def test_homography_warper(self, batch_size, device, dtype):
# generate input data
height, width = 128, 64
eye_size = 3 # identity 3x3
patch_src = torch.ones(batch_size,
1,
height,
width,
device=device,
dtype=dtype)
# create base homography
dst_homo_src = utils.create_eye_batch(batch_size,
eye_size,
device=device,
dtype=dtype)
# instantiate warper
warper = kornia.geometry.transform.HomographyWarper(height,
width,
align_corners=True)
for _ in range(self.num_tests):
# generate homography noise
homo_delta = torch.rand_like(dst_homo_src) * 0.3
dst_homo_src_i = dst_homo_src + homo_delta
# transform the points from dst to ref
patch_dst = warper(patch_src, dst_homo_src_i)
patch_dst_to_src = warper(patch_dst,
_torch_inverse_cast(dst_homo_src_i))
# same transform precomputing the grid
warper.precompute_warp_grid(_torch_inverse_cast(dst_homo_src_i))
patch_dst_to_src_precomputed = warper(patch_dst)
assert_close(patch_dst_to_src_precomputed,
patch_dst_to_src,
atol=1e-4,
rtol=1e-4)
# projected should be equal as initial
error = utils.compute_patch_error(patch_src, patch_dst_to_src,
height, width)
assert error.item() < self.threshold
# check functional api
patch_dst_to_src_functional = kornia.geometry.transform.homography_warp(
patch_dst,
_torch_inverse_cast(dst_homo_src_i), (height, width),
align_corners=True)
assert_close(patch_dst_to_src,
patch_dst_to_src_functional,
atol=1e-4,
rtol=1e-4)
def normalize_homography3d(
dst_pix_trans_src_pix: torch.Tensor, dsize_src: Tuple[int, int, int], dsize_dst: Tuple[int, int, int]
) -> torch.Tensor:
r"""Normalize a given homography in pixels to [-1, 1].
Args:
dst_pix_trans_src_pix: homography/ies from source to destination to be
normalized. :math:`(B, 4, 4)`
dsize_src: size of the source image (depth, height, width).
dsize_src: size of the destination image (depth, height, width).
Returns:
the normalized homography.
Shape:
Output: :math:`(B, 4, 4)`
"""
if not isinstance(dst_pix_trans_src_pix, torch.Tensor):
raise TypeError(f"Input type is not a torch.Tensor. Got {type(dst_pix_trans_src_pix)}")
if not (len(dst_pix_trans_src_pix.shape) == 3 or dst_pix_trans_src_pix.shape[-2:] == (4, 4)):
raise ValueError(f"Input dst_pix_trans_src_pix must be a Bx3x3 tensor. Got {dst_pix_trans_src_pix.shape}")
# source and destination sizes
src_d, src_h, src_w = dsize_src
dst_d, dst_h, dst_w = dsize_dst
# compute the transformation pixel/norm for src/dst
src_norm_trans_src_pix: torch.Tensor = normal_transform_pixel3d(src_d, src_h, src_w).to(dst_pix_trans_src_pix)
src_pix_trans_src_norm = _torch_inverse_cast(src_norm_trans_src_pix)
dst_norm_trans_dst_pix: torch.Tensor = normal_transform_pixel3d(dst_d, dst_h, dst_w).to(dst_pix_trans_src_pix)
# compute chain transformations
dst_norm_trans_src_norm: torch.Tensor = dst_norm_trans_dst_pix @ (dst_pix_trans_src_pix @ src_pix_trans_src_norm)
return dst_norm_trans_src_norm
def denormalize_homography(
dst_pix_trans_src_pix: torch.Tensor, dsize_src: Tuple[int, int], dsize_dst: Tuple[int, int]
) -> torch.Tensor:
r"""De-normalize a given homography in pixels from [-1, 1] to actual height and width.
Args:
dst_pix_trans_src_pix: homography/ies from source to destination to be
denormalized. :math:`(B, 3, 3)`
dsize_src: size of the source image (height, width).
dsize_dst: size of the destination image (height, width).
Returns:
the denormalized homography of shape :math:`(B, 3, 3)`.
