POC serialization & deserialization

[xyao-nv]

Summary

A POC impl for EnvCfg serialization & deserialization, tested on non-Mimic, non-teleop envs.

High Level Design

• Serialization: Save the cfg after Arena composition, before gym.register() as Dict to dump into yaml
• Deserialization: Native load_yaml() from Lab is not usable because we have

1. Nested dict, containing func/class strings. Need to be converted as callables.
2. Dynamically added data fields, e.g. events / terminations / scenes
3. Default data fields are set to MISSING in configclass, which cannot be decoded automatically
4. Apart from EnvCfgTerms/Groups needed by gym API, we have IsaacLabArenaEnv configclass object

---

Data Flow Diagram

┌─────────────────┐
│   YAML File     │
└────────┬────────┘
         │
         ↓
┌────────────────────────────────────────────────────────┐
│ load_env_cfg_from_yaml()                               │
│                                                         │
│  1. Register YAML constructors (numpy, slice, etc.)    │
│  2. Load YAML → dict                                   │
│  3. Create base IsaacLabArenaManagerBasedRLEnvCfg      │
└────────┬───────────────────────────────────────────────┘
         │
         ↓
┌────────────────────────────────────────────────────────┐
│ Phase 1: Deserialize Sections                          │
│                                                         │
│  ├─ _create_scene_config(scene_dict)                   │
│  │   → cfg.scene (InteractiveSceneCfg + assets)        │
│  │                                                      │
│  ├─ _create_actions_config(actions_dict)               │
│  │   → cfg.actions (ActionsCfg + terms)                │
│  │                                                      │
│  ├─ _create_observations_config(obs_dict)              │
│  │   → cfg.observations (ObservationCfg + groups)      │
│  │                                                      │
│  ├─ _create_events_config(events_dict)                 │
│  │   → cfg.events (EventsCfg + terms)                  │
│  │                                                      │
│  ├─ _create_dynamic_manager_config(...)                │
│  │   → cfg.rewards, cfg.terminations, etc.             │
│  │                                                      │
│  └─ _reconstruct_metrics_from_yaml(metrics_list)       │
│      → cfg.metrics (List[MetricBase])                  │
└────────┬───────────────────────────────────────────────┘
         │
         ↓
┌────────────────────────────────────────────────────────┐
│ IsaacLabArenaManagerBasedRLEnvCfg                      │
│                                                         │
│  • cfg.scene (all assets merged)                       │
│  • cfg.actions (all action terms merged)               │
│  • cfg.observations (all obs terms merged)             │
│  • cfg.events, cfg.rewards, cfg.terminations, etc.     │
│  • cfg.metrics                                         │
│  • cfg.isaaclab_arena_env = None (not yet built)       │
└────────┬───────────────────────────────────────────────┘
         │
         ↓
┌────────────────────────────────────────────────────────┐
│ Phase 2: Reconstruct Arena Environment                 │
│                                                         │
│  _reconstruct_isaaclab_arena_env(arena_env_dict, cfg)  │
│                                                         │
│  ├─ reconstruct_embodiment(embodiment_dict, cfg)       │
│  │   • Extracts embodiment-specific configs            │
│  │   • Deserializes camera configs (with filtering)    │
│  │   → EmbodimentBase                                  │
│  │                                                      │
│  ├─ reconstruct_scene(scene_dict, cfg)                 │
│  │   • Pass 1: Creates Object, Background assets       │
│  │   • Pass 2: Creates ObjectReference assets          │
│  │   • Extracts scene-specific configs                 │
│  │   → Scene                                           │
│  │                                                      │
│  └─ reconstruct_task(task_dict, cfg)                   │
│      • Extracts task-specific configs                  │
│      → GenericTask                                     │
└────────┬───────────────────────────────────────────────┘
         │
         ↓
┌────────────────────────────────────────────────────────┐
│ cfg.isaaclab_arena_env                                 │
│                                                         │
│  IsaacLabArenaEnvironment(                             │
│    embodiment=EmbodimentBase(...),                     │
│    scene=Scene(assets=[...]),                          │
│    task=GenericTask(...)                               │
│  )                                                      │
└────────────────────────────────────────────────────────┘