# copyright (c) 2022 PaddlePaddle Authors. All Rights Reserve. # 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. import math import paddle import paddle.nn as nn import paddle.nn.functional as F import numpy as np from paddle.nn.initializer import Constant from ppdet.modeling.shape_spec import ShapeSpec from ppdet.core.workspace import register, serializable from .transformer_utils import zeros_, DropPath, Identity class Mlp(nn.Layer): def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.): super().__init__() out_features = out_features or in_features hidden_features = hidden_features or in_features self.fc1 = nn.Linear(in_features, hidden_features) self.act = act_layer() self.fc2 = nn.Linear(hidden_features, out_features) self.drop = nn.Dropout(drop) def forward(self, x): x = self.fc1(x) x = self.act(x) x = self.drop(x) x = self.fc2(x) x = self.drop(x) return x class Attention(nn.Layer): def __init__(self, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0., window_size=None): super().__init__() self.num_heads = num_heads head_dim = dim // num_heads self.scale = qk_scale or head_dim**-0.5 self.qkv = nn.Linear(dim, dim * 3, bias_attr=False) if qkv_bias: self.q_bias = self.create_parameter( shape=([dim]), default_initializer=zeros_) self.v_bias = self.create_parameter( shape=([dim]), default_initializer=zeros_) else: self.q_bias = None self.v_bias = None if window_size: self.window_size = window_size self.num_relative_distance = (2 * window_size[0] - 1) * ( 2 * window_size[1] - 1) + 3 self.relative_position_bias_table = self.create_parameter( shape=(self.num_relative_distance, num_heads), default_initializer=zeros_) # 2*Wh-1 * 2*Ww-1, nH # cls to token & token 2 cls & cls to cls # get pair-wise relative position index for each token inside the window coords_h = paddle.arange(window_size[0]) coords_w = paddle.arange(window_size[1]) coords = paddle.stack(paddle.meshgrid( [coords_h, coords_w])) # 2, Wh, Ww coords_flatten = paddle.flatten(coords, 1) # 2, Wh*Ww coords_flatten_1 = paddle.unsqueeze(coords_flatten, 2) coords_flatten_2 = paddle.unsqueeze(coords_flatten, 1) relative_coords = coords_flatten_1.clone() - coords_flatten_2.clone( ) #relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Wh relative_coords = relative_coords.transpose( (1, 2, 0)) #.contiguous() # Wh*Ww, Wh*Ww, 2 relative_coords[:, :, 0] += window_size[ 0] - 1 # shift to start from 0 relative_coords[:, :, 1] += window_size[1] - 1 relative_coords[:, :, 0] *= 2 * window_size[1] - 1 relative_position_index = \ paddle.zeros(shape=(window_size[0] * window_size[1] + 1, ) * 2, dtype=relative_coords.dtype) relative_position_index[1:, 1:] = relative_coords.sum( -1) # Wh*Ww, Wh*Ww relative_position_index[0, 0:] = self.num_relative_distance - 3 relative_position_index[0:, 0] = self.num_relative_distance - 2 relative_position_index[0, 0] = self.num_relative_distance - 1 self.register_buffer("relative_position_index", relative_position_index) # trunc_normal_(self.relative_position_bias_table, std=.0) else: self.window_size = None self.relative_position_bias_table = None self.relative_position_index = None self.attn_drop = nn.Dropout(attn_drop) self.proj = nn.Linear(dim, dim) self.proj_drop = nn.Dropout(proj_drop) def forward(self, x, rel_pos_bias=None): x_shape = paddle.shape(x) N, C = x_shape[1], x_shape[2] qkv_bias = None if self.q_bias is not None: qkv_bias = paddle.concat( (self.q_bias, paddle.zeros_like(self.v_bias), self.v_bias)) qkv = F.linear(x, weight=self.qkv.weight, bias=qkv_bias) qkv = qkv.reshape((-1, N, 3, self.num_heads, C // self.num_heads)).transpose((2, 0, 3, 1, 4)) q, k, v = qkv[0], qkv[1], qkv[2] attn = (q.matmul(k.transpose((0, 1, 3, 2)))) * self.scale if self.relative_position_bias_table is not None: relative_position_bias = self.relative_position_bias_table[ self.relative_position_index.reshape([-1])].reshape([ self.window_size[0] * self.window_size[1] + 1, self.window_size[0] * self.window_size[1] + 1, -1 ]) # Wh*Ww,Wh*Ww,nH relative_position_bias = relative_position_bias.transpose( (2, 0, 1)) #.contiguous() # nH, Wh*Ww, Wh*Ww attn = attn + relative_position_bias.unsqueeze(0) if rel_pos_bias is not None: attn = attn + rel_pos_bias attn = nn.functional.softmax(attn, axis=-1) attn = self.attn_drop(attn) x = (attn.matmul(v)).transpose((0, 2, 1, 3)).reshape((-1, N, C)) x = self.proj(x) x = self.proj_drop(x) return x class Block(nn.Layer): def __init__(self, dim, num_heads, mlp_ratio=4., qkv_bias=False, qk_scale=None, drop=0., attn_drop=0., drop_path=0., window_size=None, init_values=None, act_layer=nn.GELU, norm_layer='nn.LayerNorm', epsilon=1e-5): super().__init__() self.norm1 = nn.LayerNorm(dim, epsilon=1e-6) self.attn = Attention( dim, num_heads=num_heads, qkv_bias=qkv_bias, qk_scale=qk_scale, attn_drop=attn_drop, proj_drop=drop, window_size=window_size) # NOTE: drop path for stochastic depth, we shall see if this is better than dropout here self.drop_path = DropPath(drop_path) if drop_path > 0. else Identity() self.norm2 = eval(norm_layer)(dim, epsilon=epsilon) mlp_hidden_dim = int(dim * mlp_ratio) self.mlp = Mlp(in_features=dim, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop) if init_values is not None: self.gamma_1 = self.create_parameter( shape=([dim]), default_initializer=Constant(value=init_values)) self.gamma_2 = self.create_parameter( shape=([dim]), default_initializer=Constant(value=init_values)) else: self.gamma_1, self.gamma_2 = None, None def forward(self, x, rel_pos_bias=None): if self.gamma_1 is None: x = x + self.drop_path( self.attn( self.norm1(x), rel_pos_bias=rel_pos_bias)) x = x + self.drop_path(self.mlp(self.norm2(x))) else: x = x + self.drop_path(self.gamma_1 * self.attn( self.norm1(x), rel_pos_bias=rel_pos_bias)) x = x + self.drop_path(self.gamma_2 * self.mlp(self.norm2(x))) return x class PatchEmbed(nn.Layer): """ Image to Patch Embedding """ def __init__(self, img_size=[224, 224], patch_size=16, in_chans=3, embed_dim=768): super().__init__() self.num_patches_w = img_size[0] // patch_size self.num_patches_h = img_size[1] // patch_size num_patches = self.num_patches_w * self.num_patches_h self.patch_shape = (img_size[0] // patch_size, img_size[1] // patch_size) self.img_size = img_size self.patch_size = patch_size self.num_patches = num_patches self.proj = nn.Conv2D( in_chans, embed_dim, kernel_size=patch_size, stride=patch_size) @property def num_patches_in_h(self): return self.img_size[1] // self.patch_size @property def num_patches_in_w(self): return self.img_size[0] // self.patch_size def forward(self, x, mask=None): B, C, H, W = x.shape return self.proj(x) class RelativePositionBias(nn.Layer): def __init__(self, window_size, num_heads): super().