# coding=utf-8 from __future__ import absolute_import from __future__ import division from __future__ import print_function import math from collections import OrderedDict from numbers import Integral from paddle import fluid from paddle.fluid.param_attr import ParamAttr from paddle.fluid.framework import Variable from paddle.fluid.regularizer import L2Decay from paddle.fluid.initializer import Constant from .nonlocal_helper import add_space_nonlocal from .name_adapter import NameAdapter __all__ = ['ResNet', 'ResNetC5'] class ResNet(object): """ Residual Network, see https://arxiv.org/abs/1512.03385 Args: depth (int): ResNet depth, should be 34, 50. freeze_at (int): freeze the backbone at which stage norm_type (str): normalization type, 'bn'/'sync_bn'/'affine_channel' freeze_norm (bool): freeze normalization layers norm_decay (float): weight decay for normalization layer weights variant (str): ResNet variant, supports 'a', 'b', 'c', 'd' currently 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 """ __shared__ = ['norm_type', 'freeze_norm', 'weight_prefix_name'] def __init__(self, depth=50, freeze_at=0, norm_type='sync_bn', freeze_norm=False, norm_decay=0., variant='b', feature_maps=[3, 4, 5], dcn_v2_stages=[], weight_prefix_name='', nonlocal_stages=[], get_prediction=False, class_dim=1000): super(ResNet, self).__init__() if isinstance(feature_maps, Integral): feature_maps = [feature_maps] assert depth in [34, 50], \ "depth {} not in [34, 50]" assert variant in ['a', 'b', 'c', 'd'], "invalid ResNet variant" assert 0 <= freeze_at <= 4, "freeze_at should be 0, 1, 2, 3 or 4" assert len(feature_maps) > 0, "need one or more feature maps" assert norm_type in ['bn', 'sync_bn', 'affine_channel'] assert not (len(nonlocal_stages)>0 and depth<50), \ "non-local is not supported for resnet18 or resnet34" self.depth = depth self.freeze_at = freeze_at self.norm_type = norm_type self.norm_decay = norm_decay self.freeze_norm = freeze_norm self.variant = variant self._model_type = 'ResNet' self.feature_maps = feature_maps self.dcn_v2_stages = dcn_v2_stages self.depth_cfg = { 34: ([3, 4, 6, 3], self.basicblock), 50: ([3, 4, 6, 3], self.bottleneck), } self.stage_filters = [64, 128, 256, 512] 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, } self.get_prediction = get_prediction self.class_dim = class_dim def _conv_offset(self, input, filter_size, stride, padding, act=None, name=None): out_channel = filter_size * filter_size * 3 out = fluid.layers.conv2d( input, num_filters=out_channel, filter_size=filter_size, stride=stride, padding=padding, param_attr=ParamAttr(initializer=Constant(0.0), name=name + ".w_0"), bias_attr=ParamAttr(initializer=Constant(0.0), name=name + ".b_0"), act=act, name=name) return out def _conv_norm(self, input, num_filters, filter_size, stride=1, groups=1, act=None, name=None, dcn_v2=False): _name = self.prefix_name + name if self.prefix_name != '' else name if not dcn_v2: conv = fluid.layers.conv2d( input=input, num_filters=num_filters, filter_size=filter_size, stride=stride, padding=(filter_size - 1) // 2, groups=groups, act=None, param_attr=ParamAttr(name=_name + "_weights"), bias_attr=False, name=_name + '.conv2d.output.1') else: # select deformable conv" offset_mask = self._conv_offset( input=input, filter_size=filter_size, stride=stride, padding=(filter_size - 1) // 2, act=None, name=_name + "_conv_offset") offset_channel = filter_size**2 * 2 mask_channel = filter_size**2 offset, mask = fluid.layers.split(input=offset_mask, num_or_sections=[offset_channel, mask_channel], dim=1) mask = fluid.layers.sigmoid(mask) conv = fluid.layers.deformable_conv( input=input, offset=offset, mask=mask, num_filters=num_filters, filter_size=filter_size, stride=stride, padding=(filter_size - 1) // 2, groups=groups, deformable_groups=1, im2col_step=1, param_attr=ParamAttr(name=_name + "_weights"), bias_attr=False, name=_name + ".conv2d.output.1") bn_name = self.na.fix_conv_norm_name(name) bn_name = self.prefix_name + bn_name if self.prefix_name != '' else bn_name norm_lr = 0. if self.freeze_norm else 1. norm_decay = self.norm_decay pattr = ParamAttr(name=bn_name + '_scale', learning_rate=norm_lr, regularizer=L2Decay(norm_decay)) battr = ParamAttr(name=bn_name + '_offset', learning_rate=norm_lr, regularizer=L2Decay(norm_decay)) if self.norm_type in ['bn', 'sync_bn']: global_stats = True if self.freeze_norm else False out = fluid.layers.batch_norm( input=conv, act=act, name=bn_name + '.output.1', param_attr=pattr, bias_attr=battr, moving_mean_name=bn_name + '_mean', moving_variance_name=bn_name + '_variance', use_global_stats=global_stats) scale = fluid.framework._get_var(pattr.name) bias = fluid.framework._get_var(battr.name) elif self.norm_type == 'affine_channel': scale = fluid.layers.create_parameter( shape=[conv.shape[1]], dtype=conv.dtype, attr=pattr, default_initializer=fluid.initializer.Constant(1.)) bias = fluid.layers.create_parameter( shape=[conv.shape[1]], dtype=conv.dtype, attr=battr, default_initializer=fluid.initializer.Constant(0.)) out = fluid.layers.affine_channel(x=conv, scale=scale, bias=bias, act=act) if self.freeze_norm: scale.stop_gradient = True bias.stop_gradient = True return out def _shortcut(self, input, ch_out, stride, is_first, name): max_pooling_in_short_cut = self.variant == 'd' ch_in = input.shape[1] # the naming rule is same as pretrained weight name = self.na.fix_shortcut_name(name) std_senet = getattr(self, 'std_senet', False) if ch_in != ch_out or stride != 1 or (self.depth < 50 and is_first): if std_senet: if is_first: return self._conv_norm(input, ch_out, 1, stride, name=name) else: return self._conv_norm(input, ch_out, 3, stride, name=name) if max_pooling_in_short_cut and not is_first: input = fluid.layers.pool2d( input=input, pool_size=2, pool_stride=2, pool_padding=0, ceil_mode=True, pool_type='avg') return self._conv_norm(input, ch_out, 1, 1, name=name) return self._conv_norm(input, ch_out, 1, stride, name=name) else: return input def bottleneck(self, input, num_filters, stride, is_first, name, dcn_v2=False): if self.variant == 'a': stride1, stride2 = stride, 1 else: stride1, stride2 = 1, stride # ResNeXt groups = getattr(self, 'groups', 1) group_width = getattr(self, 'group_width', -1) if groups == 1: expand = 4 elif (groups * group_width) == 256: expand = 1 else: # FIXME hard code for now, handles 32x4d, 64x4d and 32x8d num_filters = num_filters // 2 expand = 2 conv_name1, conv_name2, conv_name3, \ shortcut_name = self.na.fix_bottleneck_name(name) std_senet = getattr(self, 'std_senet', False) if std_senet: conv_def = [[int(num_filters / 2), 1, stride1, 'relu', 1, conv_name1], [num_filters, 3, stride2, 'relu', groups, conv_name2], [num_filters * expand, 1, 1, None, 1, conv_name3]] else: conv_def = [[num_filters, 1, stride1, 'relu', 1, conv_name1], [num_filters, 3, stride2, 'relu', groups, conv_name2], [num_filters * expand, 1, 1, None, 1, conv_name3]] residual = input for i, (c, k, s, act, g, _name) in enumerate(conv_def): residual = self._conv_norm( input=residual, num_filters=c, filter_size=k, stride=s, act=act, groups=g, name=_name, dcn_v2=(i == 1 and dcn_v2)) short = self._shortcut(input, num_filters * expand, stride, is_first=is_first, name=shortcut_name) # Squeeze-and-Excitation if callable(getattr(self, '_squeeze_excitation', None)): residual = self._squeeze_excitation(input=residual, num_channels=num_filters, name='fc' + name) return fluid.layers.elementwise_add(x=short, y=residual, act='relu', name=name + ".add.output.5") def basicblock(self, input, num_filters, stride, is_first, name, dcn_v2=False): assert dcn_v2 is False, "Not implemented yet." conv0 = self._conv_norm( input=input, num_filters=num_filters, filter_size=3, act='relu', stride=stride, name=name + "_branch2a") conv1 = self._conv_norm(input=conv0, num_filters=num_filters, filter_size=3, act=None, name=name + "_branch2b") short = self._shortcut(input, num_filters, stride, is_first, name=name + "_branch1") return fluid.layers.elementwise_add(x=short, y=conv1, act='relu') def layer_warp(self, input, stage_num): """ Args: input (Variable): input variable. stage_num (int): the stage number, should be 2, 3, 4, 5 Returns: The last variable in endpoint-th stage. """ assert stage_num in [2, 3, 4, 5] stages, block_func = self.depth_cfg[self.depth] count = stages[stage_num - 2] 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 # Make the layer name and parameter name consistent # with ImageNet pre-trained model conv = input for i in range(count): 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 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) # add non local model dim_in = conv.shape[1] 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)) return conv def c1_stage(self, input): out_chan = self._c1_out_chan_num conv1_name = self.na.fix_c1_stage_name() if self.variant in ['c', 'd']: conv_def = [ [out_chan // 2, 3, 2, "conv1_1"], [out_chan // 2, 3, 1, "conv1_2"], [out_chan, 3, 1, "conv1_3"], ] else: conv_def = [[out_chan, 7, 2, conv1_name]] for (c, k, s, _name) in conv_def: input = self._conv_norm(input=input, num_filters=c, filter_size=k, stride=s, act='relu', name=_name) output = fluid.layers.pool2d(input=input, pool_size=3, pool_stride=2, pool_padding=1, pool_type='max') return output def __call__(self, input): assert isinstance(input, Variable) assert not (set(self.feature_maps) - set([2, 3, 4, 5])), \ "feature maps {} not in [2, 3, 4, 5]".format(self.feature_maps) res_endpoints = [] res = input feature_maps = self.feature_maps severed_head = getattr(self, 'severed_head', False) if not severed_head: res = self.c1_stage(res) feature_maps = range(2, max(self.feature_maps) + 1) for i in feature_maps: res = self.layer_warp(res, i) if i in self.feature_maps: res_endpoints.append(res) if self.freeze_at >= i: res.stop_gradient = True if self.get_prediction: pool = fluid.layers.pool2d(input=res, pool_type='avg', global_pooling=True) stdv = 1.0 / math.sqrt(pool.shape[1] * 1.0) out = fluid.layers.fc( input=pool, size=self.class_dim, param_attr=fluid.param_attr.ParamAttr(initializer=fluid.initializer.Uniform(-stdv, stdv))) out = fluid.layers.softmax(out) return out return OrderedDict( [('res{}_sum'.format(self.feature_maps[idx]), feat) for idx, feat in enumerate(res_endpoints)]) class ResNetC5(ResNet): def __init__(self, depth=50, freeze_at=2, norm_type='affine_channel', freeze_norm=True, norm_decay=0., variant='b', feature_maps=[5], weight_prefix_name=''): super(ResNetC5, self).__init__(depth, freeze_at, norm_type, freeze_norm, norm_decay, variant, feature_maps) self.severed_head = True