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# Copyright 2023 Open AI and The HuggingFace 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.
from dataclasses import dataclass
from typing import Tuple
import numpy as np
import torch
@dataclass
class DifferentiableProjectiveCamera:
"""
Implements a batch, differentiable, standard pinhole camera
"""
origin: torch.Tensor # [batch_size x 3]
x: torch.Tensor # [batch_size x 3]
y: torch.Tensor # [batch_size x 3]
z: torch.Tensor # [batch_size x 3]
width: int
height: int
x_fov: float
y_fov: float
shape: Tuple[int]
def __post_init__(self):
assert self.x.shape[0] == self.y.shape[0] == self.z.shape[0] == self.origin.shape[0]
assert self.x.shape[1] == self.y.shape[1] == self.z.shape[1] == self.origin.shape[1] == 3
assert len(self.x.shape) == len(self.y.shape) == len(self.z.shape) == len(self.origin.shape) == 2
def resolution(self):
return torch.from_numpy(np.array([self.width, self.height], dtype=np.float32))
def fov(self):
return torch.from_numpy(np.array([self.x_fov, self.y_fov], dtype=np.float32))
def get_image_coords(self) -> torch.Tensor:
"""
:return: coords of shape (width * height, 2)
"""
pixel_indices = torch.arange(self.height * self.width)
coords = torch.stack(
[
pixel_indices % self.width,
torch.div(pixel_indices, self.width, rounding_mode="trunc"),
],
axis=1,
)
return coords
@property
def camera_rays(self):
batch_size, *inner_shape = self.shape
inner_batch_size = int(np.prod(inner_shape))
coords = self.get_image_coords()
coords = torch.broadcast_to(coords.unsqueeze(0), [batch_size * inner_batch_size, *coords.shape])
rays = self.get_camera_rays(coords)
rays = rays.view(batch_size, inner_batch_size * self.height * self.width, 2, 3)
return rays
def get_camera_rays(self, coords: torch.Tensor) -> torch.Tensor:
batch_size, *shape, n_coords = coords.shape
assert n_coords == 2
assert batch_size == self.origin.shape[0]
flat = coords.view(batch_size, -1, 2)
res = self.resolution()
fov = self.fov()
fracs = (flat.float() / (res - 1)) * 2 - 1
fracs = fracs * torch.tan(fov / 2)
fracs = fracs.view(batch_size, -1, 2)
directions = (
self.z.view(batch_size, 1, 3)
+ self.x.view(batch_size, 1, 3) * fracs[:, :, :1]
+ self.y.view(batch_size, 1, 3) * fracs[:, :, 1:]
)
directions = directions / directions.norm(dim=-1, keepdim=True)
rays = torch.stack(
[
torch.broadcast_to(self.origin.view(batch_size, 1, 3), [batch_size, directions.shape[1], 3]),
directions,
],
dim=2,
)
return rays.view(batch_size, *shape, 2, 3)
def resize_image(self, width: int, height: int) -> "DifferentiableProjectiveCamera":
"""
Creates a new camera for the resized view assuming the aspect ratio does not change.
"""
assert width * self.height == height * self.width, "The aspect ratio should not change."
return DifferentiableProjectiveCamera(
origin=self.origin,
x=self.x,
y=self.y,
z=self.z,
width=width,
height=height,
x_fov=self.x_fov,
y_fov=self.y_fov,
)
def create_pan_cameras(size: int) -> DifferentiableProjectiveCamera:
origins = []
xs = []
ys = []
zs = []
for theta in np.linspace(0, 2 * np.pi, num=20):
z = np.array([np.sin(theta), np.cos(theta), -0.5])
z /= np.sqrt(np.sum(z**2))
origin = -z * 4
x = np.array([np.cos(theta), -np.sin(theta), 0.0])
y = np.cross(z, x)
origins.append(origin)
xs.append(x)
ys.append(y)
zs.append(z)
return DifferentiableProjectiveCamera(
origin=torch.from_numpy(np.stack(origins, axis=0)).float(),
x=torch.from_numpy(np.stack(xs, axis=0)).float(),
y=torch.from_numpy(np.stack(ys, axis=0)).float(),
z=torch.from_numpy(np.stack(zs, axis=0)).float(),
width=size,
height=size,
x_fov=0.7,
y_fov=0.7,
shape=(1, len(xs)),
)
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