File size: 9,108 Bytes
983684c
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
import numpy as np
import random
import math
from PIL import Image

import cv2
cv2.setNumThreads(0)
cv2.ocl.setUseOpenCL(False)

import torch
from torchvision.transforms import ColorJitter
import torch.nn.functional as F


class FlowAugmentor:
    def __init__(self, crop_size, min_scale=-0.2, max_scale=0.5, do_flip=True):
        
        # spatial augmentation params
        self.crop_size = crop_size
        self.min_scale = min_scale
        self.max_scale = max_scale
        self.spatial_aug_prob = 0.8
        self.stretch_prob = 0.8
        self.max_stretch = 0.2

        # flip augmentation params
        self.do_flip = do_flip
        self.h_flip_prob = 0.5
        self.v_flip_prob = 0.1

        # photometric augmentation params
        self.photo_aug = ColorJitter(brightness=0.4, contrast=0.4, saturation=0.4, hue=0.5/3.14)
        self.asymmetric_color_aug_prob = 0.2
        self.eraser_aug_prob = 0.5

    def color_transform(self, img1, img2):
        """ Photometric augmentation """

        # asymmetric
        if np.random.rand() < self.asymmetric_color_aug_prob:
            img1 = np.array(self.photo_aug(Image.fromarray(img1)), dtype=np.uint8)
            img2 = np.array(self.photo_aug(Image.fromarray(img2)), dtype=np.uint8)

        # symmetric
        else:
            image_stack = np.concatenate([img1, img2], axis=0)
            image_stack = np.array(self.photo_aug(Image.fromarray(image_stack)), dtype=np.uint8)
            img1, img2 = np.split(image_stack, 2, axis=0)

        return img1, img2

    def eraser_transform(self, img1, img2, bounds=[50, 100]):
        """ Occlusion augmentation """

        ht, wd = img1.shape[:2]
        if np.random.rand() < self.eraser_aug_prob:
            mean_color = np.mean(img2.reshape(-1, 3), axis=0)
            for _ in range(np.random.randint(1, 3)):
                x0 = np.random.randint(0, wd)
                y0 = np.random.randint(0, ht)
                dx = np.random.randint(bounds[0], bounds[1])
                dy = np.random.randint(bounds[0], bounds[1])
                img2[y0:y0+dy, x0:x0+dx, :] = mean_color

        return img1, img2

    def spatial_transform(self, img1, img2, flow):
        # randomly sample scale
        ht, wd = img1.shape[:2]
        min_scale = np.maximum(
            (self.crop_size[0] + 8) / float(ht), 
            (self.crop_size[1] + 8) / float(wd))

        scale = 2 ** np.random.uniform(self.min_scale, self.max_scale)
        scale_x = scale
        scale_y = scale
        if np.random.rand() < self.stretch_prob:
            scale_x *= 2 ** np.random.uniform(-self.max_stretch, self.max_stretch)
            scale_y *= 2 ** np.random.uniform(-self.max_stretch, self.max_stretch)
        
        scale_x = np.clip(scale_x, min_scale, None)
        scale_y = np.clip(scale_y, min_scale, None)

        if np.random.rand() < self.spatial_aug_prob:
            # rescale the images
            img1 = cv2.resize(img1, None, fx=scale_x, fy=scale_y, interpolation=cv2.INTER_LINEAR)
            img2 = cv2.resize(img2, None, fx=scale_x, fy=scale_y, interpolation=cv2.INTER_LINEAR)
            flow = cv2.resize(flow, None, fx=scale_x, fy=scale_y, interpolation=cv2.INTER_LINEAR)
            flow = flow * [scale_x, scale_y]

        if self.do_flip:
            if np.random.rand() < self.h_flip_prob: # h-flip
                img1 = img1[:, ::-1]
                img2 = img2[:, ::-1]
                flow = flow[:, ::-1] * [-1.0, 1.0]

            if np.random.rand() < self.v_flip_prob: # v-flip
                img1 = img1[::-1, :]
                img2 = img2[::-1, :]
                flow = flow[::-1, :] * [1.0, -1.0]

        y0 = np.random.randint(0, img1.shape[0] - self.crop_size[0])
        x0 = np.random.randint(0, img1.shape[1] - self.crop_size[1])
        
        img1 = img1[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        img2 = img2[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        flow = flow[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]

        return img1, img2, flow

    def __call__(self, img1, img2, flow):
        img1, img2 = self.color_transform(img1, img2)
        img1, img2 = self.eraser_transform(img1, img2)
        img1, img2, flow = self.spatial_transform(img1, img2, flow)

        img1 = np.ascontiguousarray(img1)
        img2 = np.ascontiguousarray(img2)
        flow = np.ascontiguousarray(flow)

        return img1, img2, flow

class SparseFlowAugmentor:
    def __init__(self, crop_size, min_scale=-0.2, max_scale=0.5, do_flip=False):
        # spatial augmentation params
        self.crop_size = crop_size
        self.min_scale = min_scale
        self.max_scale = max_scale
        self.spatial_aug_prob = 0.8
        self.stretch_prob = 0.8
        self.max_stretch = 0.2

