File size: 14,405 Bytes
b334e29
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
import torch
import torch.nn as nn
from mmcv.cnn import ConvModule, normal_init
from mmcv.ops import DeformConv2d

from mmdet.core import multi_apply, multiclass_nms
from ..builder import HEADS
from .anchor_free_head import AnchorFreeHead

INF = 1e8


class FeatureAlign(nn.Module):

    def __init__(self,
                 in_channels,
                 out_channels,
                 kernel_size=3,
                 deform_groups=4):
        super(FeatureAlign, self).__init__()
        offset_channels = kernel_size * kernel_size * 2
        self.conv_offset = nn.Conv2d(
            4, deform_groups * offset_channels, 1, bias=False)
        self.conv_adaption = DeformConv2d(
            in_channels,
            out_channels,
            kernel_size=kernel_size,
            padding=(kernel_size - 1) // 2,
            deform_groups=deform_groups)
        self.relu = nn.ReLU(inplace=True)

    def init_weights(self):
        normal_init(self.conv_offset, std=0.1)
        normal_init(self.conv_adaption, std=0.01)

    def forward(self, x, shape):
        offset = self.conv_offset(shape)
        x = self.relu(self.conv_adaption(x, offset))
        return x


@HEADS.register_module()
class FoveaHead(AnchorFreeHead):
    """FoveaBox: Beyond Anchor-based Object Detector
    https://arxiv.org/abs/1904.03797
    """

    def __init__(self,
                 num_classes,
                 in_channels,
                 base_edge_list=(16, 32, 64, 128, 256),
                 scale_ranges=((8, 32), (16, 64), (32, 128), (64, 256), (128,
                                                                         512)),
                 sigma=0.4,
                 with_deform=False,
                 deform_groups=4,
                 **kwargs):
        self.base_edge_list = base_edge_list
        self.scale_ranges = scale_ranges
        self.sigma = sigma
        self.with_deform = with_deform
        self.deform_groups = deform_groups
        super().__init__(num_classes, in_channels, **kwargs)

    def _init_layers(self):
        # box branch
        super()._init_reg_convs()
        self.conv_reg = nn.Conv2d(self.feat_channels, 4, 3, padding=1)

        # cls branch
        if not self.with_deform:
            super()._init_cls_convs()
            self.conv_cls = nn.Conv2d(
                self.feat_channels, self.cls_out_channels, 3, padding=1)
        else:
            self.cls_convs = nn.ModuleList()
            self.cls_convs.append(
                ConvModule(
                    self.feat_channels, (self.feat_channels * 4),
                    3,
                    stride=1,
                    padding=1,
                    conv_cfg=self.conv_cfg,
                    norm_cfg=self.norm_cfg,
                    bias=self.norm_cfg is None))
            self.cls_convs.append(
                ConvModule((self.feat_channels * 4), (self.feat_channels * 4),
                           1,
                           stride=1,
                           padding=0,
                           conv_cfg=self.conv_cfg,
                           norm_cfg=self.norm_cfg,
                           bias=self.norm_cfg is None))
            self.feature_adaption = FeatureAlign(
                self.feat_channels,
                self.feat_channels,
                kernel_size=3,
                deform_groups=self.deform_groups)
            self.conv_cls = nn.Conv2d(
                int(self.feat_channels * 4),
                self.cls_out_channels,
                3,
                padding=1)

    def init_weights(self):
        super().init_weights()
        if self.with_deform:
            self.feature_adaption.init_weights()

    def forward_single(self, x):
        cls_feat = x
        reg_feat = x
        for reg_layer in self.reg_convs:
            reg_feat = reg_layer(reg_feat)
        bbox_pred = self.conv_reg(reg_feat)
        if self.with_deform:
            cls_feat = self.feature_adaption(cls_feat, bbox_pred.exp())
        for cls_layer in self.cls_convs:
            cls_feat = cls_layer(cls_feat)
        cls_score = self.conv_cls(cls_feat)
        return cls_score, bbox_pred

    def _get_points_single(self, *args, **kwargs):
        y, x = super()._get_points_single(*args, **kwargs)
        return y + 0.5, x + 0.5

    def loss(self,
             cls_scores,
             bbox_preds,
             gt_bbox_list,
             gt_label_list,
             img_metas,
             gt_bboxes_ignore=None):
        assert len(cls_scores) == len(bbox_preds)

        featmap_sizes = [featmap.size()[-2:] for featmap in cls_scores]
        points = self.get_points(featmap_sizes, bbox_preds[0].dtype,
                                 bbox_preds[0].device)
        num_imgs = cls_scores[0].size(0)
        flatten_cls_scores = [
            cls_score.permute(0, 2, 3, 1).reshape(-1, self.cls_out_channels)
            for cls_score in cls_scores
        ]
        flatten_bbox_preds = [
            bbox_pred.permute(0, 2, 3, 1).reshape(-1, 4)
            for bbox_pred in bbox_preds
        ]
        flatten_cls_scores = torch.cat(flatten_cls_scores)
        flatten_bbox_preds = torch.cat(flatten_bbox_preds)
        flatten_labels, flatten_bbox_targets = self.get_targets(
            gt_bbox_list, gt_label_list, featmap_sizes, points)

