add gcnet model (#166)

* add gcnet model : https://arxiv.org/abs/1904.11492

configs/gcnet/README.md

+# GCNet: Non-local Networks Meet Squeeze-Excitation Networks and Beyond
+
+## Introduction
+
+- GCNet: Non-local Networks Meet Squeeze-Excitation Networks and Beyond
+: [https://arxiv.org/abs/1904.11492](https://arxiv.org/abs/1904.11492)
+
+```
+@article{DBLP:journals/corr/abs-1904-11492,
+  author    = {Yue Cao and
+               Jiarui Xu and
+               Stephen Lin and
+               Fangyun Wei and
+               Han Hu},
+  title     = {GCNet: Non-local Networks Meet Squeeze-Excitation Networks and Beyond},
+  journal   = {CoRR},
+  volume    = {abs/1904.11492},
+  year      = {2019},
+  url       = {http://arxiv.org/abs/1904.11492},
+  archivePrefix = {arXiv},
+  eprint    = {1904.11492},
+  timestamp = {Tue, 09 Jul 2019 16:48:55 +0200},
+  biburl    = {https://dblp.org/rec/bib/journals/corr/abs-1904-11492},
+  bibsource = {dblp computer science bibliography, https://dblp.org}
+}
+```
+
+
+## Model Zoo
+
+| Backbone                | Type       |     Context| Image/gpu | Lr schd | Inf time (fps) | Box AP | Mask AP |                           Download                           |
+| :---------------------- | :-------------: |  :-------------:  | :-------: | :-----: | :------------: | :----: | :-----: | :----------------------------------------------------------: |
+| ResNet50-vd-FPN         | Mask       | GC(c3-c5, r16, add)  |     2     |   2x    |     15.31     |  41.4  |    36.8    | [model](https://paddlemodels.bj.bcebos.com/object_detection/mask_rcnn_r50_vd_fpn_gcb_add_r16_2x.tar) |
+| ResNet50-vd-FPN         | Mask       | GC(c3-c5, r16, mul)  |     2     |   2x    |     15.35     |  40.7  |    36.1    | [model](https://paddlemodels.bj.bcebos.com/object_detection/mask_rcnn_r50_vd_fpn_gcb_mul_r16_2x.tar) |

