Structure Scan

A Structure Scan mission is used for the visual inspection of buildings or creating 3-dimensional models of structures. It defines a layered grid flight pattern that captures images over vertical surfaces (e.g. walls) around a structure with an arbitrary polygonal (or circular) ground footprint.

The image above shows a structure scan. The green inner-polygon marks out the ground footprint of the structure, while the white line around it indicates the vehicle flight path. The green numbered circle on the flight path is the scan entry/exit point (where the scan starts).

The scan divides the structure evenly into layers; the vehicle flies all the way around the structure at a particular altitude and scan distance, then repeats the process at each layer until the whole surface has been scanned.

Users can set the scan bottom altitude to avoid obstacles at the bottom of the structure, and the entrance/exit altitude to avoid obstacles as the vehicle travels to/from the scan.

This topic shows how to create a structure scan mission and the various settings that can be configured in the Structure Scan Editor.

Create a Structure Scan Mission

The easiest way to define a structure scan mission is to use the Plan view > Pattern** > Structure Scan** tool.

This creates a template for a simple end end-to-end structure 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).

If a more complex mission is needed, the basic mission can be extended by adding other items before the return item.

To create a structure scan mission:

1. Open the Plan View and select the Pattern > Structure scan button. This creates a basic structure scan mission appropriate for the current vehicle type (clearing any existing mission).\

   
2. Check that the Mission Start item settings are correct for the planned scan. In particular that the altitude (Waypoint altitude) is high enough to avoid obstacles when travelling to the structure.

   
3. From the Mission editor, select the Mission to edit the Structure scan settings.\

   
4. Choose your survey area:

• Basic: Create a polygon footprint starting from a rectangle. The filled circles (vertices) and center can be moved where needed (using the map). New vertices can be created by selecting the markers between existing vertices, and then moved.Move and create vertices as needed so that the green area overlays the edges of the structure to be scanned.

• Circular: Create a circular footprint. The filled circles in the center and on the circumference can be moved on the map to change the circle's position and size. Center the scan on a circular structure and then adjust the radius until the green area overlays the edges of the structure.

• Trace: Trace around the shape of the target scan footprint. The filled circles can be moved on the map while tracing (you cannot move the center point or create new vertices). Select the Done Tracing button to stop tracing and display the Polygon Tools.

Select the Done with Tracing button when the scan footprint is defined. This will allow other properties of the survey to be edited in the Structure Scan Editor.

Note that the Structure Scan editor has a red border. This indicates that the item is undefined and must be explicitly set before saving the mission.

Structure Scan Editor (Settings)

The mission Structure Scan Editor is used to configure Camera and Grid settings. The trash/bin icon can be used to delete the whole item

Set the camera first, before configuring the grid (camera capabilities affects the grid settings).

Camera Tab

Users can select a predefined camera, custom camera, or "manual camera". The main difference is that using a predefined camera allows Auterion 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 for Corridor Scans). For more information see: Survey > Camera.

Structure Scan Camera Settings: Custom Camera

Grid Tab

The Grid tab is used to set the properties of the scan.

The screenshot below shows the properties when using a predefined or custom camera.

Structure Scan Grid Settings: Predefined/Custom Camera

The scan settings allow users to choose a desired image overlap and set either desired scan distance or image resolution for the structure surface (automatically calculating the other value).

Setting	Description
Overlap	Overlap between each image capture. Front Lap is image overlap from top to bottom (increasing shrinks layer height and increases layer count). Side Lap is image overlap at sides (increasing takes more images in each lap/layer scan)
Scan Distance	Distance of vehicle from structure during scan (affects Ground Res).
Ground Res	Ground resolution for each image (affects Scan Distance).

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
Scan Distance	Distance from vehicle to structure during scan.
Layer Height	The height of each layer.
Trigger Distance	Horizontal distance over ground between each camera shot. Note that the camera is only triggered while flying the layer path. It does not trigger images while transitioning from one layer to the next.

Scan Panel

The Scan section configures the order in which layers are captured, gimbal pitch, and other settings that ensure a clear flight path before, during, and after the scan.

Setting	Description
Start Scan From Top/Bottom	The direction in which layers are scanned (top to bottom, or bottom to top).
Structure Height	The height of the object being scanned.
Scan Bottom Alt	This setting is used to avoid obstacles around the base of the structure. It adjusts the bottom of the structure to be above the ground, and hence the altitude of the first scan (the height of the lowest layer flight path is shown in the scan statistics as Bottom Layer Alt).
Entrance/Exit Alt	The vehicle will fly from the last waypoint to the Entrance/Exit point at this altitude and then descend to the initial layer to start the scan. The vehicle will ascend to this altitude after completing the scan and then move to the next waypoint. The setting is used to avoid obstacles between the structure to be scanned and the preceding/following waypoints.
Gimbal Pitch	Gimbal pitch for the scan.
Rotate entry point	Toggle the start/finish point to the next vertix/position on the flight path.

Statistics Panel

The Statistics panel summarizes the calculated scan information: number of layers, layer height, top and bottom layer altitudes, photo count, photo interval, and resolution.