"""
if not isinstance(dst_pix_trans_src_pix, torch.Tensor):
raise TypeError(f"Input type is not a torch.Tensor. Got {type(dst_pix_trans_src_pix)}")
if not (len(dst_pix_trans_src_pix.shape) == 3 or dst_pix_trans_src_pix.shape[-2:] == (3, 3)):
raise ValueError(f"Input dst_pix_trans_src_pix must be a Bx3x3 tensor. Got {dst_pix_trans_src_pix.shape}")
# source and destination sizes
src_h, src_w = dsize_src
dst_h, dst_w = dsize_dst
# compute the transformation pixel/norm for src/dst
src_norm_trans_src_pix: torch.Tensor = normal_transform_pixel(src_h, src_w).to(dst_pix_trans_src_pix)
dst_norm_trans_dst_pix: torch.Tensor = normal_transform_pixel(dst_h, dst_w).to(dst_pix_trans_src_pix)
dst_denorm_trans_dst_pix = _torch_inverse_cast(dst_norm_trans_dst_pix)
# compute chain transformations
dst_norm_trans_src_norm: torch.Tensor = dst_denorm_trans_dst_pix @ (dst_pix_trans_src_pix @ src_norm_trans_src_pix)
return dst_norm_trans_src_norm
def normalize_homography(
dst_pix_trans_src_pix: torch.Tensor, dsize_src: Tuple[int, int], dsize_dst: Tuple[int, int]
) -> torch.Tensor:
r"""Normalize a given homography in pixels to [-1, 1].
Args:
dst_pix_trans_src_pix (torch.Tensor): homography/ies from source to destination to be
normalized. :math:`(B, 3, 3)`
dsize_src (tuple): size of the source image (height, width).
dsize_dst (tuple): size of the destination image (height, width).
Returns:
torch.Tensor: the normalized homography of shape :math:`(B, 3, 3)`.
"""
check_is_tensor(dst_pix_trans_src_pix)
if not (len(dst_pix_trans_src_pix.shape) == 3 or dst_pix_trans_src_pix.shape[-2:] == (3, 3)):
raise ValueError(
"Input dst_pix_trans_src_pix must be a Bx3x3 tensor. Got {}".format(dst_pix_trans_src_pix.shape)
)
# source and destination sizes
src_h, src_w = dsize_src
dst_h, dst_w = dsize_dst
# compute the transformation pixel/norm for src/dst
src_norm_trans_src_pix: torch.Tensor = normal_transform_pixel(src_h, src_w).to(dst_pix_trans_src_pix)
src_pix_trans_src_norm = _torch_inverse_cast(src_norm_trans_src_pix)
dst_norm_trans_dst_pix: torch.Tensor = normal_transform_pixel(dst_h, dst_w).to(dst_pix_trans_src_pix)
# compute chain transformations
dst_norm_trans_src_norm: torch.Tensor = dst_norm_trans_dst_pix @ (dst_pix_trans_src_pix @ src_pix_trans_src_norm)
return dst_norm_trans_src_norm
def warp_affine3d(
src: torch.Tensor,
M: torch.Tensor,
dsize: Tuple[int, int, int],
flags: str = 'bilinear',
padding_mode: str = 'zeros',
align_corners: bool = True,
) -> torch.Tensor:
r"""Apply a projective transformation a to 3d tensor.
.. warning::
This API signature it is experimental and might suffer some changes in the future.
Args:
src : input tensor of shape :math:`(B, C, D, H, W)`.
M: projective transformation matrix of shape :math:`(B, 3, 4)`.
dsize: size of the output image (depth, height, width).
mode: interpolation mode to calculate output values
``'bilinear'`` | ``'nearest'``.
padding_mode: padding mode for outside grid values
``'zeros'`` | ``'border'`` | ``'reflection'``.
align_corners : mode for grid_generation.
Returns:
torch.Tensor: the warped 3d tensor with shape :math:`(B, C, D, H, W)`.
.. note::
This function is often used in conjunction with :func:`get_perspective_transform3d`.
