Add resumable ScoNet skeleton training diagnostics

datasets/Scoliosis1K/README.md

@@ -75,6 +75,7 @@ The silhouette and skeleton-map pipelines are different experiments and should n
 
 * `Scoliosis1K-sil-pkl` is the silhouette modality used by the standard ScoNet configs.
 * pose-derived heatmap roots such as `Scoliosis1K_sigma_8.0/pkl` or DRF exports are skeleton-map inputs and require `in_channel: 2`.
+* DRF does **not** use the silhouette stream as an input. It uses `0_heatmap.pkl` plus `1_pav.pkl`.
 
 Naming note:
 
@@ -89,6 +90,18 @@ A strong silhouette checkpoint does not validate the skeleton-map path. In parti
 
 So if you are debugging DRF or `ScoNet-MT-ske` reproduction, do not use `ScoNet-20000-better.pt` as evidence that the heatmap preprocessing is correct.
 
+### Overlay caveat
+
+Do not treat a direct overlay between `Scoliosis1K-sil-pkl` and pose-derived skeleton maps as a valid alignment test.
+
+Reason:
+
+* the released silhouette modality is an estimated segmentation output from `PP-HumanSeg v2`
+* the released pose modality is an estimated keypoint output from `ViTPose`
+* the two modalities are normalized by different preprocessing pipelines before they reach OpenGait
+
+So a silhouette-vs-skeleton mismatch in a debug figure is usually a cross-modality frame-of-reference issue, not proof that the raw dataset is bad. The more important check for skeleton-map debugging is whether the **limb and joint channels align with each other** inside `0_heatmap.pkl`.
+
 ---
 
 ## Pose-to-Heatmap Conversion
@@ -146,6 +159,21 @@ If you explicitly want train-only PAV min-max statistics, add:
   --stats_partition=./datasets/Scoliosis1K/Scoliosis1K_118.json
 ```
 
+### Heatmap debugging notes
+
+Current confirmed findings from local debugging:
+
+* the raw pose dataset itself looks healthy; poor `ScoNet-MT-ske` results are not explained by obvious missing-joint collapse
+* a larger heatmap sigma can materially blur away the articulated structure; `sigma=8` was much broader than the silhouette geometry, while smaller sigma values recovered more structure
+* an earlier bug aligned the limb and joint channels separately; that made the two channels of `0_heatmap.pkl` slightly misregistered
+* the heatmap path is now patched so limb and joint channels share one alignment crop
+
+Remaining caution:
+
+* the exported skeleton map is stored as `64x64`
+* if the runtime config uses `BaseSilCuttingTransform`, the network actually sees `64x44`
+* that symmetric left/right crop is not automatically wrong, but it is still a meaningful ablation point for skeleton-map experiments
+
 The output layout is:
 
 ```text