Few Improvements To QGC User Guide (#298)

en/FlyView/FlyView.md

@@ -21,7 +21,7 @@ The screenshot above shows the main elements of the fly view:
 - **Fly Toolbar:** Key status information for sensors (GPS, battery, RC control), and vehicle state (Flight mode, Armed/Disarmed status).
   - Select the sensor indicators to view more detail.
   - Press the *Flight mode* text (e.g. "Hold") to select a new mode. Not every mode may be available.
-  - Press the *Armed/Disarmed* text to toggle the armed state. If flying you can press this text to *Emergency Stop*.
+  - Press the *Armed/Disarmed* text to toggle the armed state. While flying you can press this text for *Emergency Stop*.
 - **Fly tools:** You can use these to:
   - Toggle between takeoff/land.
   - Pause/restart the current operation (e.g. landing, or the mission).
@@ -33,7 +33,7 @@ The screenshot above shows the main elements of the fly view:
 - **[Video/Switcher](#video_switcher):** Toggle between video or map in a window.
   - Press the element to switch *Video* and *Map* to foreground.
   - *QGroundControl* supports RTP and RTSP video streaming over your vehicles UDP connection. 
-    It also support directly connected UVC device support.
+    It also supports directly connected UVC devices.
     QGC video support is further discussed in the [Video README](https://github.com/mavlink/qgroundcontrol/blob/master/src/VideoStreaming/README.md).
   - A [Telemetry Overlay](../FlyView/VideoOverlay.md) is automatically generated as a subtitle file
 - **Confirmation Slider:** Context sensitive slider to confirm requested actions. 
@@ -47,7 +47,7 @@ For example, the multi-vehicle selector is only displayed if you have multiple v
 
 The instrument panel is a multi-page widget that displays information about the current vehicle, including: telemetry, camera, video, system health, and vibration information.
 
-The default page displays vehicle telemetry - use the drop down menu on the to right to select the other options.
+The default page displays vehicle telemetry - use the drop down menu on the top right to select the other options.
 
 ### Values (Telemetry)
 
@@ -92,7 +92,7 @@ When enabled, you can start/stop the video stream, enable a grid overlay, change
 ### Health
 
 The health page shows you the health of the systems within your vehicle.
-*QGroundControl* will switch to this page automatically if any systems change to unhealthy.
+*QGroundControl* will switch to this page automatically if any system changes to unhealthy.
 
 ![Instrument Page - Vehicle Health Good](../../assets/fly/instrument_page_health_good.jpg)
 ![Instrument Page - Vehicle Health Bad](../../assets/fly/instrument_page_health_bad.jpg)
@@ -115,13 +115,13 @@ The following sections describe how to perform common operations/tasks in the Fl
 
 An automated preflight checklist can be used to run through standard checks that the vehicle is configured correctly and it is safe to fly.
 
-To you the checklist, first enable the tool by navigating to [Application Settings > General > Fly View](../SettingsView/General.md) and selecting the **Use preflight checklist** checkbox.
+To view the checklist, first enable the tool by navigating to [Application Settings > General > Fly View](../SettingsView/General.md) and selecting the **Use preflight checklist** checkbox.
 The tool will then be added to the *Flight Tools*. 
 Press it to open the checklist:
 
 ![Pre Flight Checklist](../../assets/fly/pre_flight_checklist.jpg)
 
-Once you have performed each test, select it on it in the UI to mark it as complete.
+Once you have performed each test, select it on the UI to mark it as complete.
 
 ### Arm {#arm}
 
@@ -148,7 +148,7 @@ To disarm the vehicle select **Armed** in the *Fly Toolbar* when the vehicle is
 
 ### Emergency Stop {#emergency_stop}
 
-Emergency stop is effectively the same as disarming the vehicle while you are flying.
+Emergency stop is effectively the same as disarming the vehicle while it is flying.
 Your vehicle will crash!
 
 To disarm the vehicle select **Armed** in the *Fly Toolbar* when the vehicle is flying.
@@ -157,7 +157,7 @@ To disarm the vehicle select **Armed** in the *Fly Toolbar* when the vehicle is
 
 ### Takeoff {#takeoff}
 
-> **Tip** If you are starting a mission for a multicopter *QGroundControl* will automatically perform the takeoff step.
+> **Tip** If you are starting a mission for a multicopter, *QGroundControl* will automatically perform the takeoff step.
 
