First steps to become a UgCS pilot
Get familiar with the interface
Seems hard isn't it?
As a matter of fact - it's not.
23 elements cover most of the planning and piloting functions. Planning is the most time consuming but the better it is - the less risky the flight itself, so let's start:
1 MENU button
2 Add new route button
3 Route planning tools
4 Modifying tools
5 Measurement tools
6 No-Fly-Zone drawing tools
7 Compass, cursors coordinates on map and elevation indicator
8 Route’s log
9 Show / hide route’s log button.
10 Vehicle's log
11 Elevation’s profile
12 Vehicle’s command buttons
13 Telemetry’s window
14 Add vehicle button
15 Reserved for further updates.
16 Flight mode/Edit mode
18 License status indicator
19 ADS-B indicator
20 Input mapping
21 Map option menu
22 Location search field
23 Mission’s title field
Planning and first run in emulator or simulator mode
Photogrammetry Mission planning example
Mission planning consists of two stages:
- Initial planning,
- Route optimisation.
First step is to set surveying area using UgCS Photogrammetry tool. Area can be set using visual cues on underlying map or using exact coordinates of edges. The result - survey area is marked with yellow boundaries
Next step is to set GSD and overlapping for camera in Photogrammetry tool's setting window
To take photos, in Photogrammetry tool's setting window define the control action of camera. In example below Set camera by distance triggering action with default values is used.
At this point, initial route planning is completed. UgCS will automatically calculate the flight path of the photogrammetry route
But in most cases the automatically calculated photogrammetry route will not be optimal and in some cases even dangerous to fly (for drone or surrounding). Therefore proceed to optimisation stage.
To optimise the route, it's calculated parameters should be known: altitude, estimated flight time, number of shots, etc.
Part of route's calculated information can be found in Elevation profile window. To access Elevation profile window (if it is not visible on screen) click Parameters icon on the Route card (lower-right corner, see Figure 5) and from the drop-down menu select Show elevation
Elevation profile window will present estimated route length, duration, waypoint count and min/max altitude data:
To get other calculated values, open Route log by clicking on Route status indicator - the green check-mark (upper-right corner, see Figure 7) of the Route card
Using route parameters, it can be optimised to be more efficient and safe.
Survey line direction
By default UgCS will trace survey lines from south to north, but in most cases more optimal will be to fly parallel to the longest boundary line of survey area. To change survey line direction edit Direction angle field in Photogrammetry tool. In the example below, by changing angle to 135 degrees - number of passes is reduced from five to four and route length is 1km instead of 1.3km.
UgCS Photogrammetry tool has the option to define how to trace route according to altitude - with constant altitude above ground (AGL) or above mean sea level (AMSL).
Please refer to your data processing software requirements which altitude tracking method it recommend.
UgCS Team's experience is that the choice of altitude type depends on desired result - for orthophotomap (standard aerial land survey output format) it is better to choose AGL to ensure constant GSD for entire map. If the aim is to produce DEM or 3D reconstruction, use AMSL so the data processing software has more data to correctly determine ground elevation by photos to provide more qualitative output.
In this case UgCS will calculate flight altitude based on lowest point of survey area.
If AGL is selected in Photogrammetry tool's settings, UgCSwill calculate altitude for each waypoint. But in this case terrain following will be rough if no “Additional waypoints” are added
Therefore, if AGL is used, add some “Additional waypoints” flags and UgCS will calculate flight plan with elevation profile accordingly
In general - if flight speed is increased it will minimise flight time. But high speed in combination with large camera exposure can result in blurred images. In most cases 10m/s is the best choice.
Camera control method
UgCS supports 3 camera control methods (actions)
- Make a shot (trigger camera) in waypoint,
- Make shot every N seconds,
- Make shot every N meters.
Not all autopilots support all 3 camera control options. For example (quite old) DJI A2 does support all three options, but newer - starting from Phantom 3 and up to M600, support only triggering in waypoints and by time. DJI promised to implement triggering by distance, but it’s not available yet.
Here are some benefits and drawbacks for all three methods:
Table 1: Benefits and Drawback for camera triggering methods
|In waypoint||Only method that takes shots in planned locations.||Requires a lot of additional waypoints. All autopilots have a maximum limit for waypoints, for example, A2 can handle only 50 waypoints.|
|By time||Doesn't require a lot of additional waypoints||Precision of this method is hard to predict, because it depends on UAV’s actual speed, which depends on wind, temperature, the weight of the payload, acceleration/deceleration, etc.|
|By distance||Doesn't require a lot of additional waypoints and has quite good precision.||Precision depends on selected turn type (see Turn type preference below) distance calculation algorithm of certain autopilot|
- Trigger in waypoints should be preferred when possible
- Trigger by time should be used only if no other method is possible
- Trigger by distance should be used when triggering in waypoints is not possible to use
To select the triggering method in UgCS Photogrammetry tool accordingly, use one of three available icons:
- Set camera mode
- Set camera by the time
- Set camera by the distance
Most autopilots or multirotor drones support different turn types in waypoints. Most popular DJI drones have three turn-types:
It is advisable not to use Bank Turn for photogrammetry missions. Drone interprets Bank Turns as “recommendation destination waypoint” - the drone will fly towards this direction but will almost never pass through the waypoint. Because drone will not pass the waypoint - no action will be executed, meaning - the camera will not be triggered, etc.
