01 – Indoors vs outdoors

Demystifying indoor positioning #

Indoor positioning is just like a GPS, but for the indoors. Just as the GPS leverages in the signals of a group of satellites orbiting around the Earth, Situm indoor positioning uses the signals present in today’s buildings, such as magnetic fields, Bluetooth from BLE beacons and WiFi from Access Points, to be able to pinpoint the user location with the maximum accuracy. But, contrary to the GPS, Situm does not need to know where the BLE beacons or WiFi APs are: we just need to know their signal maps across the environment.

In order to configure Situm in a building, an operator will have to upload the building floorplans to Situm Dashboard. After that, they will need to perform the calibration process with our app Situm Mapping Tool, which involves gathering the BLE and WiFi signals all across the environment to build their signal maps. From these calibrations, our AI algorithms create the signal maps that will be used to provide indoor & outdoor geolocation.

Situm only needs 3 things: a large building, its map, and an Android phone to calibrate its WiFi & BLE signals.

Once the signal maps are available, Situm’s algorithm will compare the signals received with those expected from the signal maps, and fuse this information with the user movement as estimated by the smartphone’s inertial sensors (compass, gyroscope and accelerometer) to provide a high accuracy without the need of additional hardware.

Based on this accurate geolocation, you will be able to locate your users, guide them, show them geolocated promotions, monitor their movement and gather insights within your buildings. And of course, when the user is outdoors, the GPS information is also available. Situm fuses this sensor as well, providing a seamless indoor & outdoor transition and allowing you to build indoor & outdoor geolocation apps with the same platform.

Building calibration: the secret sauce #

Calibration (or fingerprinting) consists on recording the WiFi / BLE signals that Situm needs to operate in a building. This process is central to Situm since it is absolutely required in order to get Situm up & running in your building: Situm will only work in areas that have been calibrated and, conversely, will not work in those that have not been.

Luckily, Situm Mapping Tool makes the calibration process an easy trip. Anybody can download this Android application and, just by walking around the building and pinpointing where they are every few meters in the app screen, gather all the WiFi & BLE signals to build the signal maps. After this, Situm will be ready to provide the indoor geolocation of every user.

Indoors vs outdoors #

Situm is an universal geolocation engine. This means that it works both in indoor and outdoor spaces, anywhere in the world, always providing the best possible position. More specifically, Situm is able to provide different levels of geolocation granularity.

Positioning typeEnvironment typeHow does it work?Location features
Indoor PositioningCalibrated venuesSitum computes the smartphone geolocation using information from its inertial sensors, WiFi, BLE, etc. 
If the venue has indoor and outdoor areas, Situm is able to fuse GPS information as well.
Situm provides the:
1. An absolute position (latitude-longitude in EPSG3857:WSG84).
2. A relative position associated with the environment: building identifier, floor identifier, X-Y coordinates (in meters from the bottom-left corner of the floor’s floorplan).
3. The orientation of the device around its 3 axis: bearing, pitch and roll.
Outdoor PositioningUncalibrated environments, anywhere in the world.Situm provides location information based on the one given by the device’s location provider, be it GPS, Apple Location, Google, etc.Situm only provides an absolute position in EPSG3857:WSG84 (latitude, longitude).

The following figure illustrates this concept, where the floorplan of the building is delimited by the dotted perimeter. We have calibrated the green area, and left the red area uncalibrated. In this environment, Situm will produce Indoor Positioning within the green area and Outdoor Positioning within the red area and beyond.  

a) Indoor

b) Outdoor

Building detection: Global vs Building mode #

Situm is not only able to provide your indoor or outdoor geolocation anywhere: it is also able to detect automatically the building where you are. To understand how this works, let’s examine first the two geolocation modes that Situm provides:

  1. Building Mode: computes the geolocation of an user but only if a building has been explicitly selected beforehand. This position will always be Indoor.
  2. Global Mode: is able to detect (automatically) the building where the user is and provide Indoor positioning within that building. Positioning can also be Outdoors if the user is not in any known building.

The following table describes their main differences:

FeatureBuilding ModeGlobal Mode
Automatic Building DetectionNo, one building must be selected manually.Yes
Automatic Transition between BuildingsNo, the user must manually select the building to which they’re transitioning to.Yes
Indoor PositioningYesYes
Outdoor PositioningNoYes
Recommended if…You only have one building or you are in a testing/development environmentMost cases
Comparison between Building and Global mode.

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