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# Multi-HMR
# Copyright (c) 2024-present NAVER Corp.
# CC BY-NC-SA 4.0 license
from typing import Callable, Optional
import torch
from torch import nn
from inspect import isfunction
from einops import rearrange
class AdaptiveLayerNorm1D(torch.nn.Module):
"""
Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/t_cond_mlp.py#L7
"""
def __init__(self, data_dim: int, norm_cond_dim: int):
super().__init__()
if data_dim <= 0:
raise ValueError(f"data_dim must be positive, but got {data_dim}")
if norm_cond_dim <= 0:
raise ValueError(f"norm_cond_dim must be positive, but got {norm_cond_dim}")
self.norm = torch.nn.LayerNorm(
data_dim
) # TODO: Check if elementwise_affine=True is correct
self.linear = torch.nn.Linear(norm_cond_dim, 2 * data_dim)
torch.nn.init.zeros_(self.linear.weight)
torch.nn.init.zeros_(self.linear.bias)
def forward(self, x: torch.Tensor, t: torch.Tensor) -> torch.Tensor:
# x: (batch, ..., data_dim)
# t: (batch, norm_cond_dim)
# return: (batch, data_dim)
x = self.norm(x)
alpha, beta = self.linear(t).chunk(2, dim=-1)
# Add singleton dimensions to alpha and beta
if x.dim() > 2:
alpha = alpha.view(alpha.shape[0], *([1] * (x.dim() - 2)), alpha.shape[1])
beta = beta.view(beta.shape[0], *([1] * (x.dim() - 2)), beta.shape[1])
return x * (1 + alpha) + beta
def normalization_layer(norm: Optional[str], dim: int, norm_cond_dim: int = -1):
"""
Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/t_cond_mlp.py#L48
"""
if norm == "batch":
return torch.nn.BatchNorm1d(dim)
elif norm == "layer":
return torch.nn.LayerNorm(dim)
elif norm == "ada":
assert norm_cond_dim > 0, f"norm_cond_dim must be positive, got {norm_cond_dim}"
return AdaptiveLayerNorm1D(dim, norm_cond_dim)
elif norm is None:
return torch.nn.Identity()
else:
raise ValueError(f"Unknown norm: {norm}")
def exists(val):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L17"
return val is not None
def default(val, d):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L21"
if exists(val):
return val
return d() if isfunction(d) else d
class PreNorm(nn.Module):
"""
Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L27
"""
def __init__(self, dim: int, fn: Callable, norm: str = "layer", norm_cond_dim: int = -1):
super().__init__()
self.norm = normalization_layer(norm, dim, norm_cond_dim)
self.fn = fn
def forward(self, x: torch.Tensor, *args, **kwargs):
if isinstance(self.norm, AdaptiveLayerNorm1D):
return self.fn(self.norm(x, *args), **kwargs)
else:
return self.fn(self.norm(x), **kwargs)
class FeedForward(nn.Module):
"""
Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L40
"""
def __init__(self, dim, hidden_dim, dropout=0.0):
super().__init__()
self.net = nn.Sequential(
nn.Linear(dim, hidden_dim),
nn.GELU(),
nn.Dropout(dropout),
nn.Linear(hidden_dim, dim),
nn.Dropout(dropout),
)
def forward(self, x):
return self.net(x)
class Attention(nn.Module):
"""
Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L55
"""
def __init__(self, dim, heads=8, dim_head=64, dropout=0.0):
super().__init__()
inner_dim = dim_head * heads
project_out = not (heads == 1 and dim_head == dim)
self.heads = heads
self.scale = dim_head**-0.5
self.attend = nn.Softmax(dim=-1)
self.dropout = nn.Dropout(dropout)
self.to_qkv = nn.Linear(dim, inner_dim * 3, bias=False)
self.to_out = (
nn.Sequential(nn.Linear(inner_dim, dim), nn.Dropout(dropout))
if project_out
else nn.Identity()
)
def forward(self, x, mask=None):
qkv = self.to_qkv(x).chunk(3, dim=-1)