        # flip augmentation params
        self.do_flip = do_flip
        self.h_flip_prob = 0.5
        self.v_flip_prob = 0.1

        # photometric augmentation params
        self.photo_aug = ColorJitter(brightness=0.3, contrast=0.3, saturation=0.3, hue=0.3/3.14)
        self.asymmetric_color_aug_prob = 0.2
        self.eraser_aug_prob = 0.5
        
    def color_transform(self, img1, img2):
        image_stack = np.concatenate([img1, img2], axis=0)
        image_stack = np.array(self.photo_aug(Image.fromarray(image_stack)), dtype=np.uint8)
        img1, img2 = np.split(image_stack, 2, axis=0)
        return img1, img2

    def eraser_transform(self, img1, img2):
        ht, wd = img1.shape[:2]
        if np.random.rand() < self.eraser_aug_prob:
            mean_color = np.mean(img2.reshape(-1, 3), axis=0)
            for _ in range(np.random.randint(1, 3)):
                x0 = np.random.randint(0, wd)
                y0 = np.random.randint(0, ht)
                dx = np.random.randint(50, 100)
                dy = np.random.randint(50, 100)
                img2[y0:y0+dy, x0:x0+dx, :] = mean_color

        return img1, img2

    def resize_sparse_flow_map(self, flow, valid, fx=1.0, fy=1.0):
        ht, wd = flow.shape[:2]
        coords = np.meshgrid(np.arange(wd), np.arange(ht))
        coords = np.stack(coords, axis=-1)

        coords = coords.reshape(-1, 2).astype(np.float32)
        flow = flow.reshape(-1, 2).astype(np.float32)
        valid = valid.reshape(-1).astype(np.float32)

        coords0 = coords[valid>=1]
        flow0 = flow[valid>=1]

        ht1 = int(round(ht * fy))
        wd1 = int(round(wd * fx))

        coords1 = coords0 * [fx, fy]
        flow1 = flow0 * [fx, fy]

        xx = np.round(coords1[:,0]).astype(np.int32)
        yy = np.round(coords1[:,1]).astype(np.int32)

        v = (xx > 0) & (xx < wd1) & (yy > 0) & (yy < ht1)
        xx = xx[v]
        yy = yy[v]
        flow1 = flow1[v]

        flow_img = np.zeros([ht1, wd1, 2], dtype=np.float32)
        valid_img = np.zeros([ht1, wd1], dtype=np.int32)

        flow_img[yy, xx] = flow1
        valid_img[yy, xx] = 1

        return flow_img, valid_img

    def spatial_transform(self, img1, img2, flow, valid):
        # randomly sample scale

        ht, wd = img1.shape[:2]
        min_scale = np.maximum(
            (self.crop_size[0] + 1) / float(ht), 
            (self.crop_size[1] + 1) / float(wd))

        scale = 2 ** np.random.uniform(self.min_scale, self.max_scale)
        scale_x = np.clip(scale, min_scale, None)
        scale_y = np.clip(scale, min_scale, None)

        if np.random.rand() < self.spatial_aug_prob:
            # rescale the images
            img1 = cv2.resize(img1, None, fx=scale_x, fy=scale_y, interpolation=cv2.INTER_LINEAR)
            img2 = cv2.resize(img2, None, fx=scale_x, fy=scale_y, interpolation=cv2.INTER_LINEAR)
            flow, valid = self.resize_sparse_flow_map(flow, valid, fx=scale_x, fy=scale_y)

        if self.do_flip:
            if np.random.rand() < 0.5: # h-flip
                img1 = img1[:, ::-1]
                img2 = img2[:, ::-1]
                flow = flow[:, ::-1] * [-1.0, 1.0]
                valid = valid[:, ::-1]

        margin_y = 20
        margin_x = 50

        y0 = np.random.randint(0, img1.shape[0] - self.crop_size[0] + margin_y)
        x0 = np.random.randint(-margin_x, img1.shape[1] - self.crop_size[1] + margin_x)

        y0 = np.clip(y0, 0, img1.shape[0] - self.crop_size[0])
        x0 = np.clip(x0, 0, img1.shape[1] - self.crop_size[1])

        img1 = img1[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        img2 = img2[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        flow = flow[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        valid = valid[y0:y0+self.crop_size[0], x0:x0+self.crop_size[1]]
        return img1, img2, flow, valid


    def __call__(self, img1, img2, flow, valid):
        img1, img2 = self.color_transform(img1, img2)
        img1, img2 = self.eraser_transform(img1, img2)
        img1, img2, flow, valid = self.spatial_transform(img1, img2, flow, valid)

        img1 = np.ascontiguousarray(img1)
        img2 = np.ascontiguousarray(img2)
        flow = np.ascontiguousarray(flow)
        valid = np.ascontiguousarray(valid)

        return img1, img2, flow, valid