Quick Start
Before you do anything else, you should probably install some layers appropriate for
your location. To do this, touch the 
button at the bottom right of the screen, choose the Layers tab, and touch "Available
Layers". For each layer that you want to install, touch the blue arrow and then touch
"Install" on the next screen.
If you're on a mountain...
If you're lucky enough to be trying out the app from a location with a good view, enable Augmented Reality mode by turning on the compass, GPS and camera using the three buttons at the bottom left of the screen. (It may take a couple of seconds for the camera to come on after you touch the button.) This will show draw the computed skyline and show markers from the installed layers superimposed on the camera view.
You can capture the current view by touching the camera button. It is then possible to zoom in and out and pan around, and you can fine-tune the alignment of the skyline with the image. You can then save the view in the app's favourites, or you can export it to your phone's photo album.
If you're not on a mountain...
If you're in a flat city the augmented reality mode is unlikely to be very impressive.
Instead, touch the button and choose
the Favourites tab. From here you can select one the app's pre-loaded interesting views:
Alternatively, choose the Search tab and search for an interesting viewpoint in the installed layers:
If you have the app Topo Maps installed, then you can navigate to a point in that app and use its Go To Panoramascope feature to launch this app with the view from the selected location.
You can then zoom and pan around the view. It might take a few seconds before the view starts to appear as the app has to download the necessary terrain data before it can start. A spinner at the bottom right of the screen indicates when this is happening.
The following sections describe the app's features in more detail.
The Main Screen
The main screen shows the computed skyline and any enabled markers, optionally superimposed on the live view from the camera. Depending on the current settings, you may be able to pan and zoom around the screen using the usual gestures, i.e. using one finger to pan and two in a pinch/unpinch gesture to zoom in and out.
You can rotate the device to landscape orientation; the buttons will be shown at the side of the screen.
Buttons
The buttons at the bottom of the screen are, from left to right:
Enables and disables the compass. When the compass is enabled the
skyline will automatically move as you rotate the phone. When it's disabled, the skyline moves when you
touch the screen and drag it around. In both modes you can zoom in and out using two-fingered pinch and
unpinch gestures, unless 'live view' mode is enabled.
Enables and disables the GPS. When enabled, each time a GPS fix is
received a green light in the button flashes and the view is re-centred on the new location.
Enables and disables the camera. Note that there can be a delay
of a couple of seconds between touching the button and the camera image appearing.
Locks and unlocks the
horizon. When the horizon is locked you can only pan and zoom the view; when it's unlocked you can also
rotate it using two fingers. This button is not shown when the compass is active.
Determines whether the skyline and image or only the skyline move when you touch the
screen. This button is shown only when an image has been captured.
Captures the current image. This button is only
shown in 'live view' mode.
Shows the help screen.
Shows the settings screens, described
next.
The Settings Screens
If you touch the button at the bottom right of
the main screen, the app will "flip over" to show its settings screens. There are five of these, each
accessible by touching one of the tab buttons at the bottom of the screen:
Layers
Layers provide the data that's used to display place markers on the main screen and also the search screen, described below. Initially the app doesn't contain any layers; you need to install them first. To do this, first ensure that you have an internet connection and then touch "Available Layers" at the top of the Layers screen. A list of the layers currently available to install will be shown, grouped into approximate geographic areas:
Note that the geographic areas are just rectangles, so several parts of the world are mis-categorised:
To install a layer, touch the blue arrow to the right of the layer name and then touch the Install button on the next page:
When you return to the Layers screen, the installed layers will be listed. To the left of each name a coloured symbol shows what colour that layer's markers will use on the main screen, and to the right a switch allows each layer to be turned on and off:
Above the list of layers, a slider allows the size of the markers to be adjusted. The appropriate setting will depend on the sort of view: when distant mountains are visible large markers will be appropriate, while in urban environments then should be much smaller. The size shown in the slider is the height of the stem of the marker in metres.
Most of the layer data comes from the OpenStreetMap project, and is distributed on Creative Commons CC-BY-SA terms. The exception is the US Peaks data, which comes from the US Geological Survey and is in the public domain. There is also one "Wikipedia Features" layer for each region; this includes all features with Wikipedia pages where those pages include co-ordinates.
Search
Search uses the layer data described above, so you must first install appropriate layers and enable them on the Layers screen.
You can then type in a name and the screen will list matching place and features:
Touch a name and the main screen will show the view from that location.
Favourites
You can save your favourite views on this screen, which comes pre-loaded with some interesting views for you to try.
Before adding a view you might want to use the Settings screen, described below, to change the name of the viewpoint to something appropriate. Then, touching the + button at the bottom left of the Favourites screen will add the view to the top of the list.
You can erase and re-order favourites by touching the Edit button at the bottom right of the screen. To delete an item, touch the - button to its left. To re-order items, drag them using the stripe buttons to their right. When you've finished editing, touch the Done button at the bottom right of the screen.
Recent Locations
This screen records a new entry each time you change location (up to about 1,000 items) so that you can recall views from previous locations.
Settings
The Settings screen provides a number of miscellaneous features:
The Viewpoint section allows you to change the name of the current location, which is displayed at the bottom of the main screen and if the location is saved as a favourite, and to enter co-ordinates, and to adjust the viewpoint's height above the ground.
You can enter co-ordinates in latitude and longitude in various formats (the app will try to understand what you have entered and will suggest alternative formats if it cannot), or for locations in the UK you can enter an OS grid reference.
You can use the height above ground slider to get an aerial view from hundreds of metres up. Increasing it by a more modest amount is useful to exclude foreground obstructions from the view.
Two buttons provide functions related to photos. The first allows you to save the currently-visible view, including any photo, to your photo album. This is useful if you want to send the view by email or to transfer it to your computer. The second allows you to import a photo from your album, as if it had been taken by the camera.
The "Skyline Colour" slider allows you to adjust the colour used to draw the skyline, perhaps to provide a good contrast with the live view background.
A panel of up to six buttons lets you view a map centred on the current location using various web sites and map apps:
- You can use the built-in Google Maps app in map, satellite and hybrid mode.
- You can use the OpenStreetMap website.
- If you have the app 'Offmaps' installed, you can use that.
- If you have the app 'Topo Maps' installed, you can use that for the U.S. and Canada.
If you are running out of storage space on your phone, you have the option of deleting the previously-downloaded terrain data. Don't do this unnecessarily as it will make subsequent operation slower when the data is re-downloaded.
Normally the app downloads terrain data as necessary. If you expect to be without an internet connection, you can pre-load the required data in advance. To do this, navigate to the centre of the area of interest (e.g. using the Search screen, or by entering coordinates) and select the 'Pre-load terrain data' option. You will be asked to choose the approximate size of the area to download, and the app will start to fetch the data. You can continue to use the app while it does this, and it will show a message when it has finished.
The final options on the Settings page are an 'About' option that indicates which version of the app is running, and an option to view this web page.