# Glossary

**Status**: confirmed-by-user  
**Date**: 2026-05-01

## Aerial VPR

Visual place recognition over aerial/nadir imagery; used to retrieve candidate satellite/cache chunks for a UAV frame. (source: `solution.md`)

## ADTi 20MP 20L V1

Selected navigation-camera family. Public product pages list Sony APS-C CMOS, 5456 x 3632 max image size, 23.20 x 15.40 mm sensor, 4.25 um pixel pitch, Sony E mount, and 2 fps continuous capture; final manufacturer specification remains a verification risk. (source: `restrictions.md`, user-confirmed open-question review)

## Anchor

Accepted absolute visual match to a georeferenced cache tile, used to correct VO/IMU drift. (source: `acceptance_criteria.md`, `solution.md`)

## ArduPilot Plane SITL

Simulation environment used to verify `GPS_INPUT`, spoofing, failsafe, and MAVLink behavior with the production Plane parameter set. (source: `acceptance_criteria.md`, `tests/environment.md`)

## BASALT VIO

Selected production relative visual-inertial odometry candidate. It consumes calibrated navigation-camera frames and IMU data but does not own the product's safety, anchor, cache, or MAVLink semantics. (source: `solution.md`)

## Cache Poisoning

Failure mode where a misaligned onboard-generated tile is written back and later corrupts future satellite-cache anchors. (source: `acceptance_criteria.md`)

## COG Tile

Cloud Optimized GeoTIFF raster object used as the write-new unit for georeferenced service tiles and generated onboard tiles. (source: `solution.md`)

## FDR

Flight Data Recorder. Bounded per-flight recorder for estimates, IMU traces, emitted MAVLink, health telemetry, tile writes, and audit evidence; raw nav/AI frames are not retained. (source: `acceptance_criteria.md`, `solution.md`)

## Generated Tile

In-flight orthorectified tile created from navigation-camera imagery and stored locally for post-flight Satellite Service sync. (source: `acceptance_criteria.md`)

## `GPS_INPUT`

MAVLink message used as the ArduPilot GPS substitute in v1. It carries WGS84 coordinates, fix type, accuracy fields, and ignore flags. (source: `acceptance_criteria.md`, `solution.md`)

## Kimera Backup

BSD-friendly VIO backup candidate if BASALT fails project replay/runtime gates. (source: `solution.md`)

## Mahalanobis Gate

Statistical consistency gate used to reject anchor updates that are inconsistent with the current estimator state and covariance. (source: `solution.md`)

## Nadir Camera

Fixed downward-pointing navigation camera used for localization. It is not gimbal-stabilized. (source: `restrictions.md`)

## OpenVINS Reference

GPLv3 VIO/covariance baseline used for replay comparison and uncertainty calibration; not the default production dependency. (source: `solution.md`)

## Public Replay Dataset

External dataset used to cover validation gaps in the current sample data, especially synchronized nadir camera, IMU, GNSS/ground truth, and reference imagery. MUN-FRL and ALTO are first-choice candidates. (source: `tests/test-data.md`)

## QGroundControl

Supported ground station that receives downsampled status and failsafe messages at 1-2 Hz. (source: `restrictions.md`, `acceptance_criteria.md`)

## Representative Replay Rig

Final acceptance dataset or hardware setup from the target flight profile with synchronized nav camera, FC IMU/attitude/airspeed/altitude, emitted MAVLink, and ground truth. (source: `acceptance_criteria.md`, `tests/test-data.md`)

## Safety/Anchor Wrapper

Project-owned layer around BASALT that calibrates confidence, fuses satellite anchors, owns source labels, handles degraded modes, gates generated tiles, and emits MAVLink outputs. (source: `solution.md`)

## Satellite Service

External Azaion Suite component that prepares the offline satellite cache before flight and ingests generated tiles after landing. The onboard system does not call it in-flight. (source: `restrictions.md`)

## Source Label

Categorical label attached to every estimate: `{satellite_anchored, vo_extrapolated, dead_reckoned}`. (source: `acceptance_criteria.md`)

## Tile Freshness

Runtime age gate for cache tiles: active-conflict sectors require newer imagery than stable rear sectors. (source: `acceptance_criteria.md`)

## Visual Blackout

State where the navigation camera provides no usable localization signal because of clouds, occlusion, whiteout, or similar visual loss. (source: `acceptance_criteria.md`)

## VPR Chunk

Ground-footprint-sized retrieval unit, approximately 600-800 m with overlap, decoupled from the storage tile convention. (source: `acceptance_criteria.md`)