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DM-51741 Make hips pixel checks optional. #812

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Merged
natelust merged 1 commit into from
Jan 26, 2026
Merged

DM-51741 Make hips pixel checks optional. #812

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20 changes: 14 additions & 6 deletions python/lsst/afw/geom/_hpxUtils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@
from ._geom import makeSkyWcs


def makeHpxWcs(hips_order, pixel, shift_order=9):
def makeHpxWcs(hips_order, pixel, shift_order=9, validate_pixel_id=True):
"""
Make a SkyWcs object with HEALPix grid projection (HPX).

Expand All @@ -54,6 +54,10 @@ def makeHpxWcs(hips_order, pixel, shift_order=9):
Shift order for subpixels, such that there are 2**shift_order
sub-pixels on a side of the HiPS cell.
Must be a positive integer.
validate_pixel_id : `bool`, optional
If true validate that the pixel number is in range for the given
hips_order.


Returns
-------
Expand All @@ -63,7 +67,7 @@ def makeHpxWcs(hips_order, pixel, shift_order=9):
------
`ValueError`: Raise if hips_order is <=0, or if shift_order is <=0, or
if pixel number is out of range for the given hips_order
(0 <= pixel < 12*nside*nside).
(0 <= pixel < 12*nside*nside) and validate_pixel_id is True.

Notes
-----
Expand Down Expand Up @@ -100,7 +104,7 @@ def makeHpxWcs(hips_order, pixel, shift_order=9):
raise ValueError(f"order {hips_order} must be positive.")
nside_cell = 2**hips_order

if pixel < 0 or pixel >= 12*nside_cell*nside_cell:
if validate_pixel_id and pixel < 0 or pixel >= 12*nside_cell*nside_cell:
raise ValueError(f"pixel value {pixel} out of range.")

# The HEALPix grid projection (HPX) is defined in the FITS standard
Expand Down Expand Up @@ -129,7 +133,7 @@ def makeHpxWcs(hips_order, pixel, shift_order=9):
# a non-trivial computation, and typically is outside of the
# tile pixel itself. Therefore, these values are not the same
# as the values computed from HEALPix `pix2ang()`.
cent_ra_proj, cent_dec_proj = _hpx_projected_center(hips_order, pixel)
cent_ra_proj, cent_dec_proj = _hpx_projected_center(hips_order, pixel, validate_pixel_id)

md = PropertySet()
md['CD1_1'] = -cos45_scale
Expand All @@ -148,7 +152,7 @@ def makeHpxWcs(hips_order, pixel, shift_order=9):
return makeSkyWcs(md)


def _hpx_projected_center(hips_order, pixel):
def _hpx_projected_center(hips_order, pixel, validate_pixel_id):
"""
Compute the projected center for use in HPX WCS headers.

Expand All @@ -166,6 +170,10 @@ def _hpx_projected_center(hips_order, pixel):
HiPS order, such that HEALPix nside=2**hips_order.
pixel : `int`
Pixel number in the nest ordering scheme.
validate_pixel_id : `bool`, optional
If true validate that the pixel number is in range for the given
hips_order.


Returns
-------
Expand All @@ -181,7 +189,7 @@ def _hpx_projected_center(hips_order, pixel):
raise ValueError(f"hips_order {hips_order} must be positive.")
nside_cell = 2**hips_order

if pixel < 0 or pixel >= 12*nside_cell*nside_cell:
if validate_pixel_id and pixel < 0 or pixel >= 12*nside_cell*nside_cell:
raise ValueError(f"pixel value {pixel} out of range.")

twice_depth = np.left_shift(hips_order, 1)
Expand Down