"""
if len(src.shape) != 5:
raise AssertionError(src.shape)
if not (len(M.shape) == 3 and M.shape[-2:] == (3, 4)):
raise AssertionError(M.shape)
if len(dsize) != 3:
raise AssertionError(dsize)
B, C, D, H, W = src.size()
size_src: Tuple[int, int, int] = (D, H, W)
size_out: Tuple[int, int, int] = dsize
M_4x4 = convert_affinematrix_to_homography3d(M) # Bx4x4
# we need to normalize the transformation since grid sample needs -1/1 coordinates
dst_norm_trans_src_norm: torch.Tensor = normalize_homography3d(
M_4x4, size_src, size_out) # Bx4x4
src_norm_trans_dst_norm = _torch_inverse_cast(dst_norm_trans_src_norm)
P_norm: torch.Tensor = src_norm_trans_dst_norm[:, :3] # Bx3x4
# compute meshgrid and apply to input
dsize_out: List[int] = [B, C] + list(size_out)
grid = torch.nn.functional.affine_grid(P_norm,
dsize_out,
align_corners=align_corners)
return torch.nn.functional.grid_sample(src,
grid,
align_corners=align_corners,
mode=flags,
padding_mode=padding_mode)
def test_values(self, device, dtype):
x = torch.tensor([[4.0, 7.0], [2.0, 6.0]], device=device, dtype=dtype)
y_expected = torch.tensor([[0.6, -0.7], [-0.2, 0.4]], device=device, dtype=dtype)
y = _torch_inverse_cast(x)
assert_close(y, y_expected)
def get_projective_transform(center: torch.Tensor, angles: torch.Tensor,
scales: torch.Tensor) -> torch.Tensor:
r"""Calculate the projection matrix for a 3D rotation.
.. warning::
This API signature it is experimental and might suffer some changes in the future.
The function computes the projection matrix given the center and angles per axis.
Args:
center: center of the rotation (x,y,z) in the source with shape :math:`(B, 3)`.
angles: angle axis vector containing the rotation angles in degrees in the form
of (rx, ry, rz) with shape :math:`(B, 3)`. Internally it calls Rodrigues to compute
the rotation matrix from axis-angle.
scales: scale factor for x-y-z-directions with shape :math:`(B, 3)`.
Returns:
the projection matrix of 3D rotation with shape :math:`(B, 3, 4)`.
.. note::
This function is often used in conjunction with :func:`warp_affine3d`.
"""
if not (len(center.shape) == 2 and center.shape[-1] == 3):
raise AssertionError(center.shape)
if not (len(angles.shape) == 2 and angles.shape[-1] == 3):
raise AssertionError(angles.shape)
if center.device != angles.device:
raise AssertionError(center.device, angles.device)
if center.dtype != angles.dtype:
raise AssertionError(center.dtype, angles.dtype)
# create rotation matrix
angle_axis_rad: torch.Tensor = K.deg2rad(angles)
rmat: torch.Tensor = K.angle_axis_to_rotation_matrix(
angle_axis_rad) # Bx3x3
scaling_matrix: torch.Tensor = K.eye_like(3, rmat)
scaling_matrix = scaling_matrix * scales.unsqueeze(dim=1)
rmat = rmat @ scaling_matrix.to(rmat)
# define matrix to move forth and back to origin
from_origin_mat = torch.eye(4)[None].repeat(rmat.shape[0], 1,
1).type_as(center) # Bx4x4
from_origin_mat[..., :3, -1] += center
to_origin_mat = from_origin_mat.clone()
to_origin_mat = _torch_inverse_cast(from_origin_mat)
# append translation with zeros
proj_mat = projection_from_Rt(rmat,
torch.zeros_like(center)[..., None]) # Bx3x4
# chain 4x4 transforms
proj_mat = convert_affinematrix_to_homography3d(proj_mat) # Bx4x4
proj_mat = from_origin_mat @ proj_mat @ to_origin_mat
return proj_mat[..., :3, :] # Bx3x4
def compute_inverse_transformation(self, transform: torch.Tensor):
"""Compute the inverse transform of given transformation matrices."""
return _torch_inverse_cast(transform)
def test_smoke(self, device, dtype, input_shape):
x = torch.rand(input_shape, device=device, dtype=dtype)
y = _torch_inverse_cast(x)
assert y.shape == x.shape
def warp_perspective(
src: torch.Tensor,
M: torch.Tensor,
dsize: Tuple[int, int],
mode: str = 'bilinear',
padding_mode: str = 'zeros',
align_corners: Optional[bool] = None,
) -> torch.Tensor:
r"""Applies a perspective transformation to an image.
