docs(cnn_v3): add full Old House example to HOW_TO_CNN §1b

handoff(Gemini): added render + batch-pack example commands at end of section 1b

1 files changed, 23 insertions, 0 deletions

diff --git a/cnn_v3/docs/HOW_TO_CNN.md b/cnn_v3/docs/HOW_TO_CNN.md
index 69bbf6f..bb6f7a7 100644
--- a/cnn_v3/docs/HOW_TO_CNN.md
+++ b/cnn_v3/docs/HOW_TO_CNN.md
@@ -225,6 +225,29 @@ done
 - Alpha convention: Blender alpha=1 means opaque; `transp.png` inverts this (transp=0 opaque)
 - `Shadow` pass in Cycles must be explicitly enabled in Render Properties → Passes → Effects
 
+#### Full example (Old House scene, 2 frames)
+
+**Step 1 — Render:**
+```bash
+cd cnn_v3/training
+blender4 -b input_3d/"Old House 2 3D Models.blend" -P blender_export.py -- \
+    --output tmp/renders/frames \
+    --width 640 --height 360 \
+    --start-frame 1 --end-frame 2 \
+    --view-layer RenderLayer
+```
+
+**Step 2 — Pack:**
+```bash
+cd cnn_v3/training
+for exr in tmp/renders/frames/*.exr; do
+    name=$(basename "${exr%.exr}")
+    python3 pack_blender_sample.py \
+        --exr "$exr" \
+        --output dataset/full/sample_${name}/
+done
+```
+
 ---
 
 ### 1c. Dataset Layout