configs/gcnet/mask_rcnn_r50_vd_fpn_gcb_add_r16_2x.yml

+architecture: MaskRCNN
+use_gpu: true
+max_iters: 180000
+snapshot_iter: 10000
+log_smooth_window: 20
+save_dir: output
+pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet50_vd_pretrained.tar
+metric: COCO
+weights: output/mask_rcnn_r50_vd_fpn_gcb_add_r16_2x/model_final/
+num_classes: 81
+
+MaskRCNN:
+  backbone: ResNet
+  fpn: FPN
+  rpn_head: FPNRPNHead
+  roi_extractor: FPNRoIAlign
+  bbox_head: BBoxHead
+  bbox_assigner: BBoxAssigner
+
+ResNet:
+  depth: 50
+  feature_maps: [2, 3, 4, 5]
+  freeze_at: 2
+  norm_type: bn
+  variant: d
+  gcb_stages: [3, 4, 5]
+  gcb_params:
+    ratio: 0.0625
+    pooling_type: att
+    fusion_types: [channel_add]
+
+FPN:
+  max_level: 6
+  min_level: 2
+  num_chan: 256
+  spatial_scale: [0.03125, 0.0625, 0.125, 0.25]
+
+FPNRPNHead:
+  anchor_generator:
+    aspect_ratios: [0.5, 1.0, 2.0]
+    variance: [1.0, 1.0, 1.0, 1.0]
+  anchor_start_size: 32
+  max_level: 6
+  min_level: 2
+  num_chan: 256
+  rpn_target_assign:
+    rpn_batch_size_per_im: 256
+    rpn_fg_fraction: 0.5
+    rpn_negative_overlap: 0.3
+    rpn_positive_overlap: 0.7
+    rpn_straddle_thresh: 0.0
+  train_proposal:
+    min_size: 0.0
+    nms_thresh: 0.7
+    pre_nms_top_n: 2000
+    post_nms_top_n: 2000
+  test_proposal:
+    min_size: 0.0
+    nms_thresh: 0.7
+    pre_nms_top_n: 1000
+    post_nms_top_n: 1000
+
+FPNRoIAlign:
+  canconical_level: 4
+  canonical_size: 224
+  max_level: 5
+  min_level: 2
+  box_resolution: 7
+  sampling_ratio: 2
+  mask_resolution: 14
+
+MaskHead:
+  dilation: 1
+  conv_dim: 256
+  num_convs: 4
+  resolution: 28
+
+BBoxAssigner:
+  batch_size_per_im: 512
+  bbox_reg_weights: [0.1, 0.1, 0.2, 0.2]
+  bg_thresh_hi: 0.5
+  bg_thresh_lo: 0.0
+  fg_fraction: 0.25
+  fg_thresh: 0.5
+
+MaskAssigner:
+  resolution: 28
+
+BBoxHead:
+  head: TwoFCHead
+  nms:
+    keep_top_k: 100
+    nms_threshold: 0.5
+    score_threshold: 0.05
+
+TwoFCHead:
+  mlp_dim: 1024
+
+LearningRate:
+  base_lr: 0.02
+  schedulers:
+  - !PiecewiseDecay
+    gamma: 0.1
+    milestones: [120000, 160000]
+  - !LinearWarmup
+    start_factor: 0.1
+    steps: 1000
+
+OptimizerBuilder:
+  optimizer:
+    momentum: 0.9
+    type: Momentum
+  regularizer:
+    factor: 0.0001
+    type: L2
+
+_READER_: '../mask_fpn_reader.yml'
+TrainReader:
+  batch_size: 2