.. image:: https://kornia-tutorials.readthedocs.io/en/latest/_images/warp_perspective_10_2.png
The function warp_perspective transforms the source image using
the specified matrix:
.. math::
\text{dst} (x, y) = \text{src} \left(
\frac{M^{-1}_{11} x + M^{-1}_{12} y + M^{-1}_{13}}{M^{-1}_{31} x + M^{-1}_{32} y + M^{-1}_{33}} ,
\frac{M^{-1}_{21} x + M^{-1}_{22} y + M^{-1}_{23}}{M^{-1}_{31} x + M^{-1}_{32} y + M^{-1}_{33}}
\right )
Args:
src: input image with shape :math:`(B, C, H, W)`.
M: transformation matrix with shape :math:`(B, 3, 3)`.
dsize: size of the output image (height, width).
mode: interpolation mode to calculate output values ``'bilinear'`` | ``'nearest'``.
padding_mode: padding mode for outside grid values ``'zeros'`` | ``'border'`` | ``'reflection'``.
align_corners(bool, optional): interpolation flag.
Returns:
the warped input image :math:`(B, C, H, W)`.
Example:
>>> img = torch.rand(1, 4, 5, 6)
>>> H = torch.eye(3)[None]
>>> out = warp_perspective(img, H, (4, 2), align_corners=True)
>>> print(out.shape)
torch.Size([1, 4, 4, 2])
.. note::
This function is often used in conjuntion with :func:`get_perspective_transform`.
.. note::
See a working example `here <https://kornia-tutorials.readthedocs.io/en/
latest/warp_perspective.html>`_.
"""
if not isinstance(src, torch.Tensor):
raise TypeError("Input src type is not a torch.Tensor. Got {}".format(
type(src)))
if not isinstance(M, torch.Tensor):
raise TypeError("Input M type is not a torch.Tensor. Got {}".format(
type(M)))
if not len(src.shape) == 4:
raise ValueError("Input src must be a BxCxHxW tensor. Got {}".format(
src.shape))
if not (len(M.shape) == 3 and M.shape[-2:] == (3, 3)):
raise ValueError("Input M must be a Bx3x3 tensor. Got {}".format(
M.shape))
# TODO: remove the statement below in kornia v0.6
if align_corners is None:
message: str = (
"The align_corners default value has been changed. By default now is set True "
"in order to match cv2.warpPerspective. In case you want to keep your previous "
"behaviour set it to False. This warning will disappear in kornia > v0.6."
)
warnings.warn(message)
# set default value for align corners
align_corners = True
B, C, H, W = src.size()
h_out, w_out = dsize
# we normalize the 3x3 transformation matrix and convert to 3x4
dst_norm_trans_src_norm: torch.Tensor = normalize_homography(
M, (H, W), (h_out, w_out)) # Bx3x3
src_norm_trans_dst_norm = _torch_inverse_cast(
dst_norm_trans_src_norm) # Bx3x3
# this piece of code substitutes F.affine_grid since it does not support 3x3
grid = (create_meshgrid(h_out,
w_out,
normalized_coordinates=True,
device=src.device).to(src.dtype).repeat(
B, 1, 1, 1))
grid = transform_points(src_norm_trans_dst_norm[:, None, None], grid)
return F.grid_sample(src,
grid,
align_corners=align_corners,
mode=mode,
padding_mode=padding_mode)
def warp_affine(
src: torch.Tensor,
M: torch.Tensor,
dsize: Tuple[int, int],
mode: str = 'bilinear',
padding_mode: str = 'zeros',
align_corners: Optional[bool] = None,
) -> torch.Tensor:
r"""Applies an affine transformation to a tensor.
.. image:: _static/img/warp_affine.png
The function warp_affine transforms the source tensor using
the specified matrix:
.. math::
\text{dst}(x, y) = \text{src} \left( M_{11} x + M_{12} y + M_{13} ,
M_{21} x + M_{22} y + M_{23} \right )
Args:
src: input tensor of shape :math:`(B, C, H, W)`.