        # FG cat_id: [0, num_classes -1], BG cat_id: num_classes
        pos_inds = ((flatten_labels >= 0)
                    & (flatten_labels < self.num_classes)).nonzero().view(-1)
        num_pos = len(pos_inds)

        loss_cls = self.loss_cls(
            flatten_cls_scores, flatten_labels, avg_factor=num_pos + num_imgs)
        if num_pos > 0:
            pos_bbox_preds = flatten_bbox_preds[pos_inds]
            pos_bbox_targets = flatten_bbox_targets[pos_inds]
            pos_weights = pos_bbox_targets.new_zeros(
                pos_bbox_targets.size()) + 1.0
            loss_bbox = self.loss_bbox(
                pos_bbox_preds,
                pos_bbox_targets,
                pos_weights,
                avg_factor=num_pos)
        else:
            loss_bbox = torch.tensor(
                0,
                dtype=flatten_bbox_preds.dtype,
                device=flatten_bbox_preds.device)
        return dict(loss_cls=loss_cls, loss_bbox=loss_bbox)

    def get_targets(self, gt_bbox_list, gt_label_list, featmap_sizes, points):
        label_list, bbox_target_list = multi_apply(
            self._get_target_single,
            gt_bbox_list,
            gt_label_list,
            featmap_size_list=featmap_sizes,
            point_list=points)
        flatten_labels = [
            torch.cat([
                labels_level_img.flatten() for labels_level_img in labels_level
            ]) for labels_level in zip(*label_list)
        ]
        flatten_bbox_targets = [
            torch.cat([
                bbox_targets_level_img.reshape(-1, 4)
                for bbox_targets_level_img in bbox_targets_level
            ]) for bbox_targets_level in zip(*bbox_target_list)
        ]
        flatten_labels = torch.cat(flatten_labels)
        flatten_bbox_targets = torch.cat(flatten_bbox_targets)
        return flatten_labels, flatten_bbox_targets

    def _get_target_single(self,
                           gt_bboxes_raw,
                           gt_labels_raw,
                           featmap_size_list=None,
                           point_list=None):

        gt_areas = torch.sqrt((gt_bboxes_raw[:, 2] - gt_bboxes_raw[:, 0]) *
                              (gt_bboxes_raw[:, 3] - gt_bboxes_raw[:, 1]))
        label_list = []
        bbox_target_list = []
        # for each pyramid, find the cls and box target
        for base_len, (lower_bound, upper_bound), stride, featmap_size, \
            (y, x) in zip(self.base_edge_list, self.scale_ranges,
                          self.strides, featmap_size_list, point_list):
            # FG cat_id: [0, num_classes -1], BG cat_id: num_classes
            labels = gt_labels_raw.new_zeros(featmap_size) + self.num_classes
            bbox_targets = gt_bboxes_raw.new(featmap_size[0], featmap_size[1],
                                             4) + 1
            # scale assignment
            hit_indices = ((gt_areas >= lower_bound) &
                           (gt_areas <= upper_bound)).nonzero().flatten()
            if len(hit_indices) == 0:
                label_list.append(labels)
                bbox_target_list.append(torch.log(bbox_targets))
                continue
            _, hit_index_order = torch.sort(-gt_areas[hit_indices])
            hit_indices = hit_indices[hit_index_order]
            gt_bboxes = gt_bboxes_raw[hit_indices, :] / stride
            gt_labels = gt_labels_raw[hit_indices]
            half_w = 0.5 * (gt_bboxes[:, 2] - gt_bboxes[:, 0])
            half_h = 0.5 * (gt_bboxes[:, 3] - gt_bboxes[:, 1])
            # valid fovea area: left, right, top, down
            pos_left = torch.ceil(
                gt_bboxes[:, 0] + (1 - self.sigma) * half_w - 0.5).long().\
                clamp(0, featmap_size[1] - 1)
            pos_right = torch.floor(
                gt_bboxes[:, 0] + (1 + self.sigma) * half_w - 0.5).long().\
                clamp(0, featmap_size[1] - 1)
            pos_top = torch.ceil(
                gt_bboxes[:, 1] + (1 - self.sigma) * half_h - 0.5).long().\
                clamp(0, featmap_size[0] - 1)
            pos_down = torch.floor(
                gt_bboxes[:, 1] + (1 + self.sigma) * half_h - 0.5).long().\
                clamp(0, featmap_size[0] - 1)
            for px1, py1, px2, py2, label, (gt_x1, gt_y1, gt_x2, gt_y2) in \
                    zip(pos_left, pos_top, pos_right, pos_down, gt_labels,
                        gt_bboxes_raw[hit_indices, :]):
                labels[py1:py2 + 1, px1:px2 + 1] = label
                bbox_targets[py1:py2 + 1, px1:px2 + 1, 0] = \
                    (stride * x[py1:py2 + 1, px1:px2 + 1] - gt_x1) / base_len
                bbox_targets[py1:py2 + 1, px1:px2 + 1, 1] = \
                    (stride * y[py1:py2 + 1, px1:px2 + 1] - gt_y1) / base_len
                bbox_targets[py1:py2 + 1, px1:px2 + 1, 2] = \
                    (gt_x2 - stride * x[py1:py2 + 1, px1:px2 + 1]) / base_len
                bbox_targets[py1:py2 + 1, px1:px2 + 1, 3] = \
                    (gt_y2 - stride * y[py1:py2 + 1, px1:px2 + 1]) / base_len
            bbox_targets = bbox_targets.clamp(min=1. / 16, max=16.)
            label_list.append(labels)
            bbox_target_list.append(torch.log(bbox_targets))
        return label_list, bbox_target_list

