first commit

This commit is contained in:
LinZhuoChen
2026-04-16 09:51:30 +08:00
commit f9b3ae457a
44 changed files with 11994 additions and 0 deletions

View File

@@ -0,0 +1,774 @@
# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
import os
import torch
import numpy as np
from scipy.spatial.transform import Rotation as R
from scipy.spatial.transform import Rotation
try:
from lietorch import SE3, Sim3
except ImportError:
SE3 = Sim3 = None
import torch.nn.functional as F
try:
from lingbot_map.dependency.distortion import apply_distortion, iterative_undistortion, single_undistortion
except ImportError:
apply_distortion = iterative_undistortion = single_undistortion = None
def unproject_depth_map_to_point_map(
depth_map: np.ndarray, extrinsics_cam: np.ndarray, intrinsics_cam: np.ndarray
) -> np.ndarray:
"""
Unproject a batch of depth maps to 3D world coordinates.
Args:
depth_map (np.ndarray): Batch of depth maps of shape (S, H, W, 1) or (S, H, W)
extrinsics_cam (np.ndarray): Batch of camera extrinsic matrices of shape (S, 3, 4)
intrinsics_cam (np.ndarray): Batch of camera intrinsic matrices of shape (S, 3, 3)
Returns:
np.ndarray: Batch of 3D world coordinates of shape (S, H, W, 3)
"""
if isinstance(depth_map, torch.Tensor):
depth_map = depth_map.cpu().numpy()
if isinstance(extrinsics_cam, torch.Tensor):
extrinsics_cam = extrinsics_cam.cpu().numpy()
if isinstance(intrinsics_cam, torch.Tensor):
intrinsics_cam = intrinsics_cam.cpu().numpy()
world_points_list = []
for frame_idx in range(depth_map.shape[0]):
cur_world_points, _, _ = depth_to_world_coords_points(
depth_map[frame_idx].squeeze(-1), extrinsics_cam[frame_idx], intrinsics_cam[frame_idx]
)
world_points_list.append(cur_world_points)
world_points_array = np.stack(world_points_list, axis=0)
return world_points_array
def depth_to_world_coords_points(
depth_map: np.ndarray,
extrinsic: np.ndarray,
intrinsic: np.ndarray,
eps=1e-8,
) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
"""
Convert a depth map to world coordinates.
Args:
depth_map (np.ndarray): Depth map of shape (H, W).
intrinsic (np.ndarray): Camera intrinsic matrix of shape (3, 3).
extrinsic (np.ndarray): Camera extrinsic matrix of shape (3, 4). OpenCV camera coordinate convention, cam from world.
Returns:
tuple[np.ndarray, np.ndarray]: World coordinates (H, W, 3) and valid depth mask (H, W).
"""
if depth_map is None:
return None, None, None
# Valid depth mask
point_mask = depth_map > eps
# Convert depth map to camera coordinates
cam_coords_points = depth_to_cam_coords_points(depth_map, intrinsic)
# Multiply with the inverse of extrinsic matrix to transform to world coordinates
# extrinsic_inv is 4x4 (note closed_form_inverse_OpenCV is batched, the output is (N, 4, 4))
cam_to_world_extrinsic = closed_form_inverse_se3(extrinsic[None])[0]
R_cam_to_world = cam_to_world_extrinsic[:3, :3]
t_cam_to_world = cam_to_world_extrinsic[:3, 3]
# Apply the rotation and translation to the camera coordinates
world_coords_points = np.dot(cam_coords_points, R_cam_to_world.T) + t_cam_to_world # HxWx3, 3x3 -> HxWx3
# world_coords_points = np.einsum("ij,hwj->hwi", R_cam_to_world, cam_coords_points) + t_cam_to_world
return world_coords_points, cam_coords_points, point_mask
def depth_to_cam_coords_points(depth_map: np.ndarray, intrinsic: np.ndarray) -> tuple[np.ndarray, np.ndarray]:
"""
Convert a depth map to camera coordinates.
Args:
depth_map (np.ndarray): Depth map of shape (H, W).
intrinsic (np.ndarray): Camera intrinsic matrix of shape (3, 3).