M: affine transformation of shape :math:`(B, 2, 3)`.
dsize: size of the output image (height, width).
mode: interpolation mode to calculate output values ``'bilinear'`` | ``'nearest'``.
padding_mode (str): padding mode for outside grid values ``'zeros'`` | ``'border'`` | ``'reflection'``.
align_corners : mode for grid_generation.
Returns:
the warped tensor with shape :math:`(B, C, H, W)`.
Example:
>>> img = torch.rand(1, 4, 5, 6)
>>> A = torch.eye(2, 3)[None]
>>> out = warp_affine(img, A, (4, 2), align_corners=True)
>>> print(out.shape)
torch.Size([1, 4, 4, 2])
.. note::
This function is often used in conjuntion with :func:`get_rotation_matrix2d`,
:func:`get_shear_matrix2d`, :func:`get_affine_matrix2d`, :func:`invert_affine_transform`.
.. note::
See a working example `here <https://kornia.readthedocs.io/en/latest/
tutorials/warp_affine.html>`__.
"""
if not isinstance(src, torch.Tensor):
raise TypeError("Input src type is not a torch.Tensor. Got {}".format(
type(src)))
if not isinstance(M, torch.Tensor):
raise TypeError("Input M type is not a torch.Tensor. Got {}".format(
type(M)))
if not len(src.shape) == 4:
raise ValueError("Input src must be a BxCxHxW tensor. Got {}".format(
src.shape))
if not (len(M.shape) == 3 or M.shape[-2:] == (2, 3)):
raise ValueError("Input M must be a Bx2x3 tensor. Got {}".format(
M.shape))
# TODO: remove the statement below in kornia v0.6
if align_corners is None:
message: str = (
"The align_corners default value has been changed. By default now is set True "
"in order to match cv2.warpAffine. In case you want to keep your previous "
"behaviour set it to False. This warning will disappear in kornia > v0.6."
)
warnings.warn(message)
# set default value for align corners
align_corners = True
B, C, H, W = src.size()
# we generate a 3x3 transformation matrix from 2x3 affine
M_3x3: torch.Tensor = convert_affinematrix_to_homography(M)
dst_norm_trans_src_norm: torch.Tensor = normalize_homography(
M_3x3, (H, W), dsize)
# src_norm_trans_dst_norm = torch.inverse(dst_norm_trans_src_norm)
src_norm_trans_dst_norm = _torch_inverse_cast(dst_norm_trans_src_norm)
grid = F.affine_grid(src_norm_trans_dst_norm[:, :2, :],
[B, C, dsize[0], dsize[1]],
align_corners=align_corners)
return F.grid_sample(src,
grid,
align_corners=align_corners,
mode=mode,
padding_mode=padding_mode)
def warp_affine(
src: torch.Tensor,
M: torch.Tensor,
dsize: Tuple[int, int],
mode: str = 'bilinear',
padding_mode: str = 'zeros',
align_corners: bool = True,
) -> torch.Tensor:
r"""Apply an affine transformation to a tensor.
.. image:: _static/img/warp_affine.png
The function warp_affine transforms the source tensor using
the specified matrix:
.. math::
\text{dst}(x, y) = \text{src} \left( M_{11} x + M_{12} y + M_{13} ,
M_{21} x + M_{22} y + M_{23} \right )
Args:
src: input tensor of shape :math:`(B, C, H, W)`.
M: affine transformation of shape :math:`(B, 2, 3)`.
dsize: size of the output image (height, width).
mode: interpolation mode to calculate output values ``'bilinear'`` | ``'nearest'``.
padding_mode (str): padding mode for outside grid values ``'zeros'`` | ``'border'`` | ``'reflection'``.
align_corners : mode for grid_generation.
Returns:
the warped tensor with shape :math:`(B, C, H, W)`.
.. note::
This function is often used in conjunction with :func:`get_rotation_matrix2d`,
:func:`get_shear_matrix2d`, :func:`get_affine_matrix2d`, :func:`invert_affine_transform`.
.. note::
See a working example `here <https://kornia-tutorials.readthedocs.io/en/latest/
rotate_affine.html>`__.