configs/gcnet/mask_rcnn_r50_vd_fpn_gcb_mul_r16_2x.yml

+architecture: MaskRCNN
+use_gpu: true
+max_iters: 180000
+snapshot_iter: 10000
+log_smooth_window: 20
+save_dir: output
+pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet50_vd_pretrained.tar
+metric: COCO
+weights: output/mask_rcnn_r50_vd_fpn_gcb_mul_r16_2x/model_final/
+num_classes: 81
+
+MaskRCNN:
+  backbone: ResNet
+  fpn: FPN
+  rpn_head: FPNRPNHead
+  roi_extractor: FPNRoIAlign
+  bbox_head: BBoxHead
+  bbox_assigner: BBoxAssigner
+
+ResNet:
+  depth: 50
+  feature_maps: [2, 3, 4, 5]
+  freeze_at: 2
+  norm_type: bn
+  variant: d
+  gcb_stages: [3, 4, 5]
+  gcb_params:
+    ratio: 0.0625
+    pooling_type: att
+    fusion_types: [channel_mul]
+
+FPN:
+  max_level: 6
+  min_level: 2
+  num_chan: 256
+  spatial_scale: [0.03125, 0.0625, 0.125, 0.25]
+
+FPNRPNHead:
+  anchor_generator:
+    aspect_ratios: [0.5, 1.0, 2.0]
+    variance: [1.0, 1.0, 1.0, 1.0]
+  anchor_start_size: 32
+  max_level: 6
+  min_level: 2
+  num_chan: 256
+  rpn_target_assign:
+    rpn_batch_size_per_im: 256
+    rpn_fg_fraction: 0.5
+    rpn_negative_overlap: 0.3
+    rpn_positive_overlap: 0.7
+    rpn_straddle_thresh: 0.0
+  train_proposal:
+    min_size: 0.0
+    nms_thresh: 0.7
+    pre_nms_top_n: 2000
+    post_nms_top_n: 2000
+  test_proposal:
+    min_size: 0.0
+    nms_thresh: 0.7
+    pre_nms_top_n: 1000
+    post_nms_top_n: 1000
+
+FPNRoIAlign:
+  canconical_level: 4
+  canonical_size: 224
+  max_level: 5
+  min_level: 2
+  box_resolution: 7
+  sampling_ratio: 2
+  mask_resolution: 14
+
+MaskHead:
+  dilation: 1
+  conv_dim: 256
+  num_convs: 4
+  resolution: 28
+
+BBoxAssigner:
+  batch_size_per_im: 512
+  bbox_reg_weights: [0.1, 0.1, 0.2, 0.2]
+  bg_thresh_hi: 0.5
+  bg_thresh_lo: 0.0
+  fg_fraction: 0.25
+  fg_thresh: 0.5
+
+MaskAssigner:
+  resolution: 28
+
+BBoxHead:
+  head: TwoFCHead
+  nms:
+    keep_top_k: 100
+    nms_threshold: 0.5
+    score_threshold: 0.05
+
+TwoFCHead:
+  mlp_dim: 1024
+
+LearningRate:
+  base_lr: 0.02
+  schedulers:
+  - !PiecewiseDecay
+    gamma: 0.1
+    milestones: [120000, 160000]
+  - !LinearWarmup
+    start_factor: 0.1
+    steps: 1000
+
+OptimizerBuilder:
+  optimizer:
+    momentum: 0.9
+    type: Momentum
+  regularizer:
+    factor: 0.0001
+    type: L2
+
+_READER_: '../mask_fpn_reader.yml'
+TrainReader:
+  batch_size: 2

