m-apps:locAR News Notes FAQ Menu

The Data Menu

The Data menu allows you to control the transmission of your (real or simulated) location to other locAR users in your team and/or to your base server for observation using a geographic viewer (such as Google Earth).

It also presents the User menu button which allows you to set up a personal 'unique id' for yourself. TIP: if you have just started up locAR for the first time go to the User menu now to read about getting your unique id (or 'UID') and then come back here.

Location Privacy

The issue of 'location privacy' is often (rightly) raised in association with the use of 'tracking' applications which allow the sharing of location information between multiple viewers.

There are two different ways in which locAR can share your location:-

  • Base transmission: in which your location data is broadcast in a form that can be seen on a geographic viewer (such as Google Earth) by anyone who knows your UID (more details below).

  • Team transmission: in which your location data is exchanged with the locAR apps on the phones of the current members of a team that you have joined.

    Both base and team transmission have their own location privacy implications which mean that, although you may sometimes wish to share your precise geographic location, you should generally restrict that information in various ways. Therefore, locAR incorporates the controls described below (and on the Team List and Node pages) to help you to protect your location privacy. These controls allow you to:-

  • switch location transmission on or off globally or to individual team members

  • limit the accuracy with which your location is transmitted

  • set limits on the time for which transmission of your location is performed

  • create 'private zones' from which transmission of your location is disabled

    These controls should be understood and applied at all times by each user.

    Base Tx Resolution

    This is an extremely important control!

    The 'Base Transmission Resolution' is selected by the Res-/Res+ buttons either side of a status message beginning with "Base:". These buttons enable or disable the transmission of your location from your phone to your base server and adjust its 'resolution' - that is, the minimum angular distance between adjacent location values. This is key to maintaining your privacy if you are concerned about whether or not others can actually find you rather than just knowing your general location.

    The Res- and Res+ buttons select the 'base transmission status' (shown in the box between the buttons) as follows:-

    Base: Location Tx DISABLED!

    This is the setting you should select unless you want your (more or less precise) location broadcast to anyone who knows your UID!

    If any of the following selections are in force your location is sent to your base server every few seconds. There it is used to update a 'KML' file which allows your position to be seen and followed using a geographic data viewer such as Google Earth.

    The internet address of your KML file includes your UID (see below). You can have several UIDs, each based on a user name up to 20 characters long (via the User menu). Therefore, your first form of privacy control when using base transmission is to use a longer, 'hard to guess' UID which is known only to your intended viewers.

    If your current UID is "myuid" then your position can be seen in Google Earth by opening a network link to


    This shows a yellow 'location pin' annotated with your UID and (as available) current heading, speed and height. A short text message can also be appended via the "send to base" option.

    You can even control which direction and pitch your location is observed from by rotating and pitching your phone! The image is rotated to match the direction your phone is pointing in (if known). With your phone flat you look down upon your location pin from nearly overhead ... hold your phone upright to look up toward the horizon. The viewing distance is automatically adjusted according to your transmission resolution and speed.

    At each position update the location pin is placed randomly within the 'resolution box' described below, Expect to see your pin 'hopping about' unless you have Base: Tx FULL RESOLUTION! selected. Note that it takes several seconds for each new update to get from your phone and back to your viewer ... so give it time.

    If you reset your base transmission to "Location Tx DISABLED!" your viewed location is reset to zero latitude and longitude (somewhere in the Gulf of Guinea!) to hide any previous location.

    If you currently have base transmission disabled you can enable it by pressing Res+ to select ...

    Base: Tx Degrees (~ 100km)

    This is the most restricted setting and sends out your location for public viewing placed (randomly) within a one degree box. For example, if your actual location is N52.4, W3.7 degrees then the transmitted latitude (North-South position) is anywhere from N52 to N53 degrees and the longitude (East-West position) is from W3 to W4 degrees.