Adaptive Bank Turn should be used with caution because the drone can miss waypoints - and again - no camera triggering will be initiated.
Sometimes Adaptive Bank Turn type has to be used to have more short flight time comparing to Stop and Turn. When using Adaptive Bank Turns it is recommended to use Overshoot (see next chapter) for the photogrammetry area.
Drones, e.g., DJI Phantom 3, Phantom 4, Inspire, M100 or M600, with integrated gimbal have the option to control camera position as part of an automatic route plan.
It is advisable to set the camera to nadir position in the first waypoint and in a horizontal position before landing to prevent lenses from potential damage.
To set camera position, select waypoint preceding the Photogrammetry area and click Set camera attitude/zoom and enter "90" in the "Tilt" field.
As described previously, this waypoint should be a Stop&Turn type, otherwise, the drone could skip this action.
To set camera to horizontal position - select last waypoint of survey route and click Set camera attitude/zoom and enter "0" in the "Tilt" field.
Initially, overshoot was implemented for fixed-wing (airplane) drones to have enough space manoeuvring a U-turn.
Overshoot can be set in photogrammetry tool to add an extra segment to both ends of each survey line.
In the example above,UgCS added 40m additional segments to both ends of each survey line.
Adding overshoot is useful for copter-UAVs in two situations:
Example of a blurred image taken by a drone in a rotation to next waypoint
It is important to check the take-off area at the site before flying any mission! To better explain the best practice how to set a Take-off point - first discuss an example how it should not be done. Supposing that the take-off point in example mission would be from the point marked with airplane-icon and drone pilot would upload route on the ground with a set Automatic mission for automatic take-off.
Most drones in automatic take-off mode would climb to low altitude about 3-10meters and then fly straight towards the first waypoint. Other drones would fly towards the first waypoint straight from the ground. Looking closely at the example map (Figure 17), some trees between take-off point and the first waypoint can be noticed. In this example, the drone more likely will not reach safe altitude and will hit the trees.
Not only surrounding can affect Take-off planning. Also the fact, that drone manufacturers can change drones elevation behaviour in drone firmware, therefore after firmware updates, it is recommended to check drones automatic take-off mode.
Also a very important consideration - most small UAVs use relative altitude for mission planing. Altitude counted relatively according to the first waypoint is a second reason why actual take-off point should be near the first waypoint and on the same terrain level.
UgCS Team recommends to place the first waypoint as close as possible to actual take-off point and specify safe take-off altitude (≈30m in most situations will be above any trees, see below). This is the only method that warrants safe take-off for any mission. It also protects from any weird drone behavior, unpredictable firmware updates, etc.
Entry point to the survey grid
In the previous example, it can be noticed, that after adding the take-off point, route's survey grid entry point was changed - because, if an additional waypoint is added next to the Photogrammetry area, UgCS will plan to fly the survey grid starting from nearest corner to the previous waypoint.
To change the entry point to the survey grid, using the Modifier tool insert an additional waypoint close to the desired starting corner.
If no landing point will be added outside photogrammetry area after survey mission, the drone will fly and hover in the last waypoint. There are two options for landing:
In situations when radio link with the drone is lost, for example, if the survey area is large or there are problems with Remote Controller. Depending on the drone and it’s settings one of these actions can occur:
- Drone will return to the home location automatically if lost radio link to the ground station,
- Drone will fly to the last waypoint of the survey area and hover as long as battery capacity will enable that, then:
- the drone will perform an emergency landing,
- or it will try to fly to the home location.
A recommendation is to add explicit landing point to route, to avoid relying on unpredictable drone behaviour or settings.
If drone doesn’t support automatic landing or pilot prefers to land manually, place route’s last waypoint over planned landing point with altitude not only for comfortable manual drone descending and landing, but also above obstacles in surrounding area. In general, 30m is the best choice.
Photogrammetry tool has a magic parameter “Action Execution” with three possible values:
- Every point
- At the start
- Forward passes
This parameter defines how and where camera actions specified for Photogrammetry tool will be executed.
Most useful option for photogrammetry/survey missions is to set Forward passes - drone will make photos only on survey lines, but will not make excess photos on perpendicular lines.
Complex survey areas
UgCS enables photogrammetry/survey mission planning also for irregular areas, having the functionality to combine any number of photogrammetry area in one route, avoiding splitting the area into separate routes.
