refactor: Use linspace(-1,1) directly for coords

Simplify coordinate initialization by generating [-1,1] range directly
instead of [0,1] then normalizing. Mathematically equivalent, clearer.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/training/train_cnn.py b/training/train_cnn.py
index 5ad922e..1ea42a3 100755
--- a/training/train_cnn.py
+++ b/training/train_cnn.py
@@ -249,11 +249,9 @@ class SimpleCNN(nn.Module):
         # Normalize RGBD to [-1,1]
         x_norm = (x - 0.5) * 2.0
 
-        # Compute coordinates [0,1] then normalize to [-1,1]
-        y_coords = torch.linspace(0, 1, H, device=x.device).view(1,1,H,1).expand(B,1,H,W)
-        x_coords = torch.linspace(0, 1, W, device=x.device).view(1,1,1,W).expand(B,1,H,W)
-        y_coords = (y_coords - 0.5) * 2.0  # [-1,1]
-        x_coords = (x_coords - 0.5) * 2.0  # [-1,1]
+        # Compute normalized coordinates [-1,1]
+        y_coords = torch.linspace(-1, 1, H, device=x.device).view(1,1,H,1).expand(B,1,H,W)
+        x_coords = torch.linspace(-1, 1, W, device=x.device).view(1,1,1,W).expand(B,1,H,W)
 
         # Compute grayscale from original RGB (Rec.709) and normalize to [-1,1]
         gray = 0.2126*x[:,0:1] + 0.7152*x[:,1:2] + 0.0722*x[:,2:3]  # [B,1,H,W] in [0,1]