docs/MODEL_ZOO.md

@@ -102,6 +102,9 @@ The backbone models pretrained on ImageNet are available. All backbone models ar
 ### IOU loss
 * GIOU loss and DIOU loss are included now. See more details in [IOU loss model zoo](../configs/iou_loss/README.md).
 
+### GCNet
+* See more details in [GCNet model zoo](../configs/gcnet/README.md).
+
 
 ### Group Normalization
 | Backbone             | Type           | Image/gpu | Lr schd | Box AP | Mask AP |                           Download                           |

docs/MODEL_ZOO_cn.md

@@ -99,6 +99,9 @@ Paddle提供基于ImageNet的骨架网络预训练模型。所有预训练模型
 ### IOU loss
 * 目前模型库中包括GIOU loss和DIOU loss，详情加[IOU loss模型库](../configs/iou_loss/README.md).
 
+### GCNet
+* 详情见[GCNet模型库](../configs/gcnet/README.md).
+
 
 ### Group Normalization
 | 骨架网络             | 网络类型           | 每张GPU图片个数 | 学习率策略 | Box AP | Mask AP |                           下载                           |

ppdet/modeling/backbones/gc_block.py

+# Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid import ParamAttr
+from paddle.fluid.initializer import ConstantInitializer
+
+
+def spatial_pool(x, pooling_type, name):
+    _, channel, height, width = x.shape
+    if pooling_type == 'att':
+        input_x = x
+        # [N, 1, C, H * W]
+        input_x = fluid.layers.reshape(input_x, shape=(0, 1, channel, -1))
+        context_mask = fluid.layers.conv2d(
+            input=x,
+            num_filters=1,
+            filter_size=1,
+            stride=1,
+            padding=0,
+            param_attr=ParamAttr(name=name + "_weights"),
+            bias_attr=ParamAttr(name=name + "_bias"))
+        # [N, 1, H * W]
+        context_mask = fluid.layers.reshape(context_mask, shape=(0, 0, -1))
+        # [N, 1, H * W]
+        context_mask = fluid.layers.softmax(context_mask, axis=2)
+        # [N, 1, H * W, 1]
+        context_mask = fluid.layers.reshape(context_mask, shape=(0, 0, -1, 1))
+        # [N, 1, C, 1]
+        context = fluid.layers.matmul(input_x, context_mask)
+        # [N, C, 1, 1]
+        context = fluid.layers.reshape(context, shape=(0, channel, 1, 1))
+    else:
+        # [N, C, 1, 1]
+        context = fluid.layers.pool2d(
+            input=x, pool_type='avg', global_pooling=True)
+    return context
+
+
+def channel_conv(input, inner_ch, out_ch, name):
+    conv = fluid.layers.conv2d(
+        input=input,
+        num_filters=inner_ch,
+        filter_size=1,
+        stride=1,
+        padding=0,
+        param_attr=ParamAttr(name=name + "_conv1_weights"),
+        bias_attr=ParamAttr(name=name + "_conv1_bias"),
+        name=name + "_conv1", )
+    conv = fluid.layers.layer_norm(
+        conv,
+        begin_norm_axis=1,
+        param_attr=ParamAttr(name=name + "_ln_weights"),
+        bias_attr=ParamAttr(name=name + "_ln_bias"),
+        act="relu",
+        name=name + "_ln")
+
+    conv = fluid.layers.conv2d(
+        input=conv,
+        num_filters=out_ch,
+        filter_size=1,
+        stride=1,
+        padding=0,
+        param_attr=ParamAttr(
+            name=name + "_conv2_weights",
+            initializer=ConstantInitializer(value=0.0), ),
+        bias_attr=ParamAttr(
+            name=name + "_conv2_bias",
+            initializer=ConstantInitializer(value=0.0), ),
+        name=name + "_conv2")
+    return conv
+
+
+def add_gc_block(x,
+                 ratio=1.0 / 16,
+                 pooling_type='att',
+                 fusion_types=['channel_add'],
+                 name=None):
+    '''
+    GCNet: Non-local Networks Meet Squeeze-Excitation Networks and Beyond, see https://arxiv.org/abs/1904.11492
+    Args:
+        ratio (float): channel reduction ratio
+        pooling_type (str): pooling type, support att and avg
+        fusion_types (list): fusion types, support channel_add and channel_mul
+        name (str): prefix name of gc block
+    '''
+    assert pooling_type in ['avg', 'att']
+    assert isinstance(fusion_types, (list, tuple))
+    valid_fusion_types = ['channel_add', 'channel_mul']
+    assert all([f in valid_fusion_types for f in fusion_types])
+    assert len(fusion_types) > 0, 'at least one fusion should be used'
+
+    inner_ch = int(ratio * x.shape[1])
+    out_ch = x.shape[1]
+    context = spatial_pool(x, pooling_type, name + "_spatial_pool")
+    out = x
+    if 'channel_mul' in fusion_types:
+        inner_out = channel_conv(context, inner_ch, out_ch, name + "_mul")
+        channel_mul_term = fluid.layers.sigmoid(inner_out)
+        out = out * channel_mul_term
+
+    if 'channel_add' in fusion_types:
+        channel_add_term = channel_conv(context, inner_ch, out_ch,
+                                        name + "_add")
+        out = out + channel_add_term
+
+    return out

ppdet/modeling/backbones/resnet.py

@@ -28,6 +28,7 @@ from ppdet.core.workspace import register, serializable
 from numbers import Integral
 
 from .nonlocal_helper import add_space_nonlocal
+from .gc_block import add_gc_block
 from .name_adapter import NameAdapter
 
 __all__ = ['ResNet', 'ResNetC5']
@@ -48,6 +49,10 @@ class ResNet(object):
         feature_maps (list): index of stages whose feature maps are returned
         dcn_v2_stages (list): index of stages who select deformable conv v2
         nonlocal_stages (list): index of stages who select nonlocal networks
+        gcb_stages (list): index of stages who select gc blocks
+        gcb_params (dict): gc blocks config, includes ratio(default as 1.0/16),
+                           pooling_type(default as "att") and
+                           fusion_types(default as ['channel_add'])
     """
     __shared__ = ['norm_type', 'freeze_norm', 'weight_prefix_name']
 
