Source code for kornia.geometry.camera.perspective

import torch
import torch.nn.functional as F

from kornia.geometry.conversions import (
    convert_points_from_homogeneous,
    convert_points_to_homogeneous,
    denormalize_points_with_intrinsics,
    normalize_points_with_intrinsics,
)


[docs]def project_points(point_3d: torch.Tensor, camera_matrix: torch.Tensor) -> torch.Tensor: r"""Project a 3d point onto the 2d camera plane. Args: point3d: tensor containing the 3d points to be projected to the camera plane. The shape of the tensor can be :math:`(*, 3)`. camera_matrix: tensor containing the intrinsics camera matrix. The tensor shape must be :math:`(*, 3, 3)`. Returns: tensor of (u, v) cam coordinates with shape :math:`(*, 2)`. Example: >>> _ = torch.manual_seed(0) >>> X = torch.rand(1, 3) >>> K = torch.eye(3)[None] >>> project_points(X, K) tensor([[5.6088, 8.6827]]) """ # projection eq. [u, v, w]' = K * [x y z 1]' # u = fx * X / Z + cx # v = fy * Y / Z + cy # project back using depth dividing in a safe way xy_coords: torch.Tensor = convert_points_from_homogeneous(point_3d) return denormalize_points_with_intrinsics(xy_coords, camera_matrix)
[docs]def unproject_points( point_2d: torch.Tensor, depth: torch.Tensor, camera_matrix: torch.Tensor, normalize: bool = False ) -> torch.Tensor: r"""Unproject a 2d point in 3d. Transform coordinates in the pixel frame to the camera frame. Args: point2d: tensor containing the 2d to be projected to world coordinates. The shape of the tensor can be :math:`(*, 2)`. depth: tensor containing the depth value of each 2d points. The tensor shape must be equal to point2d :math:`(*, 1)`. camera_matrix: tensor containing the intrinsics camera matrix. The tensor shape must be :math:`(*, 3, 3)`. normalize: whether to normalize the pointcloud. This must be set to `True` when the depth is represented as the Euclidean ray length from the camera position. Returns: tensor of (x, y, z) world coordinates with shape :math:`(*, 3)`. Example: >>> _ = torch.manual_seed(0) >>> x = torch.rand(1, 2) >>> depth = torch.ones(1, 1) >>> K = torch.eye(3)[None] >>> unproject_points(x, depth, K) tensor([[0.4963, 0.7682, 1.0000]]) """ if not isinstance(depth, torch.Tensor): raise TypeError(f"Input depth type is not a torch.Tensor. Got {type(depth)}") if not depth.shape[-1] == 1: raise ValueError("Input depth must be in the shape of (*, 1)." " Got {}".format(depth.shape)) xy: torch.Tensor = normalize_points_with_intrinsics(point_2d, camera_matrix) xyz: torch.Tensor = convert_points_to_homogeneous(xy) if normalize: xyz = F.normalize(xyz, dim=-1, p=2.0) return xyz * depth