Returns:
tuple[np.ndarray, np.ndarray]: Camera coordinates (H, W, 3)
"""
H, W = depth_map.shape
assert intrinsic.shape == (3, 3), "Intrinsic matrix must be 3x3"
assert intrinsic[0, 1] == 0 and intrinsic[1, 0] == 0, "Intrinsic matrix must have zero skew"
# Intrinsic parameters
fu, fv = intrinsic[0, 0], intrinsic[1, 1]
cu, cv = intrinsic[0, 2], intrinsic[1, 2]
# Generate grid of pixel coordinates
u, v = np.meshgrid(np.arange(W), np.arange(H))
# Unproject to camera coordinates
x_cam = (u - cu) * depth_map / fu
y_cam = (v - cv) * depth_map / fv
z_cam = depth_map
# Stack to form camera coordinates
cam_coords = np.stack((x_cam, y_cam, z_cam), axis=-1).astype(np.float32)
return cam_coords
def closed_form_inverse_se3(se3, R=None, T=None):
"""
Compute the inverse of each 4x4 (or 3x4) SE3 matrix in a batch.
If `R` and `T` are provided, they must correspond to the rotation and translation
components of `se3`. Otherwise, they will be extracted from `se3`.
Args:
se3: Nx4x4 or Nx3x4 array or tensor of SE3 matrices.
R (optional): Nx3x3 array or tensor of rotation matrices.
T (optional): Nx3x1 array or tensor of translation vectors.
Returns:
Inverted SE3 matrices with the same type and device as `se3`.
Shapes:
se3: (N, 4, 4)
R: (N, 3, 3)
T: (N, 3, 1)
"""
# Check if se3 is a numpy array or a torch tensor
is_numpy = isinstance(se3, np.ndarray)
# Validate shapes
if se3.shape[-2:] != (4, 4) and se3.shape[-2:] != (3, 4):
raise ValueError(f"se3 must be of shape (N,4,4), got {se3.shape}.")
# Extract R and T if not provided
if R is None:
R = se3[:, :3, :3] # (N,3,3)
if T is None:
T = se3[:, :3, 3:] # (N,3,1)
# Transpose R
if is_numpy:
# Compute the transpose of the rotation for NumPy
R_transposed = np.transpose(R, (0, 2, 1))
# -R^T t for NumPy
top_right = -np.matmul(R_transposed, T)
inverted_matrix = np.tile(np.eye(4), (len(R), 1, 1))
else:
R_transposed = R.transpose(1, 2) # (N,3,3)
top_right = -torch.bmm(R_transposed, T) # (N,3,1)
inverted_matrix = torch.eye(4, 4)[None].repeat(len(R), 1, 1)
inverted_matrix = inverted_matrix.to(R.dtype).to(R.device)
inverted_matrix[:, :3, :3] = R_transposed
inverted_matrix[:, :3, 3:] = top_right
return inverted_matrix
def closed_form_inverse_se3_general(se3, R=None, T=None):
"""
支持任意 batch 维度的 SE3 逆运算
se3: (..., 4, 4) 或 (..., 3, 4)
"""
batch_shape = se3.shape[:-2]
if R is None:
R = se3[..., :3, :3]
if T is None:
T = se3[..., :3, 3:]
R_transposed = R.transpose(-2, -1)
top_right = -R_transposed @ T
# 构造单位阵
eye = torch.eye(4, 4, dtype=R.dtype, device=R.device)
inverted_matrix = eye.expand(*batch_shape, 4, 4).clone()
inverted_matrix[..., :3, :3] = R_transposed
inverted_matrix[..., :3, 3:] = top_right
return inverted_matrix
# TODO: this code can be further cleaned up
def project_world_points_to_camera_points_batch(world_points, cam_extrinsics):
"""
Transforms 3D points to 2D using extrinsic and intrinsic parameters.
Args:
world_points (torch.Tensor): 3D points of shape BxSxHxWx3.
cam_extrinsics (torch.Tensor): Extrinsic parameters of shape BxSx3x4.
Returns:
"""
# TODO: merge this into project_world_points_to_cam
# device = world_points.device
# with torch.autocast(device_type=device.type, enabled=False):
ones = torch.ones_like(world_points[..., :1]) # shape: (B, S, H, W, 1)
world_points_h = torch.cat([world_points, ones], dim=-1) # shape: (B, S, H, W, 4)
# extrinsics: (B, S, 3, 4) -> (B, S, 1, 1, 3, 4)
extrinsics_exp = cam_extrinsics.unsqueeze(2).unsqueeze(3)
# world_points_h: (B, S, H, W, 4) -> (B, S, H, W, 4, 1)
world_points_h_exp = world_points_h.unsqueeze(-1)
# Now perform the matrix multiplication
# (B, S, 1, 1, 3, 4) @ (B, S, H, W, 4, 1) broadcasts to (B, S, H, W, 3, 1)
camera_points = torch.matmul(extrinsics_exp, world_points_h_exp).squeeze(-1)
return camera_points
def project_world_points_to_cam(
world_points,
cam_extrinsics,
cam_intrinsics=None,
distortion_params=None,
default=0,
only_points_cam=False,
):
"""
Transforms 3D points to 2D using extrinsic and intrinsic parameters.