@@ -61,7 +66,9 @@ class ResNet(object):
                  feature_maps=[2, 3, 4, 5],
                  dcn_v2_stages=[],
                  weight_prefix_name='',
-                 nonlocal_stages=[]):
+                 nonlocal_stages=[],
+                 gcb_stages=[],
+                 gcb_params=dict()):
         super(ResNet, self).__init__()
 
         if isinstance(feature_maps, Integral):
@@ -97,15 +104,18 @@ class ResNet(object):
         self._c1_out_chan_num = 64
         self.na = NameAdapter(self)
         self.prefix_name = weight_prefix_name
-        
+
         self.nonlocal_stages = nonlocal_stages
         self.nonlocal_mod_cfg = {
-            50  : 2,
-            101 : 5,
-            152 : 8,
-            200 : 12,
+            50: 2,
+            101: 5,
+            152: 8,
+            200: 12,
         }
 
+        self.gcb_stages = gcb_stages
+        self.gcb_params = gcb_params
+
     def _conv_offset(self,
                      input,
                      filter_size,
@@ -257,7 +267,9 @@ class ResNet(object):
                    stride,
                    is_first,
                    name,
-                   dcn_v2=False):
+                   dcn_v2=False,
+                   gcb=False,
+                   gcb_name=None):
         if self.variant == 'a':
             stride1, stride2 = stride, 1
         else:
@@ -309,6 +321,8 @@ class ResNet(object):
         if callable(getattr(self, '_squeeze_excitation', None)):
             residual = self._squeeze_excitation(
                 input=residual, num_channels=num_filters, name='fc' + name)
+        if gcb:
+            residual = add_gc_block(residual, name=gcb_name, **self.gcb_params)
         return fluid.layers.elementwise_add(
             x=short, y=residual, act='relu', name=name + ".add.output.5")
 
@@ -318,8 +332,11 @@ class ResNet(object):
                    stride,
                    is_first,
                    name,
-                   dcn_v2=False):
+                   dcn_v2=False,
+                   gcb=False,
+                   gcb_name=None):
         assert dcn_v2 is False, "Not implemented yet."
+        assert gcb is False, "Not implemented yet."
         conv0 = self._conv_norm(
             input=input,
             num_filters=num_filters,
@@ -354,11 +371,12 @@ class ResNet(object):
         ch_out = self.stage_filters[stage_num - 2]
         is_first = False if stage_num != 2 else True
         dcn_v2 = True if stage_num in self.dcn_v2_stages else False
-        
+
         nonlocal_mod = 1000
         if stage_num in self.nonlocal_stages:
-            nonlocal_mod = self.nonlocal_mod_cfg[self.depth] if stage_num==4 else 2
-        
+            nonlocal_mod = self.nonlocal_mod_cfg[
+                self.depth] if stage_num == 4 else 2
+
         # Make the layer name and parameter name consistent
         # with ImageNet pre-trained model
         conv = input
@@ -366,21 +384,26 @@ class ResNet(object):
             conv_name = self.na.fix_layer_warp_name(stage_num, count, i)
             if self.depth < 50:
                 is_first = True if i == 0 and stage_num == 2 else False
+
+            gcb = stage_num in self.gcb_stages
+            gcb_name = "gcb_res{}_b{}".format(stage_num, i)
             conv = block_func(
                 input=conv,
                 num_filters=ch_out,
                 stride=2 if i == 0 and stage_num != 2 else 1,
                 is_first=is_first,
                 name=conv_name,
-                dcn_v2=dcn_v2)
-            
+                dcn_v2=dcn_v2,
+                gcb=gcb,
+                gcb_name=gcb_name)
+
             # add non local model
             dim_in = conv.shape[1]
-            nonlocal_name = "nonlocal_conv{}".format( stage_num )
+            nonlocal_name = "nonlocal_conv{}".format(stage_num)
             if i % nonlocal_mod == nonlocal_mod - 1:
-                conv = add_space_nonlocal(
-                    conv, dim_in, dim_in,
-                    nonlocal_name + '_{}'.format(i), int(dim_in / 2) )
+                conv = add_space_nonlocal(conv, dim_in, dim_in,
+                                          nonlocal_name + '_{}'.format(i),
+                                          int(dim_in / 2))
         return conv
 
     def c1_stage(self, input):