__init__() self.window_size = window_size self.num_relative_distance = (2 * window_size[0] - 1) * ( 2 * window_size[1] - 1) + 3 self.relative_position_bias_table = self.create_parameter( shape=(self.num_relative_distance, num_heads), default_initialize=zeros_) # cls to token & token 2 cls & cls to cls # get pair-wise relative position index for each token inside the window coords_h = paddle.arange(window_size[0]) coords_w = paddle.arange(window_size[1]) coords = paddle.stack(paddle.meshgrid( [coords_h, coords_w])) # 2, Wh, Ww coords_flatten = coords.flatten(1) # 2, Wh*Ww relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Ww relative_coords = relative_coords.transpos( (1, 2, 0)) # Wh*Ww, Wh*Ww, 2 relative_coords[:, :, 0] += window_size[0] - 1 # shift to start from 0 relative_coords[:, :, 1] += window_size[1] - 1 relative_coords[:, :, 0] *= 2 * window_size[1] - 1 relative_position_index = \ paddle.zeros(size=(window_size[0] * window_size[1] + 1,) * 2, dtype=relative_coords.dtype) relative_position_index[1:, 1:] = relative_coords.sum( -1) # Wh*Ww, Wh*Ww relative_position_index[0, 0:] = self.num_relative_distance - 3 relative_position_index[0:, 0] = self.num_relative_distance - 2 relative_position_index[0, 0] = self.num_relative_distance - 1 self.register_buffer("relative_position_index", relative_position_index) def forward(self): relative_position_bias = \ self.relative_position_bias_table[self.relative_position_index.view(-1)].view( self.window_size[0] * self.window_size[1] + 1, self.window_size[0] * self.window_size[1] + 1, -1) # Wh*Ww,Wh*Ww,nH return relative_position_bias.transpose((2, 0, 1)) # nH, Wh*Ww, Wh*Ww def get_sinusoid_encoding_table(n_position, d_hid, token=False): ''' Sinusoid position encoding table ''' def get_position_angle_vec(position): return [ position / np.power(10000, 2 * (hid_j // 2) / d_hid) for hid_j in range(d_hid) ] sinusoid_table = np.array( [get_position_angle_vec(pos_i) for pos_i in range(n_position)]) sinusoid_table[:, 0::2] = np.sin(sinusoid_table[:, 0::2]) # dim 2i sinusoid_table[:, 1::2] = np.cos(sinusoid_table[:, 1::2]) # dim 2i+1 if token: sinusoid_table = np.concatenate( [sinusoid_table, np.zeros([1, d_hid])], dim=0) return paddle.to_tensor(sinusoid_table, dtype=paddle.float32).unsqueeze(0) @register @serializable class VisionTransformer(nn.Layer): """ Vision Transformer with support for patch input """ def __init__(self, img_size=[672, 1092], patch_size=16, in_chans=3, embed_dim=768, depth=12, num_heads=12, mlp_ratio=4, qkv_bias=False, qk_scale=None, drop_rate=0., attn_drop_rate=0., drop_path_rate=0., norm_layer='nn.LayerNorm', init_values=None, use_rel_pos_bias=False, use_shared_rel_pos_bias=False, epsilon=1e-5, final_norm=False, pretrained=None, out_indices=[3, 5, 7, 11], use_abs_pos_emb=False, use_sincos_pos_emb=True, with_fpn=True, use_checkpoint=False, **args): super().__init__() self.img_size = img_size self.embed_dim = embed_dim self.with_fpn = with_fpn self.use_checkpoint = use_checkpoint self.use_sincos_pos_emb = use_sincos_pos_emb self.use_rel_pos_bias = use_rel_pos_bias self.final_norm = final_norm if use_checkpoint: paddle.seed(0) self.patch_embed = PatchEmbed( img_size=img_size, patch_size=patch_size, in_chans=in_chans, embed_dim=embed_dim) self.pos_w = self.patch_embed.num_patches_in_w self.pos_h = self.patch_embed.num_patches_in_h self.cls_token = self.create_parameter( shape=(1, 1, embed_dim), default_initializer=paddle.nn.initializer.Constant(value=0.)) if use_abs_pos_emb: self.pos_embed = self.create_parameter( shape=(1, self.pos_w * self.pos_h + 1, embed_dim), default_initializer=paddle.nn.initializer.TruncatedNormal( std=.02)) elif use_sincos_pos_emb: pos_embed = self.build_2d_sincos_position_embedding(embed_dim) self.pos_embed = pos_embed self.pos_embed = self.create_parameter(shape=pos_embed.shape) self.pos_embed.set_value(pos_embed.numpy()) self.pos_embed.stop_gradient = True else: self.pos_embed = None self.pos_drop = nn.Dropout(p=drop_rate) if use_shared_rel_pos_bias: self.rel_pos_bias = RelativePositionBias( window_size=self.patch_embed.patch_shape, num_heads=num_heads) else: self.rel_pos_bias = None dpr = np.linspace(0, drop_path_rate, depth) self.blocks = nn.LayerList([ Block( dim=embed_dim, num_heads=num_heads, mlp_ratio=mlp_ratio, qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[i], norm_layer=norm_layer, init_values=init_values, window_size=self.patch_embed.patch_shape if use_rel_pos_bias else None, epsilon=epsilon) for i in range(depth) ]) self.pretrained = pretrained self.init_weight() assert len(out_indices) <= 4, '' self.out_indices = out_indices self.out_channels = [embed_dim for _ in range(len(out_indices))] self.out_strides = [4, 8, 16, 32][-len(out_indices):] if with_fpn else [ 8 for _ in range(len(out_indices)) ] self.norm = Identity() if self.with_fpn: self.init_fpn( embed_dim=embed_dim, patch_size=patch_size, ) def init_weight(self): pretrained = self.pretrained if pretrained: if 'http' in pretrained: #URL path = paddle.utils.download.get_weights_path_from_url( pretrained) else: #model in local path path = pretrained load_state_dict = paddle.load(path) model_state_dict = self.state_dict() pos_embed_name = "pos_embed" if pos_embed_name in load_state_dict.keys(): load_pos_embed = paddle.to_tensor( load_state_dict[pos_embed_name], dtype="float32") if self.pos_embed.shape != load_pos_embed.shape: pos_size = int(math.sqrt(load_pos_embed.shape[1] - 1)) model_state_dict[pos_embed_name] = self.resize_pos_embed( load_pos_embed, (pos_size, pos_size), (self.pos_h, self.pos_w)) # self.set_state_dict(model_state_dict) load_state_dict[pos_embed_name] = model_state_dict[ pos_embed_name] print("Load pos_embed and resize it from {} to {} .".format( load_pos_embed.shape, self.pos_embed.shape)) self.set_state_dict(load_state_dict) print("Load load_state_dict....") def init_fpn(self, embed_dim=768, patch_size=16, out_with_norm=False): if patch_size == 16: self.fpn1 = nn.Sequential( nn.Conv2DTranspose( embed_dim, embed_dim, kernel_size=2, stride=2), nn.BatchNorm2D(embed_dim), nn.GELU(), nn.Conv2DTranspose( embed_dim, embed_dim, kernel_size=2, stride=2), ) self.fpn2 = nn.Sequential( nn.Conv2DTranspose( embed_dim, embed_dim, kernel_size=2, stride=2), ) self.fpn3 = Identity() self.fpn4 = nn.MaxPool2D(kernel_size=2, stride=2) elif patch_size == 8: self.fpn1 = nn.Sequential( nn.Conv2DTranspose( embed_dim, embed_dim, kernel_size=2, stride=2), ) self.fpn2 = Identity() self.fpn3 = nn.Sequential(nn.MaxPool2D(kernel_size=2, stride=2), ) self.fpn4 = nn.Sequential(nn.MaxPool2D(kernel_size=4, stride=4), ) if not out_with_norm: self.norm = Identity() else: self.norm = nn.LayerNorm(embed_dim, epsilon=1e-6) def interpolate_pos_encoding(self, x, w, h): npatch = x.shape[1] - 1 N = self.pos_embed.shape[1] - 1 w0 = w // self.patch_embed.patch_size h0 = h // self.patch_embed.patch_size if npatch == N and w0 == self.patch_embed.num_patches_w and h0 == self.patch_embed.num_patches_h: return self.pos_embed class_pos_embed = self.pos_embed[:, 0] patch_pos_embed = self.pos_embed[:, 1:] dim = x.shape[-1] # we add a small number to avoid floating point error in the interpolation # see discussion at