> ## Documentation Index
> Fetch the complete documentation index at: https://docs.altnautica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting Started

> Pick a mode, wire the hardware, install the plugin, and arm. A short walkthrough that links the rest of the Vision Navigation documentation.

# Getting Started with Vision Navigation

If this is your first time flying GPS-denied with an ADOS drone, this
page walks the shortest path from a fresh drone to a hovering one. You
will pick a mode, wire the hardware, install the plugin, and arm.

The full reference docs live one click away under each section. Skip
ahead if you already know what you want.

## 1. Pick a mode

The plugin runs one of six estimator modes. The right mode depends on
what hardware you have and where you plan to fly.

<Steps>
  <Step title="Have a downward camera AND a rangefinder?">
    Use `optical_flow`. The default GPS-denied path. Low-altitude
    hover and waypoint flight, indoors and out.
  </Step>

  <Step title="Have a downward camera but NO rangefinder?">
    Use `optical_flow_degraded`. Same tracker, scale comes from a
    baro or GPS fallback. Reduced accuracy; the GCS labels the
    estimator as degraded.
  </Step>

  <Step title="Have a forward camera plus an NPU board?">
    Use `vio_openvins` or `vio_vins_fusion`. Full 6-DOF pose. Works
    at altitude and in scenes the downward camera cannot track.
  </Step>

  <Step title="Have two cameras and CPU headroom?">
    Use `hybrid_of_plus_vio`. Both estimators feed the EKF in
    parallel. The most resilient option, at the cost of compute.
  </Step>
</Steps>

See the [full Modes page](/drone-agent/vision-nav-modes) for the
per-mode hardware matrix and pre-arm checks.

## 2. Wire the hardware

The bare minimum:

* A companion computer running the ADOS Drone Agent (Pi 4B, Pi 5,
  Radxa ROCK 5C Lite, or any other [supported board](/drone-agent/vision-nav-hardware)).
* A camera mounted in the direction the chosen mode needs. Optical
  flow is always downward. VIO accepts either forward (indoor /
  corridor) or downward (over-ground: agriculture, survey, SAR,
  pipeline patrol). Hybrid uses both. The wizard surfaces an
  explicit orientation picker under VIO and hybrid.
* A rangefinder when the chosen mode requires one (`optical_flow` and
  `hybrid_of_plus_vio` need one; the other modes do not).
* A flight controller running ArduPilot 4.5 or newer, PX4 1.14 or
  newer, or iNav 7.0 or newer. The plugin auto-detects which.
  Betaflight is not supported; it has no position estimator to consume
  flow or VIO samples.

The [Hardware page](/drone-agent/vision-nav-hardware) lists tested
camera and rangefinder combinations.

## 3. Install the plugin

From Mission Control, open the drone's detail panel, switch to the
Plugins tab, and click Install. Pick the `vision-nav.adosplug`
archive. Walk the six-stage dialog; grant the permissions; enable the
plugin.

Full walkthrough: [Install on a drone](/drone-agent/vision-nav-install).

## 4. Calibrate (VIO modes only)

If you picked a VIO mode the plugin needs camera intrinsics, a
camera-IMU extrinsics file, and a static time offset between the
two clocks. The GCS sensors card has a Calibrate CTA that opens a
seven-step guided wizard:

1. Print the bundled AprilGrid PDF at the documented scale.
2. Open the Vision Nav tab and tap Calibrate.
3. Walk the wizard. Captures 20 to 30 frames at varied poses, a
   roughly 30-second IMU motion segment, then submits to the agent.
   Takes 3 to 5 minutes the first time.
4. The verify step shows the new intrinsics next to any previously
   loaded ones. Apply persists the result; the live estimator picks
   it up on the next tick.

OF modes can skip this step. Default intrinsics are good enough for
the OF tracker.

Operators with an existing Kalibr `camchain.yaml` can upload it
directly without running the wizard; the
[Calibration page](/drone-agent/vision-nav-calibration) documents
the upload path.

Full walkthrough: [Calibration](/drone-agent/vision-nav-calibration).
Technical reference: [Calibration math](/drone-agent/vision-nav-calibration-math).

## 5. Pre-arm and fly

Open the Vision Nav tab on the drone detail panel. The pre-arm card
shows a check row per mode-relevant input. Green means the row is
ready; yellow means it is initializing; red means it is blocking.

When every row is green:

1. Confirm the flight controller's source-set parameters match the
   selected mode. For ArduPilot this is `EK3_SRC1_VELXY`,
   `EK3_SRC1_POSXY`, `EK3_SRC1_YAW` (the GCS source-set switcher
   handles the runtime flip). For PX4 it is `EKF2_OF_CTRL` or
   `EKF2_EV_CTRL` depending on mode (PX4 needs a parameter write +
   EKF restart; runtime switching is not supported).
2. Arm. The drone takes off into the EKF state the plugin feeds.

If anything goes wrong mid-flight, the
[Troubleshooting page](/drone-agent/vision-nav-troubleshooting) has
decision trees for the four common failure families.

## 6. What's next

* [Modes](/drone-agent/vision-nav-modes) for a deeper read on the six
  estimators and the pre-arm matrix.
* [How it works](/drone-agent/vision-nav-how-it-works) for a
  system-level walkthrough of the camera-to-EKF chain.
* [Fallback methods](/drone-agent/vision-nav-fallback-methods) for
  what happens when a sensor degrades or a mode fails.
* [Features](/drone-agent/vision-nav-features) for the use cases each
  mode unlocks.
* [Mode comparison](/drone-agent/vision-nav-mode-comparison) for a
  side-by-side decision table.
* [FAQ](/drone-agent/vision-nav-faq) for the questions that come up
  every time.