 To takeoff (when landed):
 1. Press the **Takeoff** button in the *Fly Tools* (this will toggle to a **Land** button after taking off).
@@ -178,14 +178,15 @@ You can land at the current position at any time while flying:
 
 ### RTL/Return
 
-Return to the home position at any time while flying:
+Return to a "safe point" at any time while flying:
 1. Press the **RTL** button in the *Fly Tools*.
 1. Confirm RTL using the slider.
 
-![land](../../assets/fly/land.jpg)
-
-> **Note** The vehicle may also land at the home position, depending on its type and configuration.
+![rtl](../../assets/fly/rtl.jpg)
 
+> **Note**  Vehicles commonly return to the "home" (takeoff) location and land.
+> This behaviour depends on the vehicle type and configuration. 
+> For example, rally points or mission landings may be used as alternative return targets.
 
 ### Change Altitude {#change_altitude}
 
@@ -204,7 +205,7 @@ You can change altitude while flying, except when in a mission:
 
 After taking off you can specify that you want to fly to a particular location.
 
-1. Press the map where you want the vehicle to move and select **Go to location** on the popup.
+1. Left click/Press on the map where you want the vehicle to move and select **Go to location** on the popup.
 
   ![Goto or orbit](../../assets/fly/goto_or_orbit.jpg)
 
@@ -222,7 +223,7 @@ After taking off you can specify that you want to fly to a particular location.
 
 After taking off you can specify that you want to orbit a particular location.
 
-1. Press on the map (near the centre of your desired orbit) and select **Orbit at location** on the popup.
+1. Left click/Press on the map (near the centre of your desired orbit) and select **Orbit at location** on the popup.
 
   ![Goto or orbit](../../assets/fly/goto_or_orbit.jpg)
 
@@ -237,7 +238,7 @@ After taking off you can specify that you want to orbit a particular location.
 
 ### Pause
 
-You can pause most operations, including taking off, landing, RTL, missions, Orbit at location. 
+You can pause most operations, including taking off, landing, RTL, mission execution, orbit at location. 
 The vehicle behaviour when paused depends on the vehicle type; typically a multicopter will hover, and a fixed wing vehicle will circle.
 
 > **Note** You cannot pause a *Goto location* operation.
@@ -273,7 +274,7 @@ You can *continue* mission from the *next* waypoint when you're flying (the *Con
 
 > **Note** Continue and [Resume mission](#resume_mission) are different!
   Continue is used to restart a mission that has been paused, or where you have taken off, so you've already missed a takeoff mission command.
-  Resume mission is used when you've used a RTL or landed midway through a mission (e.g. for a battery change) and then wish to continue the next mission item (i.e. it takes you to where you were up to in the mission, rather than continuing from you place in the mission).
+  Resume mission is used when you've used a RTL or landed midway through a mission (e.g. for a battery change) and then wish to continue the next mission item (i.e. it takes you to where you were up to in the mission, rather than continuing from your place in the mission).
 
 You can continue the current mission while (unless already in a mission!):
 1. Press the **Action** button on the *Fly Tools*
@@ -317,7 +318,7 @@ This is meant to prevent issues where stale missions are unknowingly left on a v
 ### Display Video {#video_switcher}
 
 When video streaming is enabled, *QGroundControl* will display the video stream for the currently selected vehicle in the "video switcher window" at the bottom left of the map.
-You can press the switcher anywhere to toggle *Video* and *Map* to foreground (below we show the video in the foreground).
+You can press the switcher anywhere to toggle *Video* and *Map* to foreground (in the image below, the video is shown in the foreground).
 
 ![Video Stream Record](../../assets/fly/video_record.jpg)
 
@@ -326,7 +327,7 @@ You can press the switcher anywhere to toggle *Video* and *Map* to foreground (b
 You can further configure video display using controls on the switcher:
 
   ![Video Pop](../../assets/fly/video_pop.jpg)
-- Resize the switcher by dragging the icon in the to right corner.
+- Resize the switcher by dragging the icon in the top right corner.
 - Hide the switcher by pressing the toggle icon in the lower left.
 - Detach the video switcher window by pressing on the icon in its top left corner
   (once detached, you can move and resize the window just like any other in your OS).

en/FlyView/VideoOverlay.md

@@ -1,6 +1,6 @@
 # Video Overlay
 
-When QGroundControl is recording a video stream to file, it will also export a subtitle file with telemetry data that can be used to overlay the telemetry on the video during playback. Whichever telemetry values are selected for display in the telemetry [values widget](FlyView.md#values-telemetry) will also be exported to the overlay. The overlay values are updated at 1Hz.
+When QGroundControl is recording a video stream to a file, it will also export a subtitle file with telemetry data that can be used to overlay the telemetry on the video during playback. Whichever telemetry values are selected for display in the telemetry [values widget](FlyView.md#values-telemetry) will also be exported to the overlay. The overlay values are updated at 1Hz.
 
