AERO RANGER FORUM

PILOT SUPPORT

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BY admin
#27
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Structure scan missions are another variant of survey missions. These missions are used for scanning tall vertical structures such as towers, lighthouses, and tall buildings to make 3D models of them. As with other survey type missions, the collected imagery is typically uploaded to a processing service such as Maps Direct for processing into 3D models.

NOTE: If you have a Spark you cannot use this mission. The Spark does not support waypoint missions.

A structure scan mission works in a similar way to linear scan missions, by flying a set of descending horizontal strips around a structure of interest. The main difference is that instead of flying in straight lines, it flies an orbit around the structure, with the structure in the centre. Hence it is suitable for towers and other vertical structures. As with linear scans, the aircraft flies sideways for the bulk of the mission.

You can control the altitude range and the arc of coverage around the structure in this mission type.

Warning: It's important to control the arc of the scan so you are not flying behind the structure. If you lose contact with the drone it may trigger a return to home and potentially crash into the structure. It's your responsibility to maintain line of sight with your drone at all times.

Three steps are required to produce a structure mission:
  1. Setting the mission objectives
  2. Define the point of interest, survey arc and distance from the point of interest
  3. Set the upper and lower altitudes
First, navigate to the Plan screen using the main menu as shown below. Tap the "Hamburger" icon at the top left of the screen to display this menu:

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On the Plan screen, move the map close to the area that you would like to survey and zoom in to a comfortable level. Don't zoom in too far. While you can zoom and scroll later, it is easier to move the map to roughly where you need it first.

When ready to create the mission, press the round blue + button at the bottom right of the screen to reveal the mission selector. Tap on the "Structure scan " item and tap Next to start building a Structure Scan mission.

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Step 1: Mission Objectives

The first step of any mission is the Mission Objectives dialog. This dialog allows you to choose basic settings for the mission and the items on it will adapt to suit the mission type. This will slide in from the right of the screen.

Note that you can exit mission creation by tapping the X at the top left of the objectives dialog. This will cancel new mission creation and retain whatever mission is currently loaded.

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In the example above, there are several important settings that you can change, but in many cases the defaults will be suitable
  • Camera - The camera should show the drone that you are connected to now, or were last connected to.
    • Tap on this section of the dialog to display the camera settings.
    • In structure missions, only JPG photos or video can be taken due to the short time between shots that is required. The camera will default to JPG even if you select RAW.
Tip: You don't have to change Camera settings now, you can change them at any time prior to takeoff. Camera settings are available from the main app menu
  • Min Safe Alt - this is a critical setting for the entire mission.
    • Whatever other settings you choose, no part of the mission can be lower than this altitude.
    • It also defines the altitude at which the vertical part of takeoff finishes and the vertical part of landing begins
    • Make sure the Min Safe Alt is set well above any obstacles such as tall trees or buildings in your area of operations. The safety of the drone and people and property around you is your responsibility.
    • Remember - all altitudes are measured relative to the Home point.
  • Sidelap % - The sidelap % defines the overlap between each of the photos that the aircraft will fly.
    • Given the aircraft is flying sideways for linear scan missions, this has the same effect as the the overlap setting in a survey mission.
    • The higher this value, the more photos will be taken. This can vary from 40% to 95%. 70% is a good default for most work.
  • Overlap % - This affects the vertical distance between the horizontal flight lines, based on the camera properties and distance from the structure you fly. This can vary from 40% to 95%. 70% is a good default for most survey work.
  • Target Speed - this is the speed in m/s that the aircraft will attempt to attain when flying the mission
    • If you set this too fast, you may not have time to react in case of an incident where you need to take manual control.
    • 5m/s=18km/hr=11.2 miles/hr
  • Gimbal Angle - Sets the initial gimbal angle (0=horizontal, 90=straight down).
    • In most cases linear scan missions require an initial 45 degree down angle, but you may change it here.
    • The angle will gradually be reduced (become more horizontal) as the drone flies lower through the mission.
    • You will not have manual gimbal control during flight, so select the correct angle here.
  • Review mission after creation - if you tick this on, the app will remain on the Planning page once you have finished creating the mission, if ticked off, it will automatically return to the Fly page, ready for takeoff.
When you are satisfied with the settings, press NEXT at the top right of the screen

Step 2: Define the mission location and arc

In this step you will define
  • The target or point of interest of the survey. The camera and drone always point at this
  • The arc the aircraft will fly
  • The distance from the target the aircraft will fly
Point of Interest

Tap once on the screen to set the point of interest.