Args:
world_points (torch.Tensor): 3D points of shape Px3.
cam_extrinsics (torch.Tensor): Extrinsic parameters of shape Bx3x4.
cam_intrinsics (torch.Tensor): Intrinsic parameters of shape Bx3x3.
distortion_params (torch.Tensor): Extra parameters of shape BxN, which is used for radial distortion.
Returns:
torch.Tensor: Transformed 2D points of shape BxNx2.
"""
device = world_points.device
# with torch.autocast(device_type=device.type, dtype=torch.double):
with torch.autocast(device_type=device.type, enabled=False):
N = world_points.shape[0] # Number of points
B = cam_extrinsics.shape[0] # Batch size, i.e., number of cameras
world_points_homogeneous = torch.cat(
[world_points, torch.ones_like(world_points[..., 0:1])], dim=1
) # Nx4
# Reshape for batch processing
world_points_homogeneous = world_points_homogeneous.unsqueeze(0).expand(
B, -1, -1
) # BxNx4
# Step 1: Apply extrinsic parameters
# Transform 3D points to camera coordinate system for all cameras
cam_points = torch.bmm(
cam_extrinsics, world_points_homogeneous.transpose(-1, -2)
)
if only_points_cam:
return None, cam_points
# Step 2: Apply intrinsic parameters and (optional) distortion
image_points = img_from_cam(cam_intrinsics, cam_points, distortion_params, default=default)
return image_points, cam_points
def img_from_cam(cam_intrinsics, cam_points, distortion_params=None, default=0.0):
"""
Applies intrinsic parameters and optional distortion to the given 3D points.
Args:
cam_intrinsics (torch.Tensor): Intrinsic camera parameters of shape Bx3x3.
cam_points (torch.Tensor): 3D points in camera coordinates of shape Bx3xN.
distortion_params (torch.Tensor, optional): Distortion parameters of shape BxN, where N can be 1, 2, or 4.
default (float, optional): Default value to replace NaNs in the output.
Returns:
pixel_coords (torch.Tensor): 2D points in pixel coordinates of shape BxNx2.
"""
# Normalized device coordinates (NDC)
cam_points = cam_points / cam_points[:, 2:3, :]
ndc_xy = cam_points[:, :2, :]
# Apply distortion if distortion_params are provided
if distortion_params is not None:
x_distorted, y_distorted = apply_distortion(distortion_params, ndc_xy[:, 0], ndc_xy[:, 1])
distorted_xy = torch.stack([x_distorted, y_distorted], dim=1)
else:
distorted_xy = ndc_xy
# Prepare cam_points for batch matrix multiplication
cam_coords_homo = torch.cat(
(distorted_xy, torch.ones_like(distorted_xy[:, :1, :])), dim=1
) # Bx3xN
# Apply intrinsic parameters using batch matrix multiplication
pixel_coords = torch.bmm(cam_intrinsics, cam_coords_homo) # Bx3xN
# Extract x and y coordinates
pixel_coords = pixel_coords[:, :2, :] # Bx2xN
# Replace NaNs with default value
pixel_coords = torch.nan_to_num(pixel_coords, nan=default)
return pixel_coords.transpose(1, 2) # BxNx2
def cam_from_img(pred_tracks, intrinsics, extra_params=None):
"""
Normalize predicted tracks based on camera intrinsics.
Args:
intrinsics (torch.Tensor): The camera intrinsics tensor of shape [batch_size, 3, 3].
pred_tracks (torch.Tensor): The predicted tracks tensor of shape [batch_size, num_tracks, 2].
extra_params (torch.Tensor, optional): Distortion parameters of shape BxN, where N can be 1, 2, or 4.
Returns:
torch.Tensor: Normalized tracks tensor.
