Added transcrowd_gap

model/reverse_perspective.py

@@ -37,9 +37,8 @@ class PerspectiveEstimator(nn.Module):
     After all, it is reasonable to say that you see more when you look at
     faraway places.
 
-    This do imply that **we need to obtain a reasonably good feature extractor
-    from general images before training this submodule**. Hence, for now, we
-    prob. should work on transformer first.
+    The paper utilizes a unsupervised loss -- "row feature density" refers to
+    the density of features computed from ?
 
     :param input_shape: (N, C, H, W)
     :param conv_kernel_shape: Oriented as (H, W)
@@ -63,6 +62,8 @@ class PerspectiveEstimator(nn.Module):
         (_, _, height, width) = input_shape
 
         # Sanity checking
+        # [TODO] Maybe this is unnecessary, maybe we can automatically suggest new params,
+        # but right now let's just do this...
         (_conv_height, _conv_width) = (
             np.floor(
                 (height + 2 * conv_padding - conv_dilation * (conv_kernel_shape[0] - 1) - 1)
@@ -112,4 +113,5 @@ class PerspectiveEstimator(nn.Module):
 
         return out
 
+    # def unsupervised_loss(predictions, targets):
 

model/transcrowd_gap.py

@@ -0,0 +1,76 @@
+r"""Transformer-encoder-regressor, adapted for reverse-perspective network.
+
+This model is identical to the *TransCrowd* [#]_ model, which we use for the
+subproblem of actually counting the heads in each *transformed* raw image.
+
+.. [#] Liang, D., Chen, X., Xu, W., Zhou, Y., & Bai, X. (2022).
+   Transcrowd: weakly-supervised crowd counting with transformers.
+   Science China Information Sciences, 65(6), 160104.
+"""
+from functools import partial
+
+import numpy as np
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+# The original paper uses timm to create and import/export custom models,
+# so we follow suit
+from timm.models.vision_transformer import VisionTransformer, _cfg
+from timm.models.registry import register_model
+from timm.models.layers import trunc_normal_
+
+class VisionTransformer_GAP(VisionTransformer):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        num_patches = self.patch_embed.num_patches
+
+        # That {p_1, p_2, ..., p_N} pos embedding
+        self.pos_embed = nn.Parameter(
+            torch.zeros(1, num_patches + 1, self.embed_dim)
+        )
+        # Fill self.pos_embed with N(0, 1) truncated to |0.2 * std|.
+        trunc_normal_(self.pos_embed, std=.02)
+
+        # The "regression head" (I think? [XXX])
+        self.output1 = nn.ModuleDict({
+            "output1.relu0": nn.ReLU(),
+            "output1.linear0": nn.Linear(in_features=6912 * 4, out_features=128),
+            "output1.relu1": nn.ReLU(),
+            "output1.dropout0": nn.Dropout(p=0.5),
+            "output1.linear1": nn.Linear(in_features=128, out_features=1),
+        })
+        self.output1.apply(self._init_weights)
+
+    def forward_features(self, x):
+        B = x.shape[0]
+        x = self.patch_embed(x)
+
+        # [XXX] Why do we need class token here? (ref. prev papers)
+        cls_tokens = self.cls_token.expand(B, -1, -1)
+        x = torch.cat((cls_tokens, x), dim=1) # Concatenate along j
+
+        # 3.2 Patch embedding
+        x = x + self.pos_embed
+        x = self.pos_drop(x)    # [XXX] Drop some patches out -- or not?
+
+        # 3.3 Transformer-encoder
+        for block in self.blocks:
+            x = block(x)
+
+        # [TODO] Interpret
+        x = self.norm(x)
+
+        x = x[:, 1:]
+
+        return x
+
+    def forward(self, x):
+        x = self.forward_features(x)
+        x = F.adaptive_avg_pool1d(x, (48))
+        x = x.view(x.shape[0], -1)
+        x = self.output1(x)
+        return x
+
+
+