 ![Values Widget](../../assets/fly/overlay_widget.png)
 

en/FlyView/replay_flight_data.md

@@ -3,7 +3,7 @@
 > **Warning** This feature is intended primarily for **autopilot developers**/**vehicle creators**.
   It is only supported on desktop builds (Windows, Linux, Mac OS).
 
-The *Replay Flight Data* features allows users to replay a telemetry log, enabling review of past or problematic flights.
+The *Replay Flight Data* feature allows users to replay a telemetry log, enabling review of past or problematic flights.
 The flight can be started, paused, stopped, restarted etc.
 
 > **Note** *QGroundControl* treats flight replay like an active connection. 
@@ -21,8 +21,8 @@ To replay a flight:
 1. When a log is loaded you can use the:
    - **Pause/Play** button to pause and restart playing.
    - *Slider* to drag to a new position in the log.
-   - *Rate* selector to choose how quickly the log is run.
-1. To stop relay (i.e. to load a new file to replay), first pause the flight, and then select **Disconnect** (when it appears).
-   After disconnecting the **Load Telemetry Log** button will be displayed.
+   - *Rate* selector to choose the playback speed.
+1. To stop replay (i.e. to load a new file to replay), first pause the flight, and then select **Disconnect** (when it appears).
+   After disconnecting, the **Load Telemetry Log** button will be displayed.
 
 > **Tip** You can inspect the running replay in more detail using the [MAVLink Inspector](../analyze_view/mavlink_inspector.md).

en/PlanView/Pattern.md

@@ -8,6 +8,6 @@ The available pattern tools depend on the vehicle (and support for the vehicle-t
 Pattern | Description | Vehicles
 --- | --- | ---
 [Survey](../PlanView/pattern_survey.md) | Create a grid flight pattern over a polygonal area. <br />You can specify the polygon as well as the specifications for the grid and camera settings appropriate for creating geotagged images. | All 
-[Structure Scan](../PlanView/pattern_structure_scan_v2.md) | Create a grid flight pattern that captures images over vertical surfaces (polygonal or circular). <br />These are typically used for the visual inspection or creation of 3d models of structures. | MultiCopter, VTOL
+[Structure Scan](../PlanView/pattern_structure_scan_v2.md) | Create a grid flight pattern that captures images over vertical surfaces (polygonal or circular). <br />These are typically used for the visual inspection or creation of 3D models of structures. | MultiCopter, VTOL
 [Corridor Scan](../PlanView/pattern_corridor_scan.md) | Create a flight pattern which follows a poly-line (for example, to survey a road). | All
 [Fixed Wing Landing](../PlanView/pattern_fixed_wing_landing.md) | Add a landing pattern for fixed wing vehicles to a mission. | Fixed Wing

en/PlanView/PatternPresets.md

@@ -29,4 +29,4 @@ If you want to view what the exact settings are for a Preset switch back to **Cu
 
 ## Presets In A Plan File
 
-The currently selected Preset is also saved in the Plan file such that when you load the Plan back the preset will once again be selected. Keep in mind that presets are specific to your version of QGroundControl. If you share a Plan file with a preset with another user incorrect behavior may occur if that other user also have a preset of the same name but different settings.
+The currently selected Preset is also saved in the Plan file such that when you load the Plan back the preset will once again be selected. Keep in mind that presets are specific to your version of QGroundControl. If you share a Plan file with a preset with another user, incorrect behavior may occur if that other user also has a preset of the same name but different settings.

en/PlanView/PlanGeoFence.md

@@ -15,7 +15,7 @@ To create a GeoFence:
 1. Select the *Geofence* radio button above the Mission Command List
 
    ![Select geofence radio button](../../assets/plan/geofence/geofence_select.jpg)
-1. Insert a circular or polygon region by pressing the **Circular Fence** or **Polygon Fence** buttons, respectively.
+1. Insert a circular or polygon region by pressing the **Circular Fence** or **Polygon Fence** button, respectively.
    A new region will be added to the map and to the associated list of fences below the buttons.
 