For example, if a mission has to be planned for two fields connected in a shape of “T” and if these two fields are marked as one Photogrammetry area - the whole route will not be optimal regardless any direction of survey lines.
If the survey area is marked as two photogrammetry areas within one route - survey lines for each area can be optimised individually
Deploy ground control points
Ground control points are mandatory if the survey's output map has to be precisely aligned to coordinates on Earth.
There are a lot of discussions about the necessity of ground control points in cases when a drone is equipped with Real Time Kinematics (RTK) GPS receiver with centimetre-level accuracy.
It is useful that RTK GPS enables to define coordinates of drone location with centimetre-level accuracy. But the drone coordinates are not enough, as for precise map aligning image centre coordinates are necessary to be provided.
Data processing software like Agisoft Photoscan, DroneDeplay, Pix4d, Icarus OneButton and others will produce very accurate maps using geotagged images, but the real precision of the map will not be known without ground control points.
Conclusion: ground control points have to be used to create Survey-Grade result. For a map with approximate precision, it is sufficient to rely just on RTK GPS and capabilities of data processing software.
Fly your mission
For a carefully planned mission, flying it is the most straightforward step. Mission execution differs according to the type of UAV and equipment used, therefore it will not be described in detail in this topic (please refer to equipment’s and UgCS
Important issues before flying
- In most countries, there are strict regulations for UAV usage. Always comply with the regulations! Usually, these rules can be found on the website of local aviation authority.
- In some countries, special permission for any kind of aerial photo/video shooting is needed. Please check local regulations.
- In most cases missions are planned before arriving at the flying location (e.g., in office, at home) using satellite imaginary from Google maps, Bing, etc. Before flying always check actual circumstances at the location. There could be a need to adjust take-off/landing points, for example, to avoid tall obstacles (e.g., trees, masts, power lines) in your survey area.
Image geotagging is optional if ground control points were used, but almost any data processing software will require less time to process geotagged images.
Some latest and professional drones with an integrated camera can geotag images automatically during flight, in other cases, images can be geotagged in UgCS after a flight.
Very important: UgCS uses telemetry log from the drone, that is received via a radio channel, to extract drone’s attitude for certain moment (when pictures were taken). To geotag pictures using UgCS assure robust telemetry reception during flight.
Starting UgCS PRO version 2.12 UgCS MAPPER is launched - a desktop geo-referenced image processing software, to create 2D maps in-field, requiring no internet connection. In-field assembled map provides certainty for UAV surveyors that acquired images quality and density is sufficient. This information is crucial to decide whether the flight should be repeated before leaving the surveying area.
To make a more detailed analysis and 3D models from acquired images, third-party software can be used. UgCS Team experience is that Agisoft Photoscan is a very powerful and flexible software, but some users may find that for getting the desired result too much input effort is needed. Most uncomplicated solution for users is the online service DroneDeploy. All other software packages and services will fit somewhere between these two in terms of complexity and output quality.
Import created map to UgCS
Should the need arise for the mission to be repeated in the future, " UgCS enables to import GeoTiff file as map layer and use it for mission planning. More detailed instruction can be found in UgCS User Manuals. See the result of an imported map created using UgCS photogrammetry tool imported as GeoTiff file.
Imported GeoTiff map as a layer. The map is the output of a Photogrammetry survey mission panned with UgCS
DJI simulator with UgCS
- Turn on the laptop with an installed UgCS desktop
- Turn on the Android mobile device with installed UgCS for DJI on it
- Create a WiFi access point on the Android mobile device
- Connect your laptop to the created WiFi access point
- Run UgCS
- Remove propellers of the drone
- Turn on the drone
- Turn on the drone’s Remote Controller (RC)
- Connect the RC with the Android mobile device
- If the UgCS for DJI doesn’t start automatically, launch it
- When the connection with the drone has been established, check that the UCS indicator of UgCS for DJI is green and that UgCS desktop is displaying telemetry of the drone
- In UgCS for DJI choose MENU and check the Simulator’s checkbox
- A warning to remove drone’s propellers will be displayed, click OK
- Now GPS data will be transferred (by default the drone will be placed at the Spilve airport in Riga, Latvia)
- Check that the drone is in DISARM status and upload the route to the drone. Upon successful upload, the drone will be placed on the first waypoint / Home location of your mission
- To start the simulation of the flight, start motors by pulling both throttles (control sticks) to the inner-bottom corners – UgCS telemetry will display “Arm”. (The drone engines should not start, but for safety reasons, it is recommended to remove propellers.)
- IMPORTANT!!! Raise the drone a few meters up (left stick up, RC should be in MODE 2).
- Click “Auto Mode” and accept the command in either UgCS or UgCS for DJI – the drone should start the mission.
In the simulation mode, it is possible to follow the flight of the drone in UgCS and control whether pictures are taken according to the route’s settings (if turn type “Stop & Turn” is in use).