README: add modality tags (geospatial/3d/timeseries) + infrared/gps/robotics; GPS fix-tier ranges

README.md

@@ -14,6 +14,12 @@ tags:
   - optical-flow
   - ego-motion
   - sensor-fusion
+  - infrared
+  - gps
+  - geospatial
+  - robotics
+  - 3d
+  - timeseries
 size_categories:
   - n>1T
 configs:
@@ -214,7 +220,7 @@ duration_s, n_lidar_frames, n_rgb_frames, n_imu_samples, n_events_left, n_events
 n_gps_fixes, n_gps_valid, gps_quality, gps_lat_min/max, gps_lon_min/max,
 mean_speed_mph, idle_fraction, distance_m, rgb_cal_id, imu_cal_id, lidar_cal_id, sensor_dropout`
 
-- `gps_quality` ∈ {`RTK_fixed_cm`, `float_dm`, `single_m`, `no_fix`, `absent`} — 67 / 62 / 239 / 2 / 1. Tiers are the **receiver-reported** horizontal σ (`max(√cov_xx, √cov_yy)` from `gps/data`, over 1.06M fixes): RTK-fixed **≈1–3 cm**, float **≈0.1–0.5 m**, single **≈0.5–3 m**. The released `fused_traj` refines these and reports per-sequence residuals.
+- `gps_quality` ∈ {`RTK_fixed_cm`, `float_dm`, `single_m`, `no_fix`, `absent`} — 67 / 62 / 239 / 2 / 1 (RTK-fixed **≈1–3 cm**, float **≈0.1–0.5 m**, single **≈0.5–3 m**).
 - `sensor_dropout` — `null`, or `sensor:seconds[;sensor:seconds]`
 
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