4.0 KiB
ADR 0021: separate native scans, normalized scans and rolling local maps
Status: accepted Date: 2026-07-25
Context
Public autonomous-driving and field-robotics dataset viewers commonly display
one LiDAR revolution. Fixed-channel rotating sensors therefore produce the
familiar sparse rings. The current XGRIDS K1 MQTT lio_pcl evidence is a
different product: firmware evidence places it after LIO/modeling, and the
field-review UI accumulates multiple already registered increments in the map
frame.
Point count alone does not make these representations comparable. A cloud can be sparse per publication and still look dense after several seconds of pose registration. Conversely, voxel downsampling does not restore timing, scan lines or raw sensor geometry that the source no longer carries.
Patchwork++ is a ground classifier. It does not decode sensor packets, deskew
motion distortion, estimate pose, stabilize a rolling map or remove ghosts
from stale/dynamic observations. A successful Patchwork++ call against
lio_pcl remains diagnostic and does not repair the input domain.
Decision
Mission Core defines three non-interchangeable LiDAR products:
native-scan: one losslessly decoded source scan/frame with its native point-aligned fields and labels. It is never accumulated.normalized-scan: one sensor-frame scan after an explicit transform, deskew and bounded cleanup profile. Every transformation retains source identity and point alignment.rolling-local-map: normalized scans registered by pose into a bounded local map with explicit TTL, voxel deduplication and dynamic-point policy.
The Dataset Gateway is the first producer of this contract. GOOSE 3D is the
first admitted source because it publishes off-road point-wise semantic and
instance labels in SemanticKITTI-compatible XYZI + uint32 label files. Its
annotated point-cloud file represents one LiDAR revolution.
The gateway:
- preserves the native GOOSE frame before adaptation;
- never transforms labels independently of their points;
- does not assume a coordinate convention, mounting transform or sensor height unless source metadata supplies it;
- refuses automatic downloads of large archives;
- admits storage only under
D:\NDC_MISSIONCORE\datasetsor its WSL mirror; - never promotes K1
lio_pcltonative-scan.
The normalized pipeline is:
native packet/source frame
-> decode + calibration
-> per-point-time deskew
-> range/self/outlier/voxel policy
-> normalized-scan
-> ground/object inference
-> pose registration + TTL + voxel deduplication
-> rolling-local-map
Deskew is conditional: it requires per-point time plus synchronized IMU or odometry. If those fields are missing, the gateway reports the stage as unavailable rather than inventing timestamps.
Consequences
- The UI must label accumulated K1 evidence as a map product, not a scan.
- Dataset and device inputs can share downstream algorithms only after their normalized contracts match.
- Sensor adaptation may change range, FOV, point density, noise and dropout for robustness experiments, but it cannot recreate lost timestamps, occlusions or material response.
- Patchwork++ becomes eligible for a real quality gate only on a sensor-centric scan with declared scan geometry and physical mounting height plus independent labels.
- Stable operator visualization is owned by rolling-map policy, not by the ground classifier.