"""
# We don't want to do intrinsics_inv = torch.inverse(intrinsics) here
# otherwise we can use something like
# tracks_normalized_homo = torch.bmm(pred_tracks_homo, intrinsics_inv.transpose(1, 2))
principal_point = intrinsics[:, [0, 1], [2, 2]].unsqueeze(-2)
focal_length = intrinsics[:, [0, 1], [0, 1]].unsqueeze(-2)
tracks_normalized = (pred_tracks - principal_point) / focal_length
if extra_params is not None:
# Apply iterative undistortion
try:
tracks_normalized = iterative_undistortion(
extra_params, tracks_normalized
)
except:
tracks_normalized = single_undistortion(
extra_params, tracks_normalized
)
return tracks_normalized
## Droid SLAM Part
MIN_DEPTH = 0.2
def extract_intrinsics(intrinsics):
return intrinsics[...,None,None,:].unbind(dim=-1)
def projective_transform(
poses, depths, intrinsics, ii, jj, jacobian=False, return_depth=False
):
"""map points from ii->jj"""
# inverse project (pinhole)
X0, Jz = iproj(depths[:, ii], intrinsics[:, ii], jacobian=jacobian)
# transform
Gij = poses[:, jj] * poses[:, ii].inv()
# Gij.data[:, ii == jj] = torch.as_tensor(
# [-0.1, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0], device="cuda"
# )
X1, Ja = actp(Gij, X0, jacobian=jacobian)
# project (pinhole)
x1, Jp = proj(X1, intrinsics[:, jj], jacobian=jacobian, return_depth=return_depth)
# exclude points too close to camera
valid = ((X1[..., 2] > MIN_DEPTH) & (X0[..., 2] > MIN_DEPTH)).float()
valid = valid.unsqueeze(-1)
if jacobian:
# Ji transforms according to dual adjoint
Jj = torch.matmul(Jp, Ja)
Ji = -Gij[:, :, None, None, None].adjT(Jj)
Jz = Gij[:, :, None, None] * Jz
Jz = torch.matmul(Jp, Jz.unsqueeze(-1))
return x1, valid, (Ji, Jj, Jz)
return x1, valid
def induced_flow(poses, disps, intrinsics, ii, jj):
"""optical flow induced by camera motion"""
ht, wd = disps.shape[2:]
y, x = torch.meshgrid(
torch.arange(ht, device=disps.device, dtype=torch.float),
torch.arange(wd, device=disps.device, dtype=torch.float),
indexing="ij",
)
coords0 = torch.stack([x, y], dim=-1)
coords1, valid = projective_transform(poses, disps, intrinsics, ii, jj, False)
return coords1[..., :2] - coords0, valid
def all_pairs_distance_matrix(poses, beta=2.5):
""" compute distance matrix between all pairs of poses """
poses = np.array(poses, dtype=np.float32)
poses[:,:3] *= beta # scale to balence rot + trans
poses = SE3(torch.from_numpy(poses))
r = (poses[:,None].inv() * poses[None,:]).log()
return r.norm(dim=-1).cpu().numpy()
def pose_matrix_to_quaternion(pose):
""" convert 4x4 pose matrix to (t, q) """
q = Rotation.from_matrix(pose[..., :3, :3]).as_quat()
return np.concatenate([pose[..., :3, 3], q], axis=-1)
def compute_distance_matrix_flow(poses, disps, intrinsics):
""" compute flow magnitude between all pairs of frames """
if not isinstance(poses, SE3):
poses = torch.from_numpy(poses).float().cuda()[None]
poses = SE3(poses).inv()
disps = torch.from_numpy(disps).float().cuda()[None]
intrinsics = torch.from_numpy(intrinsics).float().cuda()[None]
N = poses.shape[1]
ii, jj = torch.meshgrid(torch.arange(N), torch.arange(N))
ii = ii.reshape(-1).cuda()
jj = jj.reshape(-1).cuda()
MAX_FLOW = 100.0
matrix = np.zeros((N, N), dtype=np.float32)
s = 2048
for i in range(0, ii.shape[0], s):
flow1, val1 = induced_flow(poses, disps, intrinsics, ii[i:i+s], jj[i:i+s])
flow2, val2 = induced_flow(poses, disps, intrinsics, jj[i:i+s], ii[i:i+s])
flow = torch.stack([flow1, flow2], dim=2)
val = torch.stack([val1, val2], dim=2)
mag = flow.norm(dim=-1).clamp(max=MAX_FLOW)
mag = mag.view(mag.shape[1], -1)
val = val.view(val.shape[1], -1)
mag = (mag * val).mean(-1) / val.mean(-1)
