Spaces:
Sleeping
Sleeping
File size: 4,602 Bytes
d4b77ac |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 |
import numpy as np
import torch
import torch.nn as nn
# https://zhuanlan.zhihu.com/p/112030273
def warp_optical_flow(batch_x, batch_flow):
"""
Modified from https://github.com/NVlabs/PWC-Net/blob/fc6ebf9a70a7387164df09a3a2070ba16f9c1ede/PyTorch/models/PWCNet.py # NOQA
warp an im2 back to im1, according to the optical flow
x: [B, L, C, H, W] (im2)
flo: [B, L, 2, H, W] flow
"""
B, L, C, H, W = batch_x.shape
B = B * L
x = batch_x.contiguous().view(-1, C, H, W)
flo = batch_flow.view(-1, 2, H, W)
# mesh grid
xx = torch.arange(0, W).view(1, -1).repeat(H, 1)
yy = torch.arange(0, H).view(-1, 1).repeat(1, W)
xx = xx.view(1, 1, H, W).repeat(B, 1, 1, 1)
yy = yy.view(1, 1, H, W).repeat(B, 1, 1, 1)
grid = torch.cat((xx, yy), 1).float()
if x.is_cuda:
grid = grid.cuda()
vgrid = grid + flo
# scale grid to [-1, 1]
vgrid[:, 0, :, :] = 2.0 * vgrid[:, 0, :, :] / max(W - 1, 1) - 1.0
vgrid[:, 1, :, :] = 2.0 * vgrid[:, 1, :, :] / max(H - 1, 1) - 1.0
vgrid = vgrid.permute(0, 2, 3, 1) # B, H, W, 2(compatible with API)
output = nn.functional.grid_sample(x, vgrid) # 按照vgrid将x warp到output张量上
mask = torch.autograd.Variable(torch.ones(x.size())).cuda()
mask = nn.functional.grid_sample(mask, vgrid) # 这个我觉得没有太大意义,因为warp之后还是1(mask默认全是1)
mask[mask < 0.9999] = 0
mask[mask > 0] = 1 # 仍然全是1
result = output * mask
return result.view(-1, L, C, H, W)
UNKNOWN_FLOW_THRESH = 1e7
def flow_to_image(flow):
"""
Convert flow into middlebury color code image
:param flow: optical flow map
:return: optical flow image in middlebury color
"""
u = flow[:, :, 0]
v = flow[:, :, 1]
maxu = -999.
maxv = -999.
minu = 999.
minv = 999.
idxUnknow = (abs(u) > UNKNOWN_FLOW_THRESH) | (abs(v) > UNKNOWN_FLOW_THRESH)
u[idxUnknow] = 0
v[idxUnknow] = 0
maxu = max(maxu, np.max(u))
minu = min(minu, np.min(u))
maxv = max(maxv, np.max(v))
minv = min(minv, np.min(v))
rad = np.sqrt(u ** 2 + v ** 2)
maxrad = max(-1, np.max(rad))
u = u / (maxrad + np.finfo(float).eps)
v = v / (maxrad + np.finfo(float).eps)
img = compute_color(u, v)
idx = np.repeat(idxUnknow[:, :, np.newaxis], 3, axis=2)
img[idx] = 0
return np.uint8(img)
def compute_color(u, v):
"""
compute optical flow color map
:param u: optical flow horizontal map
:param v: optical flow vertical map
:return: optical flow in color code
"""
[h, w] = u.shape
img = np.zeros([h, w, 3])
nanIdx = np.isnan(u) | np.isnan(v)
u[nanIdx] = 0
v[nanIdx] = 0
colorwheel = make_color_wheel()
ncols = np.size(colorwheel, 0)
rad = np.sqrt(u ** 2 + v ** 2)
a = np.arctan2(-v, -u) / np.pi
fk = (a + 1) / 2 * (ncols - 1) + 1
k0 = np.floor(fk).astype(int)
k1 = k0 + 1
k1[k1 == ncols + 1] = 1
f = fk - k0
for i in range(0, np.size(colorwheel, 1)):
tmp = colorwheel[:, i]
col0 = tmp[k0 - 1] / 255
col1 = tmp[k1 - 1] / 255
col = (1 - f) * col0 + f * col1
idx = rad <= 1
col[idx] = 1 - rad[idx] * (1 - col[idx])
notidx = np.logical_not(idx)
col[notidx] *= 0.75
img[:, :, i] = np.uint8(np.floor(255 * col * (1 - nanIdx)))
return img
def make_color_wheel():
"""
Generate color wheel according Middlebury color code
:return: Color wheel
"""
RY = 15
YG = 6
GC = 4
CB = 11
BM = 13
MR = 6
ncols = RY + YG + GC + CB + BM + MR
colorwheel = np.zeros([ncols, 3])
col = 0
# RY
colorwheel[0:RY, 0] = 255
colorwheel[0:RY, 1] = np.transpose(np.floor(255 * np.arange(0, RY) / RY))
col += RY
# YG
colorwheel[col:col + YG, 0] = 255 - np.transpose(np.floor(255 * np.arange(0, YG) / YG))
colorwheel[col:col + YG, 1] = 255
col += YG
# GC
colorwheel[col:col + GC, 1] = 255
colorwheel[col:col + GC, 2] = np.transpose(np.floor(255 * np.arange(0, GC) / GC))
col += GC
# CB
colorwheel[col:col + CB, 1] = 255 - np.transpose(np.floor(255 * np.arange(0, CB) / CB))
colorwheel[col:col + CB, 2] = 255
col += CB
# BM
colorwheel[col:col + BM, 2] = 255
colorwheel[col:col + BM, 0] = np.transpose(np.floor(255 * np.arange(0, BM) / BM))
col += + BM
# MR
colorwheel[col:col + MR, 2] = 255 - np.transpose(np.floor(255 * np.arange(0, MR) / MR))
colorwheel[col:col + MR, 0] = 255
return colorwheel
|