3D Object Detection for Physical AI Applications

3D Object Detection for Physical AI Applications A robot needs more than image classification. It needs to know: What object is present? Where is it? How large is it? How is it oriented? 3D object detection answers these questions in physical space. 3D Detection Pipeline Camera / LiDAR | v Preprocessing | v Feature Extraction | v 3D Detection Model | v 3D Bounding Boxes | v Tracking / Planning A 3D bounding box can contain: (x, y, z) (width, height, depth) (rotation) (class) (confidence) LiDAR-Based Detection LiDAR naturally provides 3D geometry. A typical pipeline is: Point Cloud | v Filtering | v Voxelization / Features | v Neural Network | v 3D Boxes Challenges include sparse points and computational cost. Camera-Based Detection A camera provides dense visual information. Monocular 3D detection tries to infer depth from a single image, while stereo systems can estimate depth geometrically. Multi-Modal Detection Combining cameras and LiDAR can provide both semantics and geometry: Camera ---> Visual Features --+ | LiDAR ----> 3D Features ------+--> Fusion --> 3D Detection This is useful for autonomous robots operating around people, vehicles, and objects. Post-Processing Raw detections are often filtered using: Confidence thresholds Non-maximum suppression Geometric constraints Temporal tracking Tracking can stabilize detections across frames. ROS 2 Integration A practical architecture: /sensors/camera /sensors/lidar | v /3d_detector | v /objects_3d | +--> /tracker | +--> /planner Use standardized message structures where practical so perception remains decoupled from planning. Measuring Performance Evaluate: Precision Recall 3D IoU Position error Orientation error Inference latency FPS For physical AI, latency matters almost as much as accuracy. A detector that is accurate but too slow can still be unsuitable for a moving robot. Production Considerations Test across: Day/night conditions Different sensor placements Partial occlusion Different object sizes Dynamic