    def get_bboxes(self,
                   cls_scores,
                   bbox_preds,
                   img_metas,
                   cfg=None,
                   rescale=None):
        assert len(cls_scores) == len(bbox_preds)
        num_levels = len(cls_scores)
        featmap_sizes = [featmap.size()[-2:] for featmap in cls_scores]
        points = self.get_points(
            featmap_sizes,
            bbox_preds[0].dtype,
            bbox_preds[0].device,
            flatten=True)
        result_list = []
        for img_id in range(len(img_metas)):
            cls_score_list = [
                cls_scores[i][img_id].detach() for i in range(num_levels)
            ]
            bbox_pred_list = [
                bbox_preds[i][img_id].detach() for i in range(num_levels)
            ]
            img_shape = img_metas[img_id]['img_shape']
            scale_factor = img_metas[img_id]['scale_factor']
            det_bboxes = self._get_bboxes_single(cls_score_list,
                                                 bbox_pred_list, featmap_sizes,
                                                 points, img_shape,
                                                 scale_factor, cfg, rescale)
            result_list.append(det_bboxes)
        return result_list

    def _get_bboxes_single(self,
                           cls_scores,
                           bbox_preds,
                           featmap_sizes,
                           point_list,
                           img_shape,
                           scale_factor,
                           cfg,
                           rescale=False):
        cfg = self.test_cfg if cfg is None else cfg
        assert len(cls_scores) == len(bbox_preds) == len(point_list)
        det_bboxes = []
        det_scores = []
        for cls_score, bbox_pred, featmap_size, stride, base_len, (y, x) \
                in zip(cls_scores, bbox_preds, featmap_sizes, self.strides,
                       self.base_edge_list, point_list):
            assert cls_score.size()[-2:] == bbox_pred.size()[-2:]
            scores = cls_score.permute(1, 2, 0).reshape(
                -1, self.cls_out_channels).sigmoid()
            bbox_pred = bbox_pred.permute(1, 2, 0).reshape(-1, 4).exp()
            nms_pre = cfg.get('nms_pre', -1)
            if (nms_pre > 0) and (scores.shape[0] > nms_pre):
                max_scores, _ = scores.max(dim=1)
                _, topk_inds = max_scores.topk(nms_pre)
                bbox_pred = bbox_pred[topk_inds, :]
                scores = scores[topk_inds, :]
                y = y[topk_inds]
                x = x[topk_inds]
            x1 = (stride * x - base_len * bbox_pred[:, 0]).\
                clamp(min=0, max=img_shape[1] - 1)
            y1 = (stride * y - base_len * bbox_pred[:, 1]).\
                clamp(min=0, max=img_shape[0] - 1)
            x2 = (stride * x + base_len * bbox_pred[:, 2]).\
                clamp(min=0, max=img_shape[1] - 1)
            y2 = (stride * y + base_len * bbox_pred[:, 3]).\
                clamp(min=0, max=img_shape[0] - 1)
            bboxes = torch.stack([x1, y1, x2, y2], -1)
            det_bboxes.append(bboxes)
            det_scores.append(scores)
        det_bboxes = torch.cat(det_bboxes)
        if rescale:
            det_bboxes /= det_bboxes.new_tensor(scale_factor)
        det_scores = torch.cat(det_scores)
        padding = det_scores.new_zeros(det_scores.shape[0], 1)
        # remind that we set FG labels to [0, num_class-1] since mmdet v2.0
        # BG cat_id: num_class
        det_scores = torch.cat([det_scores, padding], dim=1)
        det_bboxes, det_labels = multiclass_nms(det_bboxes, det_scores,
                                                cfg.score_thr, cfg.nms,
                                                cfg.max_per_img)
        return det_bboxes, det_labels