# Corridor Scan
A *Corridor Scan* is a [mission plan](https://docs.auterion.com/vehicle-operation/auterion-mission-control/useful-resources/mission-planning) for surveying roads, rivers and other path-like ground features. It creates a grid flight pattern that follows a poly-line.
A corridor scan mission must contain at least one *Corridor Scan* pattern. The corridor is a path marked out on the map (shaded in green above). The white line indicates the grid flight path. The green circular markers indicate the points where the vehicle enters and exits the pattern.
The ***Mission editor*** on the right is used to set the corridor: width, altitude, required image resolution, and other properties, and to specify camera settings appropriate for creating geotagged images.
This topic shows how to define a corridor scan mission and the various settings that can be configured in the *Corridor Scan Editor*.
## Create a Corridor Scan Mission
The easiest way to define a corridor scan mission is to use the **Plan view** > **Pattern > Corridor Scan** tool from the *Plan Tools*.
This creates a *template* for a simple end end-to-end structure corridor scan mission for the *current vehicle type*. Often all the user has to do is define the scan area (any items that require configuration are shown with a red border in the mission item list).
{% hint style="info" %}
If a more complex mission is needed, the basic mission can be extended by adding other items before the return item.
{% endhint %}
**To create a corridor scan mission:**
1. Open the ***Plan View,*** select the **Pattern** and then **Corridor scan.**
2. Check that the [Mission Start](https://docs.auterion.com/vehicle-operation/auterion-mission-control/ui-breakdown/mission-editor-tab/mission-item-reference#mission-start-editor-defaults) item settings are correct for the planned scan. In particular, the altitude (**Waypoint altitude**) is high enough to avoid obstacles when travelling to the corridor.
* The green part of the line is the area being scanned while the white line is the proposed flight path.
* Move a filled circle (vertices) at one end of the line to the beginning of the desired path, and the other to the end (drag/drop on the map).
* Select the unfilled circle between the two ends (vertices) to create a new vertix. Move the vertix to the first point in the path where the direction changes.
* Repeat the last step, creating new vertices and moving them onto the desired path.
### **Corridor Scan editor**
The **Mission \_Editor**\_ is used to configure *Camera* and *Grid* settings. The trash/bin icon on the top left can be used to delete the whole item.
1. Select the ***Mission tab*** to edit your Corridor scan pattern.
Set the camera first, before configuring the grid (camera capabilities affects the grid settings).
### Camera Tab
Users can select a *predefined*, *custom*, or *manual* camera. The main difference is that using a predefined or custom camera allows *Mission Control* to calculate an optimal layer height for a trigger distance, and visa versa, while using a manual camera means that these parameters need to be manually calculated (and are therefore harder to change).
The camera settings are ***exactly*** the same as for surveys and structure scans. For more information see: [Survey > Camera](https://docs.auterion.com/vehicle-operation/auterion-mission-control/ui-breakdown/plan/plan-tools/survey#camera-tab).
### Grid Tab
The *Grid* tab is used to set the properties of the scan.
For a *predefined* or *custom* camera the scan settings allow users to choose a desired image overlap and set either desired scan altitude or image resolution for the ground surface (automatically calculating the other value).
| Setting | Description |
| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Overlap** | Overlap between each image capture. This can be configured separately for when flying along grid lines (*Front Lap*) or across them (*Side Lap*). |
| **Altitude** | Survey altitude. The **Ground Res** field is dynamically updated with the resolution required for entered altitude. |
| **Ground Res** | Ground resolution for each image. The **Altitude** field is dynamically updated with minimum value to achieve the entered resolution |
For a *manual* camera, the grid settings are instead specified as shown. Note that if any of these settings need to change, then they may all need to be manually recalculated.
| Setting | Description |
| -------------------- | ----------------------------------------------------------------------- |
| **Altitude** | Altitude to fly the whole path. |
| **Trigger Distance** | Distance over ground between each camera shot. |
| **Spacing** | Distance between adjacent grid (flight path) lines across the corridor. |
#### Corridor Panel
The *Corridor* section is used for grid settings that are independent of the camera. Changes in the settings are reflected in the map.
| Setting | Description |
| ---------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Width** | Set the width of the scan around the polyline that defines the path. |
| **Turnaround dist** | Additional distance added to the outside the survey area for vehicle turn around. |
| **Options** |
Images in turnarounds: Take images when turning/outside of grid.
Relative altitude: Check to specify relative altitude (relative to home location). This is only supported for manual grids that are not using terrain following.
|
| **Rotate entry point** | Button toggles (swaps) the entry and exit points of the scan. |
#### Terrain Panel
*Terrain Following* makes the vehicle maintain a constant height relative to ground throughout the scan (by default, a flying vehicle will follow the corridor path at a fixed altitude).
Terrain following uses terrain heights queried from AirMap servers.
| Setting | Description |
| --------------------------- | ---------------------------------------------------------------------- |
| **Vehicle follows terrain** | Check to enable terrain following (and display the following options). |
| **Tolerance** | The accepted deviation in altitude from the target altitude. |
| **Max Climb Rate** | Maximum climb rate when following terrain. |
| **Max Descent Rate** | Maximum descent rate when following terrain. |
#### Statistics Panel
The Statistics section shows the calculated survey area, photo count, interval, and resolution.
