gps-denied-onboard/_docs/02_document/glossary.md

Glossary

Status: confirmed-by-user Date: 2026-05-09 Scope: project-specific terminology for the GPS-denied onboard pose-estimation system. Generic software / industry terms (REST, JSON, IMU, WGS84, etc.) are intentionally omitted.

Terms are alphabetical. Each entry: one-line definition + parenthetical source.

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adti20 — Informal name for the production deployment camera, the ADTi Surveyor Lite 20MP 20L V1 (APS-C ~23.6×15.7 mm, ~5472×3648 px, fixed downward, no gimbal). Pinned in restrictions.md §Cameras. (source: restrictions.md, user confirmation 2026-05-09)

adti26 — Informal name for the camera that captured the 60 still-image test fixtures (AD000001..AD000060.jpg) under _docs/00_problem/input_data/. Distinct from the production-deployed adti20; calibration data must be sourced from public/factory references for these test images. (source: user confirmation 2026-05-09)

AdHoP refinement — OrthoLoC method-agnostic perspective preconditioning, conditional sub-stage between cross-domain matcher and pose estimation; invoked only when initial reprojection error exceeds threshold (component C3.5). (source: solution.md §C3.5, SQ2 Decision 2)

AGL / Above Ground Level — Vertical distance from the ground directly below the UAV; operational ceiling ≤1 km AGL. (source: restrictions.md §UAV & Flight)

AI camera — Operator-controlled gimbal+zoom camera consumed by AI detection systems; out of scope for nav-pose, in scope for AC-7.x object localization only. (source: restrictions.md §Cameras)

Camera calibration artifact — JSON file carrying camera intrinsics + distortion + body-to-camera extrinsics + acquisition method (factory_sheet | checkerboard_refined | hybrid). The only way camera-specific parameters enter the system; no hard-coded camera math anywhere. Test fixtures and production deployments load different artifacts on the same code path. (source: user directive 2026-05-09)

Companion / Companion PC — The onboard Jetson Orin Nano Super running the GPS-denied estimation pipeline. Synonyms used interchangeably across docs. (source: restrictions.md §Onboard Hardware)

D-PROJ-1 — (CLOSED in this Plan cycle) Camera calibration acquisition strategy. Resolved as: hybrid factory data sheet + per-unit ground-truth checkerboard refinement (~1 day per deployed unit). No physical hardware available this cycle, so production calibration is documented as instructions only. (source: solution.md Open decisions, user confirmation 2026-05-09)

D-PROJ-2 — (OPEN, parent-suite) Two design tasks against satellite-provider: (i) post-landing tile ingest endpoint, (ii) multi-flight trust / staleness logic. Surfaced in satellite-provider/_docs/ outside this Plan cycle as a parent-suite deliverable. Tracked via _docs/_process_leftovers/2026-05-09_satellite-provider-design-tasks.md. (source: solution.md, user confirmation 2026-05-09)

D-PROJ-3 — Multi-flight fixture acquisition (AerialVL S03 + Maxar Open Data Ukraine + own multi-flight data). NOT pursued in this Plan cycle: AC-NEW-4 / AC-NEW-7 wording was relaxed to Monte-Carlo-over-current-data with stated CI; multi-flight statistical residual risk recorded for the Step 4 risk register. (source: solution.md, traceability-matrix.md, user confirmation 2026-05-09)

Dead reckoned — Source label dead_reckoned: estimate produced from IMU-only propagation with no visual or satellite anchoring. Carries monotonically growing covariance; emitted during visual blackouts or after re-localization fails. (source: AC-1.4, AC-NEW-8)

Derkachi flight footage — Representative cropped nadir video + synchronized SCALED_IMU2 + GLOBAL_POSITION_INT telemetry under input_data/flight_derkachi/. Used for runtime cadence + VIO + replay testing. (source: problem.md, data_parameters.md)

External position / GPS replacement — What this system emits to the FC: WGS84 coordinates + honest covariance + provenance label, replacing real GPS when denied/spoofed. (source: AC-4.3, AC-6.3)

FC / Flight Controller — ArduPilot Plane or iNav. PX4 explicitly out of scope. (source: restrictions.md §Sensors & Integration)

FDR / Flight Data Recorder — Per-flight onboard NVM record (≤64 GB) of estimates, IMU traces, MAVLink stream, mid-flight tiles, system health, failed-tile thumbnails. Excludes raw nav/AI-camera frames. (source: AC-NEW-3)

Flight — Operator-authored mission persisted in the parent-suite flights REST service. Carries an ordered list of Waypoint entries (lat / lon / alt / objective / source). The DTO shape mirrors suite/flights/Database/Entities/{Flight,Waypoint}.cs. C12 reads the Flight pre-flight to derive the cache bbox + takeoff origin (AZ-489); the companion never reaches the flights service. (source: ADR-010, AZ-489)

