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nerfstudio/nerfactory/cameras/camera_paths.py
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# Copyright 2022 The Plenoptix Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Code for camera paths.
"""
import copy
from dataclasses import dataclass
from typing import List, Tuple
import torch
import nerfactory.cameras.utils as camera_utils
from nerfactory.cameras.cameras import (
Camera,
get_camera,
get_intrinsics_from_intrinsics_matrix,
)
from nerfactory.cameras.utils import get_interpolated_poses_many
@dataclass
class CameraPath:
"""A camera path."""
cameras: List[Camera]
def get_interpolated_camera_path(camera_a: Camera, camera_b: Camera, steps: int) -> CameraPath:
"""Generate a camera path between two cameras.
Args:
camera_a: The first camera.
camera_b: The second camera.
steps: The number of steps to interpolate between the two cameras.
Returns:
CameraPath: A camera path.
"""
device = camera_a.device
Ka = camera_a.get_intrinsics_matrix().cpu().numpy()
pose_a = camera_a.get_camera_to_world_h().cpu().numpy()
Kb = camera_b.get_intrinsics_matrix().cpu().numpy()
pose_b = camera_b.get_camera_to_world_h().cpu().numpy()
poses = [pose_a, pose_b]
Ks = [Ka, Kb]
poses, Ks = get_interpolated_poses_many(poses, Ks, steps_per_transition=steps)
cameras = []
for pose, K in zip(poses, Ks):
intrinsics = get_intrinsics_from_intrinsics_matrix(K).to(device).float()
# TODO: this makes cx and cy an integer, but this code should be fixed
# it was added to avoid floating point errors when rescaling and the image resolution
# being different per rendered image in a camera path
intrinsics[:2] = torch.round(intrinsics[:2])
camera_to_world = torch.from_numpy(pose[:3]).to(device).float()
camera = get_camera(intrinsics, camera_to_world, camera_index=camera_a.camera_index)
cameras.append(camera)
return CameraPath(cameras=cameras)
def get_spiral_path(
camera: Camera,
steps: int = 30,
radius: float = None,
radiuses: Tuple[float] = None,
rots: int = 2,
zrate: float = 0.5,
) -> CameraPath:
"""
Returns a list of camera in a sprial trajectory.
Args:
camera: The camera to start the spiral from.
steps: The number of cameras in the generated path.
radius: The radius of the spiral for all xyz directions.
radiuses: The list of radii for the spiral in xyz directions.
rots: The number of rotations to apply to the camera.
zrate: How much to change the z position of the camera.
Returns:
CameraPath: A spiral camera path.
"""
assert radius is not None or radiuses is not None, "Either radius or radiuses must be specified."
if radius is not None and radiuses is None:
rad = torch.tensor([radius] * 3, device=camera.device)
elif radiuses is not None and radius is None:
rad = torch.tensor(radiuses, device=camera.device)
else:
raise ValueError("Only one of radius or radiuses must be specified.")
# TODO: don't hardcode this. pass this in
up = camera.camera_to_world[:3, 2] # scene is z up
# up = camera.camera_to_world[:3, 1] # this will rotate 90 degrees
focal = min(camera.fx, camera.fy)
target = torch.tensor([0, 0, -focal], device=camera.device) # camera looking in -z direction
c2wh_global = camera.get_camera_to_world_h()
local_c2whs = []
for theta in torch.linspace(0.0, 2.0 * torch.pi * rots, steps + 1)[:-1]:
center = (
torch.tensor([torch.cos(theta), -torch.sin(theta), -torch.sin(theta * zrate)], device=camera.device) * rad
)
lookat = center - target
c2w = camera_utils.viewmatrix(lookat, up, center)
ones = torch.tensor([0, 0, 0, 1], device=c2w.device)[None]
c2wh = torch.cat([c2w, ones], dim=0)
local_c2whs.append(c2wh)
cameras = []
for local_c2wh in local_c2whs:
cam = copy.deepcopy(camera)
c2wh = torch.matmul(c2wh_global, local_c2wh)
cam.camera_to_world = c2wh[:3, :4]
cameras.append(cam)
return CameraPath(cameras=cameras)