    In distance terms your latitude is sent out within bounds of approximately 110 kilometres (one degree of latitude). The distance bounded by a longitude step decreases as you move away from the Equator (by the cosine of the latitude). For example, at 50 degrees latitude one degree of longitude is a little over 70 kilometres.

    Therefore, the 'one degree' resolution is useful if you only want others to know which general region you are in.

    Pressing Res+ again selects more precise location transmission (through the stages below). Res- selects less precise (lower resolution) transmission and eventually disables it.

    Base: Deci-degrees (~ 10km)

    Increases the resolution by decreasing the latitude and longitude bound steps by a factor of 10 to deci-degrees - representing N-S distance steps of around 10km. Useful if you just want others to know, for example, which city you are in.

    The base tx resolution is automatically restricted to this setting (if currently finer) on leaving 'sim' mode (when your actual location will now be displayed!) to prevent inadvertent disclosure of your true location.

    Base: Centi-degrees (~ 1km)

    Decreases the latitude and longitude bound steps to centi-degrees - representing distance steps of around 1km. Useful if you just want others to know which general district you are in.

    Base: Milli-degrees (~ 100m)

    This is the finest restricted setting and sends out your location randomly within a 1 milli-degree box (roughly 110m N-S). This resolution should be sufficient for someone you know to find you in a public area without giving away your exact location.

    Finally ...


    Selects transmission of your latitude and longitude at the full available resolution. If you have GPS enabled and a good signal this can potentially pin down your location to just a few metres - so you should use this setting with care.

    From version 3.1, selecting Tx FULL RESOLUTION also makes the server generate a track for your location that is visible to any nearby locAR user, regardless of team membership.

    Team Tx Resolution

    These controls repeat the base transmission control options above, but affect the transmission of your position to other members of your current team (if any). The privacy implications of each setting should be less severe as only users who know the team name and password can see this data. You can also enable and disable transmission of your location to each team member individually via the team list menu.

    Each time your position is sent to your team members it is placed randomly within the resolution area. Therefore, unless you have "Team: Tx FULL RESOLUTION!" selected, you will 'hop around' on their maps. For example, on the "Team: Centi-degrees (~ 1km)" setting you will appear to hop around within a roughly 1km square area.

    You should have "Team: Tx FULL RESOLUTION!" selected if you are in War-loc mode, as your team members need to see exactly where you are (to shoot at you!).

    Also, when you are simulating your position you might wish to send it out precisely once you have moved away from where you really are. On leaving 'sim' mode (when your actual location will now be displayed!) the team tx resolution is automatically restricted to centi-degrees(~1km) to prevent inadvertent disclosure of your true location.

    Note that the base and team resolution controls are interlocked to ensure that the base transmission resolution is never finer than the team resolution. This lets you stop ALL transmission of your location to both team and public by repeatedly pressing the Team Res- button.

    Base Timer

    The Base Timer selects a time period (from 1 minute to 24 hours) after which the Base Tx Resolution is automatically reset to Base: Location Tx DISABLED!. Each press toggles successively longer periods of time, eventually returning to 'untimed'. Note that manual changes to the Base Tx Resolution always cancel any Base Timer.

    Team Timer

    The Team Timer does the same as the Base Timer for the Team Tx Resolution selection. When the Team Timer activates both the Team and Base Tx options are reset to ... Tx DISABLED due to the interlock, thereby turning off ALL location transmission.

    Clr (Clear)

    This button shows several additional controls which reset various locAR features.

  • Users clears the history of users.

  • Teams clears the history of teams that you have joined.

  • Otxts clears the history of your own texts (those that you have entered).

  • Tlist clears the list of texts that you have sent or received.

  • Nodes deletes all user nodes. You shouldn't need to do this often (as you can delete user nodes individually), but can be useful if you need to quickly clear out lots of user nodes.

  • Base clears (and re-establishes) the current connection to your base server.

  • Trail clears the history of trail points that you have visited.
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