mag[val.mean(-1) < 0.7] = np.inf
i1 = ii[i:i+s].cpu().numpy()
j1 = jj[i:i+s].cpu().numpy()
matrix[i1, j1] = mag.cpu().numpy()
return matrix
def compute_distance_matrix_flow2(poses, disps, intrinsics, beta=0.4):
""" compute flow magnitude between all pairs of frames """
# if not isinstance(poses, SE3):
# poses = torch.from_numpy(poses).float().cuda()[None]
# poses = SE3(poses).inv()
# disps = torch.from_numpy(disps).float().cuda()[None]
# intrinsics = torch.from_numpy(intrinsics).float().cuda()[None]
N = poses.shape[1]
ii, jj = torch.meshgrid(torch.arange(N), torch.arange(N))
ii = ii.reshape(-1)
jj = jj.reshape(-1)
MAX_FLOW = 128.0
matrix = np.zeros((N, N), dtype=np.float32)
s = 2048
for i in range(0, ii.shape[0], s):
flow1a, val1a = induced_flow(poses, disps, intrinsics, ii[i:i+s], jj[i:i+s], tonly=True)
flow1b, val1b = induced_flow(poses, disps, intrinsics, ii[i:i+s], jj[i:i+s])
flow2a, val2a = induced_flow(poses, disps, intrinsics, jj[i:i+s], ii[i:i+s], tonly=True)
flow2b, val2b = induced_flow(poses, disps, intrinsics, ii[i:i+s], jj[i:i+s])
flow1 = flow1a + beta * flow1b
val1 = val1a * val2b
flow2 = flow2a + beta * flow2b
val2 = val2a * val2b
flow = torch.stack([flow1, flow2], dim=2)
val = torch.stack([val1, val2], dim=2)
mag = flow.norm(dim=-1).clamp(max=MAX_FLOW)
mag = mag.view(mag.shape[1], -1)
val = val.view(val.shape[1], -1)
mag = (mag * val).mean(-1) / val.mean(-1)
mag[val.mean(-1) < 0.8] = np.inf
i1 = ii[i:i+s].cpu().numpy()
j1 = jj[i:i+s].cpu().numpy()
matrix[i1, j1] = mag.cpu().numpy()
return matrix
def coords_grid(ht, wd, **kwargs):
y, x = torch.meshgrid(
torch.arange(ht, dtype=torch.float, **kwargs),
torch.arange(wd, dtype=torch.float, **kwargs),
indexing="ij",
)
return torch.stack([x, y], dim=-1)
def iproj(disps, intrinsics, jacobian=False):
"""pinhole camera inverse projection"""
ht, wd = disps.shape[2:]
fx, fy, cx, cy = extract_intrinsics(intrinsics)
y, x = torch.meshgrid(
torch.arange(ht, device=disps.device, dtype=torch.float),
torch.arange(wd, device=disps.device, dtype=torch.float),
indexing="ij",
)
i = torch.ones_like(disps)
X = (x - cx) / fx
Y = (y - cy) / fy
pts = torch.stack([X, Y, i, disps], dim=-1)
if jacobian:
J = torch.zeros_like(pts)
J[..., -1] = 1.0
return pts, J
return pts, None
def proj(Xs, intrinsics, jacobian=False, return_depth=False):
"""pinhole camera projection"""
fx, fy, cx, cy = extract_intrinsics(intrinsics)
X, Y, Z, D = Xs.unbind(dim=-1)
Z = torch.where(Z < 0.5 * MIN_DEPTH, torch.ones_like(Z), Z)
d = 1.0 / Z
x = fx * (X * d) + cx
y = fy * (Y * d) + cy
if return_depth:
coords = torch.stack([x, y, D * d], dim=-1)
else:
coords = torch.stack([x, y], dim=-1)
if jacobian:
B, N, H, W = d.shape
o = torch.zeros_like(d)
proj_jac = torch.stack(
[
fx * d,
o,
-fx * X * d * d,
o,
o,
fy * d,
-fy * Y * d * d,
o,
# o, o, -D*d*d, d,
],
dim=-1,
).view(B, N, H, W, 2, 4)
return coords, proj_jac
return coords, None
def actp(Gij, X0, jacobian=False):
"""action on point cloud"""
X1 = Gij[:, :, None, None] * X0
if jacobian:
X, Y, Z, d = X1.unbind(dim=-1)
o = torch.zeros_like(d)
B, N, H, W = d.shape
if isinstance(Gij, SE3):
Ja = torch.stack(
[
d,
o,
o,
o,
Z,
-Y,
o,
d,
o,
-Z,
o,
X,
o,
o,
d,
Y,
-X,
o,
o,
o,
o,
o,
o,
o,
],
dim=-1,
).view(B, N, H, W, 4, 6)
elif isinstance(Gij, Sim3):
Ja = torch.stack(
[
d,
o,
o,
o,
Z,
-Y,
X,
o,
d,
o,
-Z,
o,
X,
Y,
o,
o,
d,
Y,
-X,
o,
Z,
o,
o,
o,
o,
o,
o,
o,
],
dim=-1,
).view(B, N, H, W, 4, 7)
return X1, Ja
return X1, None
def _sqrt_positive_part(x: torch.Tensor) -> torch.Tensor:
"""
Returns torch.sqrt(torch.max(0, x))
but with a zero subgradient where x is 0.
