a42-proto

📦 A42 Protobuf Bindings (a42-proto)

Dieses Python-Paket enthält die Protobuf-Bindings für Sensordaten im A42-Format. Es erlaubt das einfache Einlesen und Verarbeiten von LiDAR-Scans und zugehörigen Objektinformationen.

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🔽 Datendownload

👉 KIT Sync & Share Download

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📥 Installation

pip install a42-proto

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🧪 Beispielskripte

• analyze_proto.py – aggregierte Auswertung über Frames, Scans, Punkte, Objekte
• visualize_pointcloud.py – zeigt eine Punktwolke in Open3D

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📄 Data Structure

Frame

• frame_timestamp_ns – global timestamp in nanoseconds
• lidars[] – list of LidarScan messages
• frame_id - unique identifier for the frame

Example:

first_scan = frame.lidars[0]

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LidarScan

• laser_name – sensor identifier (LaserName enum)
• scan_timestamp_ns – timestamp of this scan (ns)
• pointcloud – LiDAR point cloud (PointCloud)
• calibration – sensor calibration (SensorCalibration)
• object_list[] – detected objects (ObjectBBox)

Example:

objects = scan.object_list[0]

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PointCloud

All fields are stored as byte arrays and must be decoded into NumPy arrays.

• cartesian – XYZ coordinates (float32, shape N×3)
• intensity – intensity values (uint16)
• ambient – ambient light / signal quality (uint16)
• velocity – point-wise velocity (float32)
• reflectivity – reflectivity values (uint16)
• timestamp_offset – per‑point timestamp offset (uint64 ns)
• channel_id – channel index (uint16)

Example decoding:

import numpy as np
xyz = np.frombuffer(pc.cartesian, dtype=np.float32).reshape(-1, 3)
intensity = np.frombuffer(pc.intensity, dtype=np.uint16)

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ObjectBBox

• id – object ID
• timestamp_ns – timestamp of the object (ns)
• position {x,y,z} – center position
• dimension {x,y,z} – object size
• orientation {x,y,z,w} – quaternion orientation
• velocity {x,y,z} – velocity vector
• pointcloud – sub‑pointcloud inside the bounding box
• obj_class – semantic class
• obj_class_score – classification confidence

Example:

pos = obj.position

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SensorCalibration

• sensor_name – sensor identifier
• extrinsic[] – 4×4 row‑major extrinsic matrix
• vertical_fov, horizontal_fov – field of view
• vertical_scanlines, horizontal_scanlines – resolution
• horizontal_angle_spacing – angle spacing (deg)
• beam_altitude_angles[] – altitude angles
• beam_azimuth_angles[] – azimuth angles
• frame_mode – scan mode
• scan_pattern – scan pattern identifier

Example:

vfov = scan.calibration.vertical_fov

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