Flights API / flights REST service — Parent-suite .NET 8 REST microservice (suite/flights/) that owns Flight + Waypoint persistence. Read pre-flight by C12 FlightsApiClient over HTTPS. Operator-workstation-only — never reached from the airborne companion (Principle #9). (source: ADR-010, AZ-489)

Flight state — Boolean signal IN_AIR | ON_GROUND derived from FC MAV_STATE (MAVLink HEARTBEAT). Safety-critical: gates the post-landing upload path; IN_AIR forbids any outbound write to satellite-provider. Enforced primarily by process-level isolation — the Tile Manager (C11), which carries both the TileDownloader and the TileUploader, is not loaded in the airborne companion image. (source: user directive 2026-05-09)

GCS / Ground Control Station — QGroundControl. Mission Planner is out of scope. (source: restrictions.md)

GPS denial / GPS spoofing — Distinct failure modes the system must distinguish: denial = no fix; spoofing = false fix that must not be promoted into the estimator. (source: AC-3.5, AC-NEW-2, AC-NEW-8)

GPS_INPUT — MAVLink message used as the per-frame FC delivery channel for ArduPilot Plane. (source: AC-4.3, restrictions.md)

GSD / Ground Sample Distance — Meters-per-pixel on the ground; target 10–20 cm/px @ 1 km AGL for the nav camera. (source: restrictions.md §Cameras)

Internal smoothing — AC-4.5 scope: GTSAM iSAM2 retroactively refines past keyframes onboard and emits the corrected current frame; the FC log is forward-time only. NOT to be confused with FC-side retroactive correction (which neither ArduPilot nor iNav supports). (source: solution.md §C5, Mode B Fact #107)

Jetson Orin Nano Super — Pinned companion compute: 67 TOPS sparse INT8, 8 GB shared LPDDR5, 25 W TDP, JetPack/CUDA/TensorRT. (source: restrictions.md)

Mid-flight bounded-delta GPS gate — Third clause of Principle #11. Even when FC GPS health is "stable + non-spoofed for ≥ 10 s" and the visual/satellite consistency check has succeeded, the FC's reported position must be within ≤ 200 m (configurable) of the companion's last emitted PoseEstimate before the FC GPS is fused via add_pose_anchor. Catches "FC reports stable GPS but the value is wrong". (source: Principle #11 amended, ADR-010)

Mid-flight tile generation — Companion orthorectifies nav-camera frames into basemap-projected tiles in flight, deduplicates, stores locally in satellite-provider-compatible format. NO outbound upload while airborne — upload happens post-landing only. (source: AC-8.4, user directive 2026-05-09)

Mission Planner UI — Parent-suite operator-facing web UI at suite/ui/ where operators author flight routes (waypoints + altitudes + objectives) before C12 cache provisioning. Persists routes to the flights REST service. Out of scope for this project's deliverables, but the Flight DTO it produces IS in scope as an inbound boundary. Not to be confused with the GCS-side "Mission Planner" desktop tool — that is out of scope (only QGroundControl is the supported GCS). (source: ADR-010)

Mission profile — 8 h flight, ~150 km² operational sector + ~50 km² transit corridor, ≤400 km² total cached, ~60 km/h cruise, ≤1 km AGL, eastern/southern Ukraine. (source: restrictions.md)

MSP2_SENSOR_GPS — MSP2 message used as the per-frame FC delivery channel for iNav (iNav has no inbound MAVLink external-positioning handler). (source: restrictions.md, AC-4.3)

Nav camera / Navigation camera — The fixed-downward (no gimbal) camera on the UAV; pinned model is adti20. Distinct from the operator-controlled AI camera. (source: restrictions.md §Cameras)

Operator — Pre-flight and post-flight human role: authors the flight route in the Mission Planner UI (suite/ui), classifies the operational area (active-conflict vs stable rear), drives C12 cache provisioning (which reads the Flight from the parent-suite flights REST service, downloads satellite tiles via the Tile Manager for the route bbox, and bakes the takeoff origin into the C10 Manifest), stages calibration onto the companion before takeoff, and after landing triggers the Tile Manager upload run. (source: problem.md, AC-3.4 / AC-6.2, ADR-010, user confirmation 2026-05-09 + 2026-05-11)

Tile Manager — Operator-side component (C11) that owns both directions of network I/O against satellite-provider: pre-flight download (F1) into the local C6 store via the TileDownloader interface, and post-landing upload (F10) from C6 to the parent-suite ingest endpoint via the TileUploader interface (gated on flight state == ON_GROUND). Implemented as a separate binary / image so neither network path is loaded in the airborne companion (ADR-004 process-level isolation). Replaces the earlier "post-landing upload tool" naming after Plan-cycle scope expansion 2026-05-09. (source: user directive 2026-05-09)

satellite-provider — First-class architecture boundary: the suite's existing .NET 8 REST microservice at /Users/obezdienie001/dev/azaion/suite/satellite-provider/. Runs in Docker (:5100, OpenAPI at /swagger); downloads Google Maps tiles; stores them in PostgreSQL + filesystem (./tiles/{zoomLevel}/{x}/{y}.jpg). Read-only from the onboard runtime; receives post-landing tile uploads via a yet-to-be-designed ingest endpoint (parent-suite work, D-PROJ-2). Synonym in older docs: "Suite Sat Service" / "Azaion Suite Satellite Service". (source: parent-suite satellite-provider/README.md, user confirmation 2026-05-09)

