Schema and Parsing Conventions

A loader that ignores any of these silently corrupts data:

• Quaternion order (w,x,y,z) in CSV vs (x,y,z,w) in ROS — read positionally.
• px4_gps.csv header has a trailing empty token: 11 header tokens, 10 data columns.
• rtk_gps{1,2}_data_revised.csv are headerless, 7 columns (v_x,v_y,v_z, not the README-advertised x,y,z).
• ground_truth/px4_imu_data.csv is headerless (drops the first sample if read header-inferred).
• Camera-calibration YAMLs have duplicate top-level keys rs_cam0/rs_cam1 (lose intrinsics under naive load).
• T_pximu_rsimu rows are whitespace-tokenized (no intra-row commas); T_pximu_lsimu/T_pximu_rsimu rotations are reduced-precision (re-orthonormalize).
• rs_odom/mocap headers have a space after each comma — strip column names.
• Image t[ns] is floating-point seconds, not nanoseconds.
  • #img_no is a 1-based index.
  • stereo pairs share an identical t[ns] (disambiguate by _c1/_c2, not timestamp).
  • Stereo _c1/_c2 counts are not guaranteed equal — a few unpaired leading/trailing singleton (mono) frames occur on indoor_* and several Mars runs (indoor_1 9495 c1 / 9492 c2, mars_18 7682 / 7673; the three transition_* are balanced by timestamp rows), so pair by _c1/_c2 + equal t[ns], never by index or odd/even position.
  • Balanced timestamp rows still do not guarantee usable files: the three transition runs contain referenced stereo pairs that are absent on disk (Known Defects).
• No NaN sentinels in extraction: invalid LRF reads (high and low), no-fix GPS, zero magnetic vectors, and dropped UWB anchors pass through as literal numbers; only RealSense odometry and the no-fix GPS placeholder use explicit markers (NaN / the 1.84e13 cov / lat==0).
• Support/_data/_revised files are time-supersets, crops, swapped, or re-timed variants — none substitutes for its primary file.
• Timestamp-pathology inventory (handle generically via the Time and Clocks “file order is authoritative” rule; this list is the audited footprint, not an oracle):
  • duplicate consecutive timestamps — px4_rpm on indoor_1/indoor_2 (1 s buckets), nav-cam t[ns] on every Mars run with imagery except mars_1, and same-lane stereo rows by design (each _c1/_c2 pair shares one t[ns]).
  • backward t steps — rs_odom mars_2 (1) and rs_odom_data mars_4 (1), and stereo t[ns] on indoor_3 (1), mars_8 (3), mars_9 (2), mars_10 (3), mars_11 (2), mars_12 (1), mars_13 (8), mars_14 (4), mars_16 (2), mars_19 (1).