Example:
>>> img = torch.rand(1, 4, 5, 6)
>>> A = torch.eye(2, 3)[None]
>>> out = warp_affine(img, A, (4, 2), align_corners=True)
>>> print(out.shape)
torch.Size([1, 4, 4, 2])
"""
if not isinstance(src, torch.Tensor):
raise TypeError(f"Input src type is not a torch.Tensor. Got {type(src)}")
if not isinstance(M, torch.Tensor):
raise TypeError(f"Input M type is not a torch.Tensor. Got {type(M)}")
if not len(src.shape) == 4:
raise ValueError(f"Input src must be a BxCxHxW tensor. Got {src.shape}")
if not (len(M.shape) == 3 or M.shape[-2:] == (2, 3)):
raise ValueError(f"Input M must be a Bx2x3 tensor. Got {M.shape}")
B, C, H, W = src.size()
# we generate a 3x3 transformation matrix from 2x3 affine
M_3x3: torch.Tensor = convert_affinematrix_to_homography(M)
dst_norm_trans_src_norm: torch.Tensor = normalize_homography(M_3x3, (H, W), dsize)
# src_norm_trans_dst_norm = torch.inverse(dst_norm_trans_src_norm)
src_norm_trans_dst_norm = _torch_inverse_cast(dst_norm_trans_src_norm)
grid = F.affine_grid(src_norm_trans_dst_norm[:, :2, :], [B, C, dsize[0], dsize[1]], align_corners=align_corners)
return F.grid_sample(src, grid, align_corners=align_corners, mode=mode, padding_mode=padding_mode)
def warp_affine3d(
src: torch.Tensor,
M: torch.Tensor,
dsize: Tuple[int, int, int],
flags: str = 'bilinear',
padding_mode: str = 'zeros',
align_corners: Optional[bool] = None,
) -> torch.Tensor:
r"""Applies a projective transformation a to 3d tensor.
.. warning::
This API signature it is experimental and might suffer some changes in the future.
Args:
src : input tensor of shape :math:`(B, C, D, H, W)`.
M: projective transformation matrix of shape :math:`(B, 3, 4)`.
dsize: size of the output image (depth, height, width).
mode: interpolation mode to calculate output values
``'bilinear'`` | ``'nearest'``.
padding_mode: padding mode for outside grid values
``'zeros'`` | ``'border'`` | ``'reflection'``.
align_corners : mode for grid_generation.
Returns:
torch.Tensor: the warped 3d tensor with shape :math:`(B, C, D, H, W)`.
.. note::
This function is often used in conjuntion with :func:`get_perspective_transform3d`.
"""
assert len(src.shape) == 5, src.shape
assert len(M.shape) == 3 and M.shape[-2:] == (3, 4), M.shape
assert len(dsize) == 3, dsize
B, C, D, H, W = src.size()
# TODO: remove the statement below in kornia v0.6
if align_corners is None:
message: str = (
"The align_corners default value has been changed. By default now is set True "
"in order to match cv2.warpAffine. In case you want to keep your previous "
"behaviour set it to False. This warning will disappear in kornia > v0.6."
)
warnings.warn(message)
# set default value for align corners
align_corners = True
size_src: Tuple[int, int, int] = (D, H, W)
size_out: Tuple[int, int, int] = dsize
M_4x4 = convert_affinematrix_to_homography3d(M) # Bx4x4
# we need to normalize the transformation since grid sample needs -1/1 coordinates
dst_norm_trans_src_norm: torch.Tensor = normalize_homography3d(
M_4x4, size_src, size_out) # Bx4x4
src_norm_trans_dst_norm = _torch_inverse_cast(dst_norm_trans_src_norm)
P_norm: torch.Tensor = src_norm_trans_dst_norm[:, :3] # Bx3x4
# compute meshgrid and apply to input
dsize_out: List[int] = [B, C] + list(size_out)
grid = torch.nn.functional.affine_grid(P_norm,
dsize_out,
align_corners=align_corners)
return torch.nn.functional.grid_sample(src,
grid,
align_corners=align_corners,
mode=flags,
padding_mode=padding_mode)
def _get_inverse_transformation(cls,
transform: torch.Tensor) -> torch.Tensor:
return _torch_inverse_cast(transform)
