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import torch
import torch.nn.functional as F
import numpy as np
class InputPadder:
""" Pads images such that dimensions are divisible by 8 """
def __init__(self, dims, mode='sintel', padding_factor=8):
self.ht, self.wd = dims[-2:]
pad_ht = (((self.ht // padding_factor) + 1) * padding_factor - self.ht) % padding_factor
pad_wd = (((self.wd // padding_factor) + 1) * padding_factor - self.wd) % padding_factor
if mode == 'sintel':
self._pad = [pad_wd // 2, pad_wd - pad_wd // 2, pad_ht // 2, pad_ht - pad_ht // 2]
else:
self._pad = [pad_wd // 2, pad_wd - pad_wd // 2, 0, pad_ht]
def pad(self, *inputs):
return [F.pad(x, self._pad, mode='replicate') for x in inputs]
def unpad(self, x):
ht, wd = x.shape[-2:]
c = [self._pad[2], ht - self._pad[3], self._pad[0], wd - self._pad[1]]
return x[..., c[0]:c[1], c[2]:c[3]]
def bilinear_sampler(img, coords, mode='bilinear', mask=False, padding_mode='zeros'):
""" Wrapper for grid_sample, uses pixel coordinates """
if coords.size(-1) != 2: # [B, 2, H, W] -> [B, H, W, 2]
coords = coords.permute(0, 2, 3, 1)
H, W = img.shape[-2:]
# H = height if height is not None else img.shape[-2]
# W = width if width is not None else img.shape[-1]
xgrid, ygrid = coords.split([1, 1], dim=-1)
# To handle H or W equals to 1 by explicitly defining height and width
if H == 1:
assert ygrid.abs().max() < 1e-8
H = 10
if W == 1:
assert xgrid.abs().max() < 1e-8
W = 10
xgrid = 2 * xgrid / (W - 1) - 1
ygrid = 2 * ygrid / (H - 1) - 1
grid = torch.cat([xgrid, ygrid], dim=-1)
img = F.grid_sample(img, grid, mode=mode,
padding_mode=padding_mode,
align_corners=True)
if mask:
mask = (xgrid > -1) & (ygrid > -1) & (xgrid < 1) & (ygrid < 1)
return img, mask.squeeze(-1).float()
return img
def coords_grid(batch, ht, wd, normalize=False):
if normalize: # [-1, 1]
coords = torch.meshgrid(2 * torch.arange(ht) / (ht - 1) - 1,
2 * torch.arange(wd) / (wd - 1) - 1)
else:
coords = torch.meshgrid(torch.arange(ht), torch.arange(wd))
coords = torch.stack(coords[::-1], dim=0).float()
return coords[None].repeat(batch, 1, 1, 1) # [B, 2, H, W]
def coords_grid_np(h, w): # used for accumulating high speed sintel flow testdata
coords = np.meshgrid(np.arange(h, dtype=np.float32),
np.arange(w, dtype=np.float32), indexing='ij')
coords = np.stack(coords[::-1], axis=-1) # [H, W, 2]
return coords
def compute_out_of_boundary_mask(flow, downsample_factor=None):
# flow: [B, 2, H, W]
assert flow.dim() == 4 and flow.size(1) == 2
b, _, h, w = flow.shape
init_coords = coords_grid(b, h, w).to(flow.device)
corres = init_coords + flow # [B, 2, H, W]
if downsample_factor is not None:
assert w % downsample_factor == 0 and h % downsample_factor == 0
# the actual max disp can predict is in the downsampled feature resolution, then upsample
max_w = (w // downsample_factor - 1) * downsample_factor
max_h = (h // downsample_factor - 1) * downsample_factor
# print('max_w: %d, max_h: %d' % (max_w, max_h))
else:
max_w = w - 1
max_h = h - 1
valid_mask = (corres[:, 0] >= 0) & (corres[:, 0] <= max_w) & (corres[:, 1] >= 0) & (corres[:, 1] <= max_h)
# in case very large flow
flow_mask = (flow[:, 0].abs() <= max_w) & (flow[:, 1].abs() <= max_h)
valid_mask = valid_mask & flow_mask
return valid_mask # [B, H, W]
def normalize_coords(grid):
"""Normalize coordinates of image scale to [-1, 1]
Args:
grid: [B, 2, H, W]
"""
assert grid.size(1) == 2
h, w = grid.size()[2:]
grid[:, 0, :, :] = 2 * (grid[:, 0, :, :].clone() / (w - 1)) - 1 # x: [-1, 1]
grid[:, 1, :, :] = 2 * (grid[:, 1, :, :].clone() / (h - 1)) - 1 # y: [-1, 1]
# grid = grid.permute((0, 2, 3, 1)) # [B, H, W, 2]
return grid
def flow_warp(feature, flow, mask=False, padding_mode='zeros'):
b, c, h, w = feature.size()
assert flow.size(1) == 2
grid = coords_grid(b, h, w).to(flow.device) + flow # [B, 2, H, W]
return bilinear_sampler(feature, grid, mask=mask, padding_mode=padding_mode)
def upflow8(flow, mode='bilinear'):
new_size = (8 * flow.shape[2], 8 * flow.shape[3])
return 8 * F.interpolate(flow, size=new_size, mode=mode, align_corners=True)
def bilinear_upflow(flow, scale_factor=8):
assert flow.size(1) == 2
flow = F.interpolate(flow, scale_factor=scale_factor,
mode='bilinear', align_corners=True) * scale_factor
return flow
def upsample_flow(flow, img):
if flow.size(-1) != img.size(-1):
scale_factor = img.size(-1) / flow.size(-1)
flow = F.interpolate(flow, size=img.size()[-2:],
mode='bilinear', align_corners=True) * scale_factor
return flow
def count_parameters(model):
num = sum(p.numel() for p in model.parameters() if p.requires_grad)
return num
def set_bn_eval(m):
classname = m.__class__.__name__
if classname.find('BatchNorm') != -1:
m.eval()