feat(scenegraph): add basic scene graph data structures

mini-nav/scenegraph/__init__.py

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+"""Scenegraph public API.
+
+This module exports the main scenegraph objects for easy import:
+
+from mini_nav.scenegraph import SimpleSceneGraph, RoomNode, ObjectNode
+"""
+
+from .objectnode import ObjectNode
+from .roomnode import RoomNode
+from .scenegraph import SimpleSceneGraph
+
+__all__ = ["ObjectNode", "RoomNode", "SimpleSceneGraph"]

mini-nav/scenegraph/objectnode.py

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+from dataclasses import dataclass
+
+import numpy as np
+
+
+# --- 1. 物品节点：极其扁平，只存“当前最新/平均”状态 ---
+@dataclass
+class ObjectNode:
+    obj_id: str  # 唯一ID (例如: "obj_001")
+    obj_id: str  # 唯一ID (例如: "obj_001")
+    room_id: str  # 所属房间的直接外键，不搞复杂的层级关系
+
+    # 位置：在 debug 阶段，一切认准全局坐标，不要搞局部坐标系
+    position: np.ndarray  # [x, y, z] 世界坐标系下的中心点或锚点
+
+    # 特征：直接存你压缩后的 512bit 结果，不搞历史缓存
+    visual_hash: np.ndarray  # 512bit 视觉特征 (用于外观检索)
+    semantic_hash: np.ndarray  # 512bit 语义特征 (用于类别对齐)
+
+    # Debug 必备：极简的生命周期管理，防止满屏“幽灵节点”
+    hit_count: int = 1  # 被观测到的次数。太低的可以直接过滤掉
+    last_seen_frame: int = 0  # 最后一次看到的帧号或时间戳

mini-nav/scenegraph/roomnode.py

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+from dataclasses import dataclass
+
+import numpy as np
+
+
+@dataclass
+class RoomNode:
+    room_id: str  # 例如: "room_A"
+
+    # 范围：不用复杂的 Polygon，用一个中心点+半径，或者简单的 3D BBox 足够了
+    center: np.ndarray  # [x, y, z]
+    bbox_extent: np.ndarray  # [dx, dy, dz] 用于快速判断一个点在不在房间里

mini-nav/scenegraph/scenegraph.py

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+from dataclasses import dataclass, field
+
+from .roomnode import RoomNode
+from .objectnode import ObjectNode
+
+
+@dataclass
+class SimpleSceneGraph:
+    rooms: dict[str, RoomNode] = field(default_factory=dict)
+    objects: dict[str, ObjectNode] = field(default_factory=dict)