The blue ring and white and black point of interest marker, as shown above, will appear.

You can move the point of interest at any time by dragging it.

Flight arc

The blue ring illustrates the path the aircraft will fly, you can set the arc anywhere from 90 to 360 degrees around the object of interest using the white handles at the end of the arc.

Ensure the arc you set will allow you to maintain line of sight with your drone at all times.

Warning: You must maintain control of, and line of sight with, your aircraft at all times. If  you fly behind the structure, you may lose signal, trigger the return to home and potentially crash into the structure. 

Distance from target

Using the green aircraft icon you can set the distance to fly from the target. Simply drag it closer or further away from the target.

This distance will impact how many photos are taken and the resolution of those photos.

Once you have set the mission location, press the blue OK button.

Tip: To zoom in/out and move or rotate the map, you can use regular pinch/zoom or single finger drag gestures on an area of the map away from the structure scan widget. 

Tip: If you have zoomed in too far, finger gestures may not work correctly. In this case, use the  Image button at the top right of the screen to zoom out one step.

Step 3: Mission Altitude range

The mission altitude range dialog should appear as below

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The final step is to set the altitude for this mission. This work in a similar way to the linear scan mission

Two values are required
  • The estimated structure height
  • The lowest scan height
Tap on the text boxes to pop up the keyboard and enter values.

Est Structure Height (m)

The estimated structure height is your best estimate of the altitude of the top of the structure.
  • This altitude is relative to the Home (takeoff) point, not necessarily the base of the structure (unless you takeoff from there)
  • The software will use this to locate the first level of the flight arc.
  • The actual aircraft altitude in the first level will be above this to ensure it can look down at 45 degrees (or the gimbal angle set in step 1) to cover the top of the structure.
  • Can't be above the legal operating altitude of 122m
Lowest Scan Alt (m)

The lowest scan altitude is where the last level will be located.
  • This must be above the Min Safe Alt (you will not be able to enter a lower number)
  • The number and height of levels in between the upper altitude and lower altitude, will be calculated based on the camera properties and offset distance from the target point.
Once you are satisfied with these settings, press FINISH, the mission waypoints will be created as shown below.

The camera icons indicate where photos will be taken as the aircraft flies around the structure.

This example shows how an arc of less than 360 degrees was used to safely capture most of the target without flying behind it, relative to the home point where the operator is standing.

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Mission Statistics
After the mission is created, basic mission statistics are updated in the white strip beneath the map.

In the above case, the mission is 2.77km long, 30 pictures, 14:26 mins flight time (estimated), 7.8cm per pixel (average, based on distance to the centre of the point of interest)

Final tips for Structure Scan missions:
  • You can fly a Structure Scan mission with the camera set to JPG, RAW or Video.
  • This camera gimbal angle is managed by the drone based on your settings in step 1. You won't have manual control over the gimbal during a Structure Scan mission.
  • The drone does not take terrain into account in any mission type. All altitudes are relative to the takeoff point. Please ensure you set the Min Safe Alt high enough to avoid crashing into terrain, buildings, people or infrastructure at any point of the mission. You are responsible for the safety of your equipment and people and property around you.
To fly this mission, return to the Fly page.
WHAT IS THE HOME POINT?

A critical part of any mission is the Home point.

SUPPORTED DRONE MODELS

Most recent DJI drone models are supported

HOW DO I CHANGE CAMERA SETTINGS?

Camera setting have recently had a major revamp.

How do I zoom the camera

To zoom your camera using AeroRanger

TRY OUT AERORANGER