"""
ret = torch.zeros_like(x)
positive_mask = x > 0
ret[positive_mask] = torch.sqrt(x[positive_mask])
return ret
def matrix_to_quaternion(matrix: torch.Tensor) -> torch.Tensor:
"""
Convert rotations given as rotation matrices to quaternions.
Args:
matrix: Rotation matrices as tensor of shape (..., 3, 3).
Returns:
quaternions with real part first, as tensor of shape (..., 4).
"""
if matrix.shape[-1] != 3 or matrix.shape[-2] != 3:
raise ValueError(f"Invalid rotation matrix shape {matrix.shape}.")
batch_dim = matrix.shape[:-2]
m00, m01, m02, m10, m11, m12, m20, m21, m22 = torch.unbind(
matrix.reshape(batch_dim + (9,)), dim=-1
)
q_abs = _sqrt_positive_part(
torch.stack(
[
1.0 + m00 + m11 + m22,
1.0 + m00 - m11 - m22,
1.0 - m00 + m11 - m22,
1.0 - m00 - m11 + m22,
],
dim=-1,
)
)
quat_by_rijk = torch.stack(
[
torch.stack([q_abs[..., 0] ** 2, m21 - m12, m02 - m20, m10 - m01], dim=-1),
torch.stack([m21 - m12, q_abs[..., 1] ** 2, m10 + m01, m02 + m20], dim=-1),
torch.stack([m02 - m20, m10 + m01, q_abs[..., 2] ** 2, m12 + m21], dim=-1),
torch.stack([m10 - m01, m20 + m02, m21 + m12, q_abs[..., 3] ** 2], dim=-1),
],
dim=-2,
)
flr = torch.tensor(0.1).to(dtype=q_abs.dtype, device=q_abs.device)
quat_candidates = quat_by_rijk / (2.0 * q_abs[..., None].max(flr))
out = quat_candidates[
F.one_hot(q_abs.argmax(dim=-1), num_classes=4) > 0.5, :
].reshape(batch_dim + (4,))
return standardize_quaternion(out)
def standardize_quaternion(quaternions: torch.Tensor) -> torch.Tensor:
"""
Convert a unit quaternion to a standard form: one in which the real
part is non negative.
Args:
quaternions: Quaternions with real part first,
as tensor of shape (..., 4).
Returns:
Standardized quaternions as tensor of shape (..., 4).
"""
quaternions = F.normalize(quaternions, p=2, dim=-1)
return torch.where(quaternions[..., 0:1] < 0, -quaternions, quaternions)
def umeyama(X, Y):
"""
Estimates the Sim(3) transformation between `X` and `Y` point sets.
Estimates c, R and t such as c * R @ X + t ~ Y.
Parameters
----------
X : numpy.array
(m, n) shaped numpy array. m is the dimension of the points,
n is the number of points in the point set.
Y : numpy.array
(m, n) shaped numpy array. Indexes should be consistent with `X`.
That is, Y[:, i] must be the point corresponding to X[:, i].
Returns
-------
c : float
Scale factor.
R : numpy.array
(3, 3) shaped rotation matrix.
t : numpy.array
(3, 1) shaped translation vector.
"""
mu_x = X.mean(axis=1).reshape(-1, 1)
mu_y = Y.mean(axis=1).reshape(-1, 1)
var_x = np.square(X - mu_x).sum(axis=0).mean()
cov_xy = ((Y - mu_y) @ (X - mu_x).T) / X.shape[1]
U, D, VH = np.linalg.svd(cov_xy)
S = np.eye(X.shape[0])
if np.linalg.det(U) * np.linalg.det(VH) < 0:
S[-1, -1] = -1
c = np.trace(np.diag(D) @ S) / var_x
R = U @ S @ VH
t = mu_y - c * R @ mu_x
return c, R, t