj : wcs.GWCS
+        The GWCS object from the skycell record.
+    """
+    wcsinfo = dict()
+
+    # The scale is given in arcseconds per pixel. Convert to degrees.
+    wcsinfo["pixel_scale"] = float(skycell_record["pixel_scale"]) / 3600.0
+
+    # Remaining components of the wcsinfo block
+    wcsinfo["ra_ref"] = float(skycell_record["ra_projection_center"])
+    wcsinfo["dec_ref"] = float(skycell_record["dec_projection_center"])
+    wcsinfo["x_ref"] = float(skycell_record["x0_projection"])
+    wcsinfo["y_ref"] = float(skycell_record["y0_projection"])
+    wcsinfo["orientat"] = float(skycell_record["orientat_projection_center"])
+    wcsinfo["rotation_matrix"] = None
+
+    # Bounding box of the skycell. Note that the center of the pixels are at (0.5, 0.5)
+    bounding_box = (
+        (-0.5, -0.5 + skycell_record["nx"]),
+        (-0.5, -0.5 + skycell_record["ny"]),
+    )
+
+    wcsobj = wcsinfo_to_wcs(wcsinfo, bounding_box=bounding_box)
+
+    wcsobj.array_shape = tuple(
+        int(axs[1] - axs[0] + 0.5)
+        for axs in wcsobj.bounding_box.bounding_box(order="C")
+    )
+    return wcsobj
+
+
+def to_skycell_wcs(input):
+    # check to see if the product name contains a skycell name & if true get the skycell record
+    if "target" not in input.asn:
+        return None
+    skycell_name = input.asn["target"]
+
+    if not re.match(r"r\d{3}\w{2}\d{2}x\d{2}y\d{2}", skycell_name):
+        return None
+
+    if "skycell_wcs_info" in input.asn and input.asn["skycell_wcs_info"] != "none":
+        skycell_record = input.asn["skycell_wcs_info"]
+    else:
+        if PATCH_TABLE is None:
+            load_patch_table()
+        skycell_record = PATCH_TABLE[
+            np.where(PATCH_TABLE["name"][:] == skycell_name)[0][0]
+        ]
+    log.info("Skycell record %s:", skycell_record)
+
+    # extract the wcs info from the record for skycell_to_wcs
+    log.info(
+        "Creating skycell image at ra: %f  dec %f",
+        float(skycell_record["ra_center"]),
+        float(skycell_record["dec_center"]),
+    )
+    return skycell_to_wcs(skycell_record)

romancal/pipeline/tests/test_mosaic_pipeline.py → romancal/patch_match/tests/test_skycell_wcs.py

@@ -1,8 +1,8 @@
-"""Unit tests for the mosaic pipeline"""
+"""Unit tests for skycell wcs functions"""
 
 import numpy as np
 
-import romancal.pipeline.mosaic_pipeline as mp
+from romancal.patch_match.patch_match import skycell_to_wcs, wcsinfo_to_wcs
 
 
 def test_skycell_to_wcs():
@@ -61,7 +61,7 @@ def test_skycell_to_wcs():
         ],
     )
 
-    wcs = mp.skycell_to_wcs(skycell)
+    wcs = skycell_to_wcs(skycell)
 
     assert np.allclose(
         wcs(
@@ -112,7 +112,7 @@ def test_wcsinfo_to_wcs():
         "orientat": 359.8466793994546,
     }
 
-    wcs = mp.wcsinfo_to_wcs(wcsinfo)
+    wcs = wcsinfo_to_wcs(wcsinfo)
 
     assert np.allclose(
         wcs(wcsinfo["x_ref"], wcsinfo["y_ref"]), (wcsinfo["ra_ref"], wcsinfo["dec_ref"])