Satellite anchored — Source label satellite_anchored: estimate produced by matching the current nav frame against pre-cached satellite tiles. Highest confidence among the three labels. (source: AC-1.4)

Sector classification — Pre-flight operator decision: active-conflict (6-month tile-freshness threshold) vs stable rear (12-month threshold). Drives the freshness gate at ingest and during runtime tile use. (source: AC-8.2, AC-NEW-6, solution.md operator-tooling section)

Source label — Provenance tag carried with every emitted estimate: {satellite_anchored | visual_propagated | dead_reckoned}. (source: AC-1.4)

Suite Sat Service — Synonym for satellite-provider used in earlier docs (problem.md, restrictions.md, solution_draft01/02). The actual implementation in the parent suite is the .NET 8 service; "Suite Sat Service" is the role name. (source: restrictions.md, parent-suite satellite-provider/README.md)

Takeoff origin — LatLonAlt baked into the C10 Manifest by C12 at build time from Flight.waypoints[0]. Consumed at boot by C5 via set_takeoff_origin(origin, sigma_m) (AZ-490) as a Bayesian prior on the initial pose — iSAM2 attaches a PriorFactorPose3; ESKF seeds the nominal position + position-block covariance. Primary cold-start trust anchor per ADR-010; FC EKF GPS is secondary. (source: ADR-010, AZ-490)

Tier-1 / Tier-2 — Testing-environment split: Tier-1 = workstation Docker (fast/cheap); Tier-2 = Jetson hardware (AC-bound). Both appear in the deployment plan and CI matrix per finding F6. (source: _docs/02_document/tests/environment.md)

Tile — Unit of persistent imagery on the companion; basemap-projected, deduplicated; the only persistent imagery format. Mid-flight-generated tiles use the same on-disk format as satellite-provider (./{zoomLevel}/{x}/{y}.jpg + matching metadata schema) so post-landing upload is byte-identical. (source: AC-8.4, AC-8.5, parent-suite satellite-provider/README.md, user confirmation 2026-05-09)

Tile cache — Local on-Jetson store, ≤10 GB, populated pre-flight from satellite-provider, augmented mid-flight by orthorectified nav-camera-derived tiles. (source: restrictions.md, AC-8.3, AC-8.4)

Tile freshness — <6 mo (active-conflict sectors) / <12 mo (stable rear); stale tiles must be rejected or downgraded. (source: AC-8.2, AC-NEW-6)

TTFF / Time To First Fix — From companion boot to first valid emitted external-position frame; budget <30 s p95. (source: AC-NEW-1)

UAV — Fixed-wing unmanned aerial vehicle this system runs on; ~60 km/h cruise, ≤1 km AGL, 8 h flights, eastern/southern Ukraine theater. (source: restrictions.md)

VioStrategy — Pluggable interface (Okvis2 / VinsMono / KltRansac) selected at startup by config; not hot-swappable mid-flight. The interchangeable-strategy pattern (ADR-001) plus build-time exclusion via per-implementation CMake BUILD_* flags (ADR-002) lets the project produce a small deployment binary (links the production-default + the engine-rule-mandatory simple-baseline) and a separate research binary that links every available strategy for the IT-12 comparative-study report. ADR-002 is purely technical (binary size on 8 GB shared Jetson, AC-NEW-1 boot budget, dependency / attack surface, accidental-selection risk); component licenses do not influence which strategy is the deployment-default. (source: solution.md §C1, architecture.md ADR-001 + ADR-002 + ADR-009)

VIO / Visual-Inertial Odometry — Frame-to-frame motion + IMU bias estimation via fused camera + IMU streams (component C1). (source: solution.md §C1)

Visual propagated — Source label visual_propagated: estimate produced by VIO frame-to-frame propagation with no fresh satellite anchor. Mid-confidence. (source: AC-1.4)

VPR / Visual Place Recognition — Descriptor-based retrieval of the nearest satellite tile to the current nav frame (component C2). (source: solution.md §C2)

Waypoint — Ordered (lat, lon, alt, objective, source) entry inside a Flight. Operationally meaningful ordering: waypoints[0] is the planned takeoff point and is extracted by C12 FlightsApiClient as the takeoff origin. C12 envelopes all waypoint lat/lon to derive the cache bbox. DTO shape mirrors suite/flights/Database/Entities/Waypoint.cs. (source: ADR-010, AZ-489)