From 2ea3b0f1ee4946ee8ad4454e9a871eef077b2d9d Mon Sep 17 00:00:00 2001
From: inter <inter@qq.com>
Date: Sun, 21 Sep 2025 20:18:56 +0800
Subject: [PATCH] Add File

---
 .../ffn/ddn_loss/ddn_loss.py                  | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 pcdet/models/backbones_3d/vfe/image_vfe_modules/ffn/ddn_loss/ddn_loss.py

diff --git a/pcdet/models/backbones_3d/vfe/image_vfe_modules/ffn/ddn_loss/ddn_loss.py b/pcdet/models/backbones_3d/vfe/image_vfe_modules/ffn/ddn_loss/ddn_loss.py
new file mode 100644
index 0000000..f59c11f
--- /dev/null
+++ b/pcdet/models/backbones_3d/vfe/image_vfe_modules/ffn/ddn_loss/ddn_loss.py
@@ -0,0 +1,75 @@
+import torch
+import torch.nn as nn
+
+
+from .balancer import Balancer
+from pcdet.utils import transform_utils
+
+try:
+    from kornia.losses.focal import FocalLoss
+except:
+    pass 
+    # print('Warning: kornia is not installed. This package is only required by CaDDN')
+
+    
+class DDNLoss(nn.Module):
+
+    def __init__(self,
+                 weight,
+                 alpha,
+                 gamma,
+                 disc_cfg,
+                 fg_weight,
+                 bg_weight,
+                 downsample_factor):
+        """
+        Initializes DDNLoss module
+        Args:
+            weight: float, Loss function weight
+            alpha: float, Alpha value for Focal Loss
+            gamma: float, Gamma value for Focal Loss
+            disc_cfg: dict, Depth discretiziation configuration
+            fg_weight: float, Foreground loss weight
+            bg_weight: float, Background loss weight
+            downsample_factor: int, Depth map downsample factor
+        """
+        super().__init__()
+        self.device = torch.cuda.current_device()
+        self.disc_cfg = disc_cfg
+        self.balancer = Balancer(downsample_factor=downsample_factor,
+                                 fg_weight=fg_weight,
+                                 bg_weight=bg_weight)
+
+        # Set loss function
+        self.alpha = alpha
+        self.gamma = gamma
+        self.loss_func = FocalLoss(alpha=self.alpha, gamma=self.gamma, reduction="none")
+        self.weight = weight
+
+    def forward(self, depth_logits, depth_maps, gt_boxes2d):
+        """
+        Gets DDN loss
+        Args:
+            depth_logits: (B, D+1, H, W), Predicted depth logits
+            depth_maps: (B, H, W), Depth map [m]
+            gt_boxes2d: torch.Tensor (B, N, 4), 2D box labels for foreground/background balancing
+        Returns:
+            loss: (1), Depth distribution network loss
+            tb_dict: dict[float], All losses to log in tensorboard
+        """
+        tb_dict = {}
+
+        # Bin depth map to create target
+        depth_target = transform_utils.bin_depths(depth_maps, **self.disc_cfg, target=True)
+
+        # Compute loss
+        loss = self.loss_func(depth_logits, depth_target)
+
+        # Compute foreground/background balancing
+        loss, tb_dict = self.balancer(loss=loss, gt_boxes2d=gt_boxes2d)
+
+        # Final loss
+        loss *= self.weight
+        tb_dict.update({"ddn_loss": loss.item()})
+
+        return loss, tb_dict