https://github.com/facebookresearch/dino/issues/8 w0, h0 = w0 + 0.1, h0 + 0.1 patch_pos_embed = nn.functional.interpolate( patch_pos_embed.reshape([ 1, self.patch_embed.num_patches_w, self.patch_embed.num_patches_h, dim ]).transpose((0, 3, 1, 2)), scale_factor=(w0 / self.patch_embed.num_patches_w, h0 / self.patch_embed.num_patches_h), mode='bicubic', ) assert int(w0) == patch_pos_embed.shape[-2] and int( h0) == patch_pos_embed.shape[-1] patch_pos_embed = patch_pos_embed.transpose( (0, 2, 3, 1)).reshape([1, -1, dim]) return paddle.concat( (class_pos_embed.unsqueeze(0), patch_pos_embed), axis=1) def resize_pos_embed(self, pos_embed, old_hw, new_hw): """ Resize pos_embed weight. Args: pos_embed (Tensor): the pos_embed weight old_hw (list[int]): the height and width of old pos_embed new_hw (list[int]): the height and width of new pos_embed Returns: Tensor: the resized pos_embed weight """ cls_pos_embed = pos_embed[:, :1, :] pos_embed = pos_embed[:, 1:, :] pos_embed = pos_embed.transpose([0, 2, 1]) pos_embed = pos_embed.reshape([1, -1, old_hw[0], old_hw[1]]) pos_embed = F.interpolate( pos_embed, new_hw, mode='bicubic', align_corners=False) pos_embed = pos_embed.flatten(2).transpose([0, 2, 1]) pos_embed = paddle.concat([cls_pos_embed, pos_embed], axis=1) return pos_embed def build_2d_sincos_position_embedding( self, embed_dim=768, temperature=10000., ): h, w = self.patch_embed.patch_shape grid_w = paddle.arange(w, dtype=paddle.float32) grid_h = paddle.arange(h, dtype=paddle.float32) grid_w, grid_h = paddle.meshgrid(grid_w, grid_h) assert embed_dim % 4 == 0, 'Embed dimension must be divisible by 4 for 2D sin-cos position embedding' pos_dim = embed_dim // 4 omega = paddle.arange(pos_dim, dtype=paddle.float32) / pos_dim omega = 1. / (temperature**omega) out_w = grid_w.flatten()[..., None] @omega[None] out_h = grid_h.flatten()[..., None] @omega[None] pos_emb = paddle.concat( [ paddle.sin(out_w), paddle.cos(out_w), paddle.sin(out_h), paddle.cos(out_h) ], axis=1)[None, :, :] pe_token = paddle.zeros([1, 1, embed_dim], dtype=paddle.float32) pos_embed = paddle.concat([pe_token, pos_emb], axis=1) # pos_embed.stop_gradient = True return pos_embed def forward(self, x): x = x['image'] if isinstance(x, dict) else x _, _, h, w = x.shape x = self.patch_embed(x) B, D, Hp, Wp = x.shape # b * c * h * w cls_tokens = self.cls_token.expand( (B, self.cls_token.shape[-2], self.cls_token.shape[-1])) x = x.flatten(2).transpose([0, 2, 1]) # b * hw * c x = paddle.concat([cls_tokens, x], axis=1) if self.pos_embed is not None: # x = x + self.interpolate_pos_encoding(x, w, h) x = x + self.interpolate_pos_encoding(x, h, w) x = self.pos_drop(x) rel_pos_bias = self.rel_pos_bias( ) if self.rel_pos_bias is not None else None feats = [] for idx, blk in enumerate(self.blocks): if self.use_checkpoint and self.training: x = paddle.distributed.fleet.utils.recompute( blk, x, rel_pos_bias, **{"preserve_rng_state": True}) else: x = blk(x, rel_pos_bias) if idx in self.out_indices: xp = paddle.reshape( paddle.transpose( self.norm(x[:, 1:, :]), perm=[0, 2, 1]), shape=[B, D, Hp, Wp]) feats.append(xp) if self.with_fpn: fpns = [self.fpn1, self.fpn2, self.fpn3, self.fpn4] for i in range(len(feats)): feats[i] = fpns[i](feats[i]) return feats @property def num_layers(self): return len(self.blocks) @property def no_weight_decay(self): return {'pos_embed', 'cls_token'} @property def out_shape(self): return [ ShapeSpec( channels=c, stride=s) for c, s in zip(self.out_channels, self.out_strides) ]