# n --> the num query dimension
# TODO reshape b into b2 n and mask.
q, k, v = map(lambda t: rearrange(t, "b n (h d) -> b h n d", h=self.heads), qkv)
if mask is not None:
q, k, v = [x * mask[:, None, :, None] for x in [q, k, v]]
# q, k, v: [13:51:03.400365] torch.Size([22, 1, 256])
#q, k ,vk after reshape: torch.Size([16, 8, 1, 32])
dots = torch.matmul(q, k.transpose(-1, -2)) * self.scale
if mask is not None:
dots = dots - (1 - mask)[:, None, None, :] * 10e10
attn = self.attend(dots)
if mask is not None: # Just for good measure; this is probably overkill
attn = attn * mask[:, None, None, :]
attn = self.dropout(attn)
out = torch.matmul(attn, v)
# out shape :torch.Size([16, 8, 1, 32])
out = rearrange(out, "b h n d -> b n (h d)")
return self.to_out(out)
class CrossAttention(nn.Module):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L89"
def __init__(self, dim, context_dim=None, heads=8, dim_head=64, dropout=0.0):
super().__init__()
inner_dim = dim_head * heads
project_out = not (heads == 1 and dim_head == dim)
self.heads = heads
self.scale = dim_head**-0.5
self.attend = nn.Softmax(dim=-1)
self.dropout = nn.Dropout(dropout)
context_dim = default(context_dim, dim)
self.to_kv = nn.Linear(context_dim, inner_dim * 2, bias=False)
self.to_q = nn.Linear(dim, inner_dim, bias=False)
self.to_out = (
nn.Sequential(nn.Linear(inner_dim, dim), nn.Dropout(dropout))
if project_out
else nn.Identity()
)
def forward(self, x, context=None, mask=None):
context = default(context, x)
k, v = self.to_kv(context).chunk(2, dim=-1)
q = self.to_q(x)
q, k, v = map(lambda t: rearrange(t, "b n (h d) -> b h n d", h=self.heads), [q, k, v])
if mask is not None:
q = q * mask[:, None, :, None]
dots = torch.matmul(q, k.transpose(-1, -2)) * self.scale
if mask is not None:
dots = dots - (1 - mask).float()[:, None, :, None] * 1e6
attn = self.attend(dots)
attn = self.dropout(attn)
out = torch.matmul(attn, v)
if mask is not None: # Just for good measure; this is probably overkill
out = out * mask[:, None, :, None]
out = rearrange(out, "b h n d -> b n (h d)")
return self.to_out(out)
class TransformerCrossAttn(nn.Module):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L160"
def __init__(
self,
dim: int,
depth: int,
heads: int,
dim_head: int,
mlp_dim: int,
dropout: float = 0.0,
norm: str = "layer",
norm_cond_dim: int = -1,
context_dim: Optional[int] = None,
):
super().__init__()
self.layers = nn.ModuleList([])
for _ in range(depth):
sa = Attention(dim, heads=heads, dim_head=dim_head, dropout=dropout)
ca = CrossAttention(
dim, context_dim=context_dim, heads=heads, dim_head=dim_head, dropout=dropout
)
ff = FeedForward(dim, mlp_dim, dropout=dropout)
self.layers.append(
nn.ModuleList(
[
PreNorm(dim, sa, norm=norm, norm_cond_dim=norm_cond_dim),
PreNorm(dim, ca, norm=norm, norm_cond_dim=norm_cond_dim),
PreNorm(dim, ff, norm=norm, norm_cond_dim=norm_cond_dim),
]
)
)
def forward(self, x: torch.Tensor, *args, context=None, context_list=None, mask=None):
if context_list is None:
context_list = [context] * len(self.layers)
if len(context_list) != len(self.layers):
raise ValueError(f"len(context_list) != len(self.layers) ({len(context_list)} != {len(self.layers)})")
for i, (self_attn, cross_attn, ff) in enumerate(self.layers):
if mask is not None:
try:
x = x * mask[:, :, None]
except:
print("see ")
import pdb; pdb.set_trace()
x = self_attn(x, mask=mask, *args) + x
x = cross_attn(x, mask=mask, *args, context=context_list[i]) + x
x = ff(x, *args) + x
if mask is not None:
x = x * mask[:, :, None]
return x
class DropTokenDropout(nn.Module):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L204"
def __init__(self, p: float = 0.1):
super().__init__()
if p < 0 or p > 1:
raise ValueError(
"dropout probability has to be between 0 and 1, " "but got {}".format(p)
)
self.p = p
def forward(self, x: torch.Tensor):
# x: (batch_size, seq_len, dim)
if self.training and self.p > 0:
zero_mask = torch.full_like(x[0, :, 0], self.p).bernoulli().bool()
# TODO: permutation idx for each batch using torch.argsort
if zero_mask.any():
x = x[:, ~zero_mask, :]
return x
class ZeroTokenDropout(nn.Module):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L223"
def __init__(self, p: float = 0.1):
super().__init__()
if p < 0 or p > 1:
raise ValueError(
"dropout probability has to be between 0 and 1, " "but got {}".format(p)
)
self.p = p
def forward(self, x: torch.Tensor):
# x: (batch_size, seq_len, dim)
if self.training and self.p > 0:
zero_mask = torch.full_like(x[:, :, 0], self.p).bernoulli().bool()
# Zero-out the masked tokens
x[zero_mask, :] = 0
return x
class TransformerDecoder(nn.Module):
"Code modified from https://github.com/shubham-goel/4D-Humans/blob/a0def798c7eac811a63c8220fcc22d983b39785e/hmr2/models/components/pose_transformer.py#L301"
def __init__(
self,
num_tokens: int,
token_dim: int,
dim: int,
depth: int,
heads: int,
mlp_dim: int,
dim_head: int = 64,
dropout: float = 0.0,
emb_dropout: float = 0.0,
emb_dropout_type: str = 'drop',
norm: str = "layer",
norm_cond_dim: int = -1,
context_dim: Optional[int] = None,
skip_token_embedding: bool = False,
):
super().__init__()
if not skip_token_embedding:
self.to_token_embedding = nn.Linear(token_dim, dim)
else:
self.to_token_embedding = nn.Identity()
if token_dim != dim:
raise ValueError(
f"token_dim ({token_dim}) != dim ({dim}) when skip_token_embedding is True"
)
self.pos_embedding = nn.Parameter(torch.randn(1, num_tokens, dim))
if emb_dropout_type == "drop":
self.dropout = DropTokenDropout(emb_dropout)
elif emb_dropout_type == "zero":
self.dropout = ZeroTokenDropout(emb_dropout)
elif emb_dropout_type == "normal":
self.dropout = nn.Dropout(emb_dropout)
self.transformer = TransformerCrossAttn(
dim,
depth,
heads,
dim_head,
mlp_dim,
dropout,
norm=norm,
norm_cond_dim=norm_cond_dim,
context_dim=context_dim,
)
def forward(self, inp: torch.Tensor, *args, context=None, context_list=None, mask=None):
x = self.to_token_embedding(inp)
b, n, _ = x.shape
x = self.dropout(x)
#x += self.pos_embedding[:, :n]
x += self.pos_embedding[:, 0][:, None, :] # For now, we don't wish to embed a position. We might in future versions though.
x = self.transformer(x, *args, context=context, context_list=context_list, mask=mask)
return x
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