RF: Upgrade nitransforms and remove workarounds (#3378)

I've manually verified that `load_ants_h5()` can be replaced with
`nitransforms.manip.load()` and that this does the right thing, and that
using `nitransforms.apply(xfm, moving, target)` does indeed get me
basically the same thing as ANTs.

fmriprep/interfaces/resampling.py

@@ -6,6 +6,7 @@
 
 import nibabel as nb
 import nitransforms as nt
+import nitransforms.resampling
 import numpy as np
 from nipype.interfaces.base import (
     File,
@@ -689,7 +690,7 @@ def reconstruct_fieldmap(
     )
 
     if not direct:
-        fmap_img = transforms.apply(fmap_img, reference=target)
+        fmap_img = nt.resampling.apply(transforms, fmap_img, reference=target)
 
     fmap_img.header.set_intent('estimate', name='fieldmap Hz')
     fmap_img.header.set_data_dtype('float32')

fmriprep/utils/transforms.py

@@ -2,12 +2,7 @@
 
 from pathlib import Path
 
-import h5py
-import nibabel as nb
 import nitransforms as nt
-import numpy as np
-from nitransforms.io.itk import ITKCompositeH5
-from transforms3d.affines import compose as compose_affine
 
 
 def load_transforms(xfm_paths: list[Path], inverse: list[bool]) -> nt.base.TransformBase:
@@ -24,7 +19,8 @@ def load_transforms(xfm_paths: list[Path], inverse: list[bool]) -> nt.base.Trans
     for path, inv in zip(xfm_paths[::-1], inverse[::-1], strict=False):
         path = Path(path)
         if path.suffix == '.h5':
-            xfm = load_ants_h5(path)
+            # Load as a TransformChain
+            xfm = nt.manip.load(path)
         else:
             xfm = nt.linear.load(path)
         if inv:
@@ -34,72 +30,5 @@ def load_transforms(xfm_paths: list[Path], inverse: list[bool]) -> nt.base.Trans
         else:
             chain += xfm
     if chain is None:
-        chain = nt.base.TransformBase()
+        chain = nt.Affine()  # Identity
     return chain
-
-
-def load_ants_h5(filename: Path) -> nt.base.TransformBase:
-    """Load ANTs H5 files as a nitransforms TransformChain"""
-    # Borrowed from https://github.com/feilong/process
-    # process.resample.parse_combined_hdf5()
-    #
-    # Changes:
-    #   * Tolerate a missing displacement field
-    #   * Return the original affine without a round-trip
-    #   * Always return a nitransforms TransformBase
-    #   * Construct warp affine from fixed parameters
-    #
-    # This should be upstreamed into nitransforms
-    h = h5py.File(filename)
-    xform = ITKCompositeH5.from_h5obj(h)
-
-    # nt.Affine
-    transforms = [nt.Affine(xform[0].to_ras())]
-
-    if '2' not in h['TransformGroup']:
-        return transforms[0]
-
-    transform2 = h['TransformGroup']['2']
-
-    # Confirm these transformations are applicable
-    if transform2['TransformType'][:][0] not in (
-        b'DisplacementFieldTransform_float_3_3',
-        b'DisplacementFieldTransform_double_3_3',
-    ):
-        msg = 'Unknown transform type [2]\n'
-        for i in h['TransformGroup'].keys():
-            msg += f'[{i}]: {h["TransformGroup"][i]["TransformType"][:][0]}\n'
-        raise ValueError(msg)
-
-    # Warp field fixed parameters as defined in
-    # https://itk.org/Doxygen/html/classitk_1_1DisplacementFieldTransform.html
-    shape = transform2['TransformFixedParameters'][:3]
-    origin = transform2['TransformFixedParameters'][3:6]
-    spacing = transform2['TransformFixedParameters'][6:9]
-    direction = transform2['TransformFixedParameters'][9:].reshape((3, 3))
-
-    # We are not yet confident that we handle non-unit spacing
-    # or direction cosine ordering correctly.
-    # If we confirm or fix, we can remove these checks.
-    if not np.allclose(spacing, 1):
-        raise ValueError(f'Unexpected spacing: {spacing}')
-    if not np.allclose(direction, direction.T):
-        raise ValueError(f'Asymmetric direction matrix: {direction}')
-
-    # ITK uses LPS affines
-    lps_affine = compose_affine(T=origin, R=direction, Z=spacing)
-    ras_affine = np.diag([-1, -1, 1, 1]) @ lps_affine
-
-    # ITK stores warps in Fortran-order, where the vector components change fastest
-    # Vectors are in mm LPS
-    itk_warp = np.reshape(
-        transform2['TransformParameters'],
-        (3, *shape.astype(int)),
-        order='F',
-    )
-
-    # Nitransforms warps are in RAS, with the vector components changing slowest
-    nt_warp = itk_warp.transpose(1, 2, 3, 0) * np.array([-1, -1, 1])
-
-    transforms.insert(0, nt.DenseFieldTransform(nb.Nifti1Image(nt_warp, ras_affine)))
-    return nt.TransformChain(transforms)

fmriprep/workflows/bold/registration.py

@@ -737,6 +737,7 @@ def _conditional_downsampling(in_file, in_mask, zoom_th=4.0):
     import nibabel as nb
     import nitransforms as nt
     import numpy as np
+    from nitransforms.resampling import apply as applyxfm
     from scipy.ndimage.filters import gaussian_filter
 
     img = nb.load(in_file)
@@ -756,14 +757,16 @@ def _conditional_downsampling(in_file, in_mask, zoom_th=4.0):
     offset = old_center - newrot.dot((newshape - 1) * 0.5)
     newaffine = nb.affines.from_matvec(newrot, offset)
 
+    identity = nt.Affine()
+
     newref = nb.Nifti1Image(np.zeros(newshape, dtype=np.uint8), newaffine)
-    nt.Affine(reference=newref).apply(img).to_filename(out_file)
+    applyxfm(identity, img, reference=newref).to_filename(out_file)
 
     mask = nb.load(in_mask)
     mask.set_data_dtype(float)
     mdata = gaussian_filter(mask.get_fdata(dtype=float), scaling)
     floatmask = nb.Nifti1Image(mdata, mask.affine, mask.header)
-    newmask = nt.Affine(reference=newref).apply(floatmask)
+    newmask = applyxfm(identity, floatmask, reference=newref)
     hdr = newmask.header.copy()
     hdr.set_data_dtype(np.uint8)
     newmaskdata = (newmask.get_fdata(dtype=float) > 0.5).astype(np.uint8)

pyproject.toml

@@ -25,7 +25,7 @@ dependencies = [
     "nipype >= 1.8.5",
     "nireports >= 23.2.2",
     "nitime",
-    "nitransforms >= 21.0.0, != 24.0.0",
+    "nitransforms >= 24.0.2",
     "niworkflows >= 1.11.0",
     "numpy >= 1.22",
     "packaging",

requirements.txt

@@ -232,7 +232,7 @@ nireports==23.2.2
     # via fmriprep (pyproject.toml)
 nitime==0.10.2
     # via fmriprep (pyproject.toml)
-nitransforms==23.0.1
+nitransforms==24.0.2
     # via
     #   fmriprep (pyproject.toml)
     #   niworkflows