-
Notifications
You must be signed in to change notification settings - Fork 0
/
flow_viz.py
136 lines (123 loc) · 4.57 KB
/
flow_viz.py
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
# Copyright (c) Meta Platforms, Inc. and affiliates.
# Flow visualization code used from https://github.com/tomrunia/OpticalFlow_Visualization
# MIT License
#
# Copyright (c) 2018 Tom Runia
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to conditions.
#
# Author: Tom Runia
# Date Created: 2018-08-03
import numpy as np
def make_colorwheel():
"""
Generates a color wheel for optical flow visualization as presented in:
Baker et al. "A Database and Evaluation Methodology for Optical Flow" (ICCV, 2007)
URL: http://vision.middlebury.edu/flow/flowEval-iccv07.pdf
Code follows the original C++ source code of Daniel Scharstein.
Code follows the the Matlab source code of Deqing Sun.
Returns:
np.ndarray: 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.floor(255 * np.arange(0, RY) / RY)
col = col + RY
# YG
colorwheel[col : col + YG, 0] = 255 - np.floor(255 * np.arange(0, YG) / YG)
colorwheel[col : col + YG, 1] = 255
col = col + YG
# GC
colorwheel[col : col + GC, 1] = 255
colorwheel[col : col + GC, 2] = np.floor(255 * np.arange(0, GC) / GC)
col = col + GC
# CB
colorwheel[col : col + CB, 1] = 255 - np.floor(255 * np.arange(CB) / CB)
colorwheel[col : col + CB, 2] = 255
col = col + CB
# BM
colorwheel[col : col + BM, 2] = 255
colorwheel[col : col + BM, 0] = np.floor(255 * np.arange(0, BM) / BM)
col = col + BM
# MR
colorwheel[col : col + MR, 2] = 255 - np.floor(255 * np.arange(MR) / MR)
colorwheel[col : col + MR, 0] = 255
return colorwheel
def flow_uv_to_colors(u, v, convert_to_bgr=False):
"""
Applies the flow color wheel to (possibly clipped) flow components u and v.
According to the C++ source code of Daniel Scharstein
According to the Matlab source code of Deqing Sun
Args:
u (np.ndarray): Input horizontal flow of shape [H,W]
v (np.ndarray): Input vertical flow of shape [H,W]
convert_to_bgr (bool, optional): Convert output image to BGR. Defaults to False.
Returns:
np.ndarray: Flow visualization image of shape [H,W,3]
"""
flow_image = np.zeros((u.shape[0], u.shape[1], 3), np.uint8)
colorwheel = make_colorwheel() # shape [55x3]
ncols = colorwheel.shape[0]
rad = np.sqrt(np.square(u) + np.square(v))
a = np.arctan2(-v, -u) / np.pi
fk = (a + 1) / 2 * (ncols - 1)
k0 = np.floor(fk).astype(np.int32)
k1 = k0 + 1
k1[k1 == ncols] = 0
f = fk - k0
for i in range(colorwheel.shape[1]):
tmp = colorwheel[:, i]
col0 = tmp[k0] / 255.0
col1 = tmp[k1] / 255.0
col = (1 - f) * col0 + f * col1
idx = rad <= 1
col[idx] = 1 - rad[idx] * (1 - col[idx])
col[~idx] = col[~idx] * 0.75 # out of range
# Note the 2-i => BGR instead of RGB
ch_idx = 2 - i if convert_to_bgr else i
flow_image[:, :, ch_idx] = np.floor(255 * col)
return flow_image
def flow_to_image(flow_uv, clip_flow=None, convert_to_bgr=False):
"""
Expects a two dimensional flow image of shape.
Args:
flow_uv (np.ndarray): Flow UV image of shape [H,W,2]
clip_flow (float, optional): Clip maximum of flow values. Defaults to None.
convert_to_bgr (bool, optional): Convert output image to BGR. Defaults to False.
Returns:
np.ndarray: Flow visualization image of shape [H,W,3]
"""
assert flow_uv.ndim == 3, "input flow must have three dimensions"
assert flow_uv.shape[2] == 2, "input flow must have shape [H,W,2]"
if clip_flow is not None:
flow_uv = np.clip(flow_uv, 0, clip_flow)
flow_uv[flow_uv == np.inf] = 0
flow_uv[flow_uv == -np.inf] = 0
u = flow_uv[:, :, 0]
v = flow_uv[:, :, 1]
rad = np.sqrt(np.square(u) + np.square(v))
rad_max = np.max(rad)
epsilon = 1e-5
u = u / (rad_max + epsilon)
v = v / (rad_max + epsilon)
u[u == np.inf] = 0
u[u == -np.inf] = 0
v[v == np.inf] = 0
v[v == -np.inf] = 0
u[np.isnan(u)] = 0
v[np.isnan(v)] = 0
return flow_uv_to_colors(u, v, convert_to_bgr)