   > **Tip** You can create multiple regions by pressing the buttons multiple times, allowing complex geofence definitions to be created.
@@ -24,7 +24,7 @@ To create a GeoFence:
 
      ![Circular Geofence](../../assets/plan/geofence/geofence_circular.jpg)
      - Move the region by dragging the central dot on the map
-     - Resize the circle by dragging the map dot on the edge of the circle (or you can change the radius value in the fence panel).
+     - Resize the circle by dragging the dot on the edge of the circle (or you can change the radius value in the fence panel).
    - Polygon region:
 
      ![Polygon Geofence](../../assets/plan/geofence/geofence_polygon.jpg)
@@ -38,7 +38,7 @@ To create a GeoFence:
 You can select a geofence region to edit by selecting its *Edit* radio button in the GeoFence panel.
 You can then edit the region on the map as described in the previous section.
 
-Regions can be deleted by pressing the associated **Del** button
+Regions can be deleted by pressing the associated **Del** button.
 
 
 ## Upload a GeoFence

en/PlanView/PlanView.md

@@ -42,7 +42,7 @@ The following sections explain some of the details in the view.
 
 ## Planned Home Position {#planned_home}
 
-The *Planned Home* shown in *Plan View* is used to set the approximate start point when planning a mission (i.e. when a vehicle may not even be connected to a vehicle). 
+The *Planned Home* shown in *Plan View* is used to set the approximate start point when planning a mission (i.e. when a vehicle may not even be connected to QGC). 
 It is used by QGC to estimate mission times and to draw waypoint lines.
 
 ![Planned Home Position](../../assets/plan/mission/mission_settings_planned_home.jpg)
@@ -52,7 +52,7 @@ The altitude for the planned home position is set in the [Mission Settings](#mis
 
 <img src="../../assets/plan/mission/mission_settings_planned_home_position_section.jpg" style="width: 200px;"/>
 
-> **Tip** The Fly View displays the *actual* home position set by the vehicle firmware when it arms (this where the vehicle will return in Return/RTL mode). 
+> **Tip** The Fly View displays the *actual* home position set by the vehicle firmware when it arms (this is where the vehicle will return in Return/RTL mode). 
 
 
 ## Plan Tools {#plan_tools}
@@ -152,7 +152,7 @@ This allows you to view the waypoint trajectory for your vehicle from takeoff to
   It has no actual impact on flying the mission. 
   The actual home position of a vehicle is set by the vehicle itself when arming.
 
-The section allows you to set the **Altitude** and **Set Home to Map Centre** 
+This section allows you to set the **Altitude** and **Set Home to Map Centre** 
 (you can move it to another position by dragging it on the map).
 
 

en/PlanView/pattern_fixed_wing_landing.md

@@ -14,15 +14,15 @@ Both the loiter and land points can be dragged to new positions, and a number of
 ## Creating a Landing Pattern
 
 To create a landing pattern:
-1. Open [PlanView](../PlanView/PlanView.md) *Plan Tools*).
+1. Open [PlanView](../PlanView/PlanView.md) *Plan Tools*.
 1. Choose the *Pattern Tool* from the *Plan Tools* and then select *Fixed Wing Landing Pattern*.
 
    ![Fixed Wing Landing Pattern](../../assets/plan/pattern/fixed_wing_landing_pattern_menu.jpg)
 
    This will add a *Landing Pattern* item to the mission list (on the right).
 
    ![Fixed Wing Landing Pattern](../../assets/plan/pattern/fixed_wing_landing_pattern_mission_item_initial.jpg)
-1. Click on the map to create both the loiter and landing points.
+1. Click on the map to create both the loiter point and the landing point.
    These can be moved on the map.
 
 Additional settings are covered in the next section.
@@ -56,8 +56,8 @@ The configurable options are:
 - **Heading** - Heading from loiter point to land point.
 - **Altitude** - Altitude for landing point (nominally zero).
 - *Radio Buttons*
-  - **Landing Dist** - Distance between loiter and landing points.
-  - **Glide Slope** - Glide slope between loiter and landing points.
+  - **Landing Dist** - Distance between loiter point and landing point.
+  - **Glide Slope** - Glide slope between loiter point and landing point.
 - **Altitudes relative to home** - Check to set all altitudes in mission item to be relative to home (default is AMSL).
 
 
@@ -73,4 +73,4 @@ The vehicle flares to landing using a flight path generated by the firmware betw
 
 If those two locations violate the vehicle's flare constraints (e.g. descent angle is too steep) an error will be raised after you upload the invalid mission to the vehicle.
 
-> **Note** On PX4, violating the flare constraints sends an error message to the ground station at upload time, and the autopilot will refuse to start the mission (since it fails integrity checks).
+> **Note** On PX4, violating the flare constraints sends an error message to the ground station at upload time, and the autopilot